DEPARTMENT OF EARTH SCIENCES
PART III PROJECT – 2016
TIME SCALE FOR CHOICE
Students are asked to complete and return the attached form indicating their provisional three
choices of project in order of priority by: Friday 5 February 2016
Students will appreciate that there is likely to be some sorting out in allocating topics.
SPECIFICATION
The specification for the Part III project is given on the Department website; Teaching section.
PROJECTS
Where projects involve a significant amount of field work, laboratory work, computer analysis,
literature review or Museum based work, this is indicated by the letters in brackets after the title.
1 Involving fieldwork and subsequent analysis (F)
2 Involving computer analysis (C)
3 Involving laboratory work and subsequent analysis (L)
4 Literature review (R)
5 Involving work in the Museum (M)
Students should discuss projects with the respective advisers BEFORE returning the choice
form.
FUNDING
It is regretted that there are no funds available from the University Vacation Studies Grant for the
Part III project. Some Colleges have special funds for which it may be possible to apply.
- For fieldwork projects, an indication is given by each title of the estimated costs of carrying out
the fieldwork. For several projects the adviser has funds available as indicated. Students will need
to raise their own funds for projects they devise.
- For project work carried out in Cambridge, i.e. for laboratory, computer and library projects and
for lab work associated with field projects, it is envisaged that a significant part of the work will be
undertaken in the Michaelmas Term. It may be possible to undertake some work in the Department
in the Long Vacation Term but students will have to negotiate with their College or provide funds
themselves to cover the cost of residence in College.
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Part III Projects 2016-17
OWN PROJECTS
Students are welcome to propose their own projects. The written proposal will require detailed
consideration by the Part III Project Committee to ensure its suitability. The proposal should be
about 500 words long, and explicitly address the following points:

The scientific objectives of the project. By contrast with the Part II project, it is not
sufficient simply to map an area. The project, whether field, lab or library-based, must
address a well-defined geological problem.

Logistic feasibility and safety. For laboratory projects, the necessary analytical and
technical facilities must be shown to be available. For field projects, exposure and safety
constraints must be shown not to impede the project.

The financial viability of the project. Funds for field work or facilities not available in the
Department will need to be raised by students.
The general guidance given in the Part II Project booklet on planning and executing field projects is
still applicable to Part III projects.
Morag Hunter
Teaching Administrator
January 2016
2
Part III Projects 2016-17
PART III PROJECT – 2016
Please PRINT very clearly!
Name ...................................................................................................
College ................................................................................................
E-mail address ...................................................................................
Provisional project choice; please give project number, title and name of adviser. Please do not
choose more than one project offered by any supervisor.
1. ...............................................................................................
2. ...............................................................................................
3. ...............................................................................................
If you wish to propose a project please attach a specification.
Please return this form
by Friday 5 February 2016
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Part III Projects 2016-17
PART III PROJECTS 2016
1
Quantifying susceptibility of biocomposites to dissolution in reduced pH (L)
Liz Harper & Professor Lloyd Peck (British Antarctic Survey)
2
Ammonite palaeobiology: growth rate and longevity (L)
Liz Harper
3
Convolute lamination in Welsh upper Silurian rocks: record of earthquakes, storms or
tsunamis? (F)
Nigel Woodcock
4
Transition from a Carboniferous delta to turbidite fan: Culm Basin, North Devon (F)
Nigel Woodcock, Neil Davies
5
Thermal evolution and viscous relaxation of icy satellites (C)
Francis Nimmo (University of California Santa Cruz) / David Al-Attar (Bullard)
6
Sensitivity of the Earth's free oscillations to lateral density variations in the mantle (C)
David Al-Attar
7
Alum mining in the Kharga basin, Egyptian Sahara (L)
Judith Bunbury
8
What controls earthquake stress drops? (C)
Alex Copley
9
Earthquake triggering by megathrust events (C)
Alex Copley and Camilla Penney
10
Do solid Earth and ocean tides affect the occurrence times of earthquakes? (C)
Alex Copley
11
The contact aureole of the Younger Giant Dyke, SW Greenland (L)
Marian Holness and Chris Richardson
12
How fast does convergent evolution run? (LR/C)
Simon Conway Morris and Jen Hoyal Cuthill
13
Induced Seismicity Caused by Stress Changes from Bardarbunga Caldera
Collapse in Iceland during 2014-15 eruption (C/F)
Rob Green, Bob White
14
Deposition from waxing and waning pyroclastic flows (L)
Lotty Gladstone & Andy Woods, BP Institute
15
Post-Eruptive Dyke Seismicity Following the 2014-15 Bárðabunga-Holuhraun
Intrusion and Fissure Eruption, Iceland (C/F)
Jenny Woods, Bob White
16
Nervous system and affinities of the Burgess Shale worm Amiskwia sagittiformis (L)
Javier Ortega-Hernández and Nicholas Butterfield
17
What in Earth is happening at 1000km? Searching for deep seismic observations (C)
Jennifer Jenkins, Sanne Cottaar
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Part III Projects 2016-17
18
Mapping meso-scale structure(s) above the core-mantle boundary
(deep Earth seismology) (C)
Sanne Cottaar
19
Mantle convection viewed through the filter of gravity and topography (C)
John Rudge
20
Phosphatized fossils and "coprolites" in the Cambridge Greensand (L)
Nick Butterfield
21
Fossil phantom midges: palaeobiology of an exceptionally preserved insect biota (L)
Nick Butterfield
22
Phosphatic scale-microfossils from the middle Neoproterozoic of NW Canada (L)
Nick Butterfield
23
Pyritization of shelly fossils (L)
Nick Butterfield and Sasha Turchyn
24
Microbially driven geochemical heterogeneity in the Norfolk Salt Marshes: deep biosphere and
the carbon cycle (F/L)
Sasha Turchyn
25
Modelling of geochemical reactions in a flow through reactor- can we reconstruct the
influence of climate change events on subsurface geochemistry? (C)
Sasha Turchyn
26
The behavior of calcium isotopes during clay precipiation in Marine Sediments (L)
Sasha Turchyn
27
Investigating a suspected microbial role in the formation of iron-rich laminae in an
early (Carboniferous) lake ecosystem (L/F)
Neil Davies, Sasha Turchyn
28
Marine or non-marine? The problem of Cambro-Ordovician sheet sandstones (F/L)
Neil Davies and Sasha Turchyn
29
The onset, spread and recovery from Kasimovian rainforest collapse: visualizing the
Pangean “coal gap” (R)
Neil Davies
30
Sedimentology and/or palaeobiology of early terrestrial ecosystems in Scotland (F)
Javier Ortega-Hernández and Neil Davies
31
The earliest river bends? Anatomy of an exceptionally preserved meandering channel
complex in the Welsh Old Red Sandstone (F)
Neil Davies, Will McMahon
32
Evolution and extinction recorded in alluvial ichnofacies during the climax of
Pangean assembly (R)
Neil Davies
33
The Earth’s exhaust pipe: carbon outgassing in arcs (R)
Marie Edmonds and Sasha Turchyn
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Part III Projects 2016-17
34
Defining the first Heinrich events in the North Atlantic
David Hodell and Alex Piotrowski
35
Understanding the role of ice-sheets in millennial climate variability in the early Pleistocene
David Hodell & Alex Piotrowski
36
Three-dimensional reconstruction of sedimentation on the SW Iberian margin during
the last glacial cycle
David Hodell, Luke Skinner, Simon Crowhurst, Nick McCave
37
Modern sediment and isotopic properties on the Portuguese margin in relation to
Atlantic Ocean hydrography.
David Hodell, Nick McCave, Luke Skinner
38
The Cause of Colour Variations in Iberian Margin Sediment Cores
David Hodell, Luke Skinner, Sasha Turchyn, Simon Crowhurst
39
Trace element and isotope geochemistry of gypsum: constraining the marine vs.
nonmarine debate (L)
Sambuddha Misra, Aleksey Sadekov, and David Hodell
40
Micro-raman studies of barite at high pressure and high temperature conditions
Sébastien Facq and Simon Redfern ([email protected])
41
Using principal component analysis of x-ray diffraction data to quantify mineral mixtures
Giulio Lampronti and Simon Redfern ([email protected])
42
Structure/property relationships of mollusc shells as natural biocomposite materials (L)
Liz Harper and Michael Carpenter
43
Eocene predator-prey interactions : a comparison between the high and mid latitudes
Liz Harper & Alistair Crame (British Antarctic Survey)
44
Timescales of magma storage and transport in the Krafla volcanic system
John Maclennan, Euan Mutch
45
Further constraints on mantle temperatures from olivine-spinel thermometry
John Maclennan, Simon Matthews, Oli Shorttle, Marie Edmonds
46
Non traditional stable isotope fractionation between silicate melts and minerals (F,L)
Ed Tipper, Marian Holness
47
Himalayan chemical weathering and carbon transfer triggered by the April 2015
Nepal Earthquake (L, F)
Ed Tipper, Mike Bickle
48
Climate dependency of Li isotope fractionation during weathering (L)
Ed Tipper, Alex Piotrowski, Ruth Hindshaw
49
Deep crustal processing of primary melts beneath Continental Flood Basalts Provinces
Sally Gibson
50
Controls on the sulfur isotopic composition of the mantle (L)
Marie Edmonds, Sasha Turchyn and Sally Gibson
51
Crystal cargoes of Kilauean eruptions (L)
Marie Edmonds and John Maclennan
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Part III Projects 2016-17
52
Gas pipes associated with magmatic intrusions (F)
Marie Edmonds and John Maclennan
53
Chlorine cycling through subduction zones (R)
Marie Edmonds and Helen Williams
54
Testing sulfur isotopes and sulfur concentrations as indicators of marine influence in
Palaeozoic and Precambrian sedimentary rocks (L)
Sasha Turchyn and Neil Davies
55
Chemical weathering fluxes and processes in the Mekong River (L, F)
Ed Tipper, Mike Bickle
56
Investigating ice-sheet collapse at the penultimate deglaciation: dissecting
‘Heinrich event 11’ (L)
Luke Skinner
57
The Southern Ocean and atmospheric CO2: constraining ‘solubility pump’
changes during the last glacial period (L)
Luke Skinner and Sambuddha Misra
58
Developing proxies for deep ocean oxygenation: a powerful metric of past marine
carbon cycling
Luke Skinner, Sambuddha Misra, David Hodell
59
The Atlantic Ocean in overdrive: did abrupt changes in ocean ventilation
drive centennial atmospheric CO2 jumps over the last 42,000 years? (L)
Luke Skinner
60
Reconstructing glacial Indian summer monsoon variability at sub-annual to
sub-decadal scale in a stalagmite from NE India using LA-ICPMS
Sebastian Breitenbach, Aleksey Sadekov and Luke Skinner
61
Evaluating environmental changes in (sub-)tropical stalagmites at annual to
sub-decadal scale using tandem 14C and U-series dating methods
Sebastian Breitenbach, Aleksey Sadekov and Luke Skinner
62
The morphology of impact craters (L)
Jerome Neufeld (BPI, Earth Sciences, DAMTP), Stuart Dalziel (DAMTP)
63
Fingered spreading of the Icelandic plume (L)
Jerome Neufeld (BPI, Earth Sciences, DAMTP)
64
An assessment of early diagenetic influences on the chemistry of infaunal versus epifaunal
benthic foraminifera. (L)
Mervyn Greaves, Aleksey Sadekov, David Hodell.
65
Archosaurian tracks from the Connecticut Valley: characterising a previously
unknown collection of tracks at the Sedgwick Museum (L/M)
David Norman
66
Micro-CT scanning of a fish skull (preserved in the round) to investigate
its detailed internal anatomy, function and systematic position (L/M)
David Norman
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Part III Projects 2016-17
67
Micro CT scanning of an intact skull of the Neogene crocodile (“Crocodilus
hantonensis”) in order to investigate the details of its internal anatomy, function and
relationships. (L/M)
David Norman
68
Interacting single-domain clusters: a good analogue of the pseudo-single domain (PSD) state?
(L and C)
Richard Harrison, Nono Lascu, Josh Einsle
69
Magnetism of ocean sediments: quantitative unmixing of magnetic signals during Heinrich
events (L and C)
Richard Harrison, Nono Lascu, Dave Hodell
70
Dynamics of Magma Degassing (L)
Andy Woods and Marie Edmonds
71
Magmatic plumbing under Skaftafell, Iceland
John Maclennan, Simon Matthews, Oli Shorttle
72
Investigating ocean circulation patterns during early rifting of Pangea: a multi-disciplinary
approach.
Morag Hunter, Liz Harper and Alex Piotrowski
73
Boron Isotope and B/Ca Study of Marine Carbonates During Over Glacial – Inter Glacial
Climate Transitions
Sambuddha Misra, Mervyn Greaves and Harry Elderfield
74
Boron Isotopes of Marine Carbonates During Paleocene – Eocene Thermal Maxima (PETM)
Sambuddha Misra, Mervyn Greaves and Harry Elderfield
8
Part III Projects 2016-17
1
Topic:
Quantifying susceptibility of biocomposites to dissolution in reduced pH (L)
Supervisors:
Liz Harper & Professor Lloyd Peck (British Antarctic Survey)
Introduction
At times of decreased sea water pH (both now and in the past) the greatest challenge to marine organisms
with carbonate skeletons is to maintain them against dissolution. The idea that ‘calcite is good and aragonite
is bad’ is far too simplistic. This project will investigate the susceptibility of a wide range of molluscan
biocomposites to realistic levels of dissolution and to relate this to composite characteristics. These data are
interesting in relation to current and past ocean acidification but also in understanding adaptations for
undersaturated habitats (e.g. freshwater or the deep sea) and to the study of taphonomy.
Aims
(1) To measure dissolution rates for a range of different molluscan biocomposites at control (ambient) and
experimental (predicted end-Century) pH levels, (2) to characterize the biocomposites, for example, in terms
of carbonate mineralogy, crystal size and organic content. (3) to make a detailed survey of dissolution
surfaces to determine exact nature of the damage and (4) to perform a comparative analysis of any
differences between biocomposites in their susceptibility to dissolution.
Methods
Polished tiles of fresh molluscan shell material will be deployed in the ocean acidification mesocosm and
control at Plymouth Marine Laboratory for a period of at least 100 days. Shell loss will be quantified by
accurate weight loss and the dissolutional surfaces studied by scanning electron microscopy (SEM). At least
8 different biocomposites will be studied, including a range of aragonite and calcite, markedly different
organic contents and microfabrics. These will be characterized using a range of techniques including SEM,
XRD and thermogravimetric analysis. Data will be analysed providing experience in a range of statistical
tests and techniques.
Logistics and resources
It will be essential that the student can spend one or two weeks after the Part II exams to prepare the samples
and deploy them in the mesocosm. A range of facilities available within the department (including optical
and scanning electron microscopy, use of the Palaeontology Lab for preparation, computers and the library)
are required. Use of the Plymouth mesocosm is already agreed.
Reading
Hall-Spencer JM, Rodolfo-Metalpa R, Martin S, Ransome E, Fine M, Turner SM, Rowley
SJ,Tedesco D, Buia M-C (2008) Volcanic carbon dioxide vents reveal ecosystem effects of ocean
acidification. Nature 454: 96-99.
Harper, E.M. (2000) Are calcitic layers an effective adaptation against shell dissolution in the
Bivalvia? Journal of Zoology, 251: 179-186.
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Part III Projects 2016-17
2
Topic:
Ammonite palaeobiology: growth rate and longevity (L)
Supervisor:
Liz Harper
Introduction
There are many aspects of ammonoid palaeoebiology that are unknown. While some questions might be
forever unanswered, others are more tractable. How fast did they grow? When did they grow? How
long did individuals live? When did a juvenile become adult? Questions like these are relatively easily
answered for molluscs where shell preservation is good, but not for ammonites with their thin aragonitic
shells. However, the often overlooked calcitic aptychi offer a good chance to collect interesting data and
establish a protocol for further studies.
Aims
To collect sclerochronology data based on both morphometrics and stable isotopes derived from calcitic
aptychi of different taxa from different facies and time slices. These data may also provide useful
insight into life habits.
Methods
The student will aim to collect their own material from the Jurassic locally, a
s well as using previously collected material from the Sedgwick Museum and in the Supervisor’s
collection. The project has four main tasks: (i) to establish a method for studying growth lines within
aptychi; (ii) to undertake microstructural studies in order to assess the extent of diagenetic alteration
which may have occurred, (ii) to collect oxygen and carbon isotope analyses in order to establish
whether lines are annual or not and also give palaeoenvironmental information; and (iv) to collect and
compare growth rate and longevity data.
Logistics
The necessary sectioning, optical and scanning electron microscope facilities are available in the
Department of Earth Sciences. Stable isotope determinations will be conducted by the student at the
Godwin Laboratories. A limited number of thin sections will also be required, and cutting facilities will
be required in order to make acetate peels of aptychi. The material collected will ultimately be
deposited in the Sedgwick Museum.
Reading
Jones, D. S. and Quitmeyer, I.R. (1996). Marking time with bivalve shells: oxygen isotopes
and season of annual increment formation. Palaios 11: 340-346.
Landman et al (2013). A New Approach for the Determination of Ammonite and Nautilid Habitats.
PLoS One 9 e87479.
Schöne, B. R., Fiebig J; Pfeiffer M; et al. (2005). Climate records from a bivalved Methuselah
(Arctica islandica: Mollusca; Iceland). Palaeogeography, Palaeoclimatology, Palaeoecology
228: 130-148
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Part III Projects 2016-17
3
Topic:
Convolute lamination in Welsh upper Silurian rocks: record of earthquakes, storms or
tsunamis? (F)
Supervisor:
Nigel Woodcock
Aims
Convolute lamination is a product of soft-sediment deformation within a partially liquefied sedimentary bed.
Renewed interest in this structure arises from its possible triggering either by earthquakes, by large storms,
or even by tsunamis. Can so-called seismites, tempestites and tsunamites be distinguished by whether their
convolute lamination shows a post-depositional or a syn-depositional geometry? This project will address
this question by detailing convolute lamination from the storm sands of the Bailey Hill Formation (Ludlow
Series, Silurian, eastern Mid-Wales). The convolute geometries will be compared with published examples
and with recently studied examples from the Aberystwyth Group turbidites of west Wales.
Methods
A substantial existing collection of samples of convolute lamination from the Bailey Hill Formation will
provide the main material for the study, but a field visit to the area will be needed to log sections and study
the geological context. In Cambridge, cut and polished faces will need to be prepared. Acetate peels may
prove a successful method for recording the structural detail from cut faces; other samples will need to be
scanned. Logged sections will be quantitatively analysed. A literature review of convolute lamination styles
from other areas will be undertaken and the Welsh material placed in a wider context, allowing general
conclusions to be reached.
Logistics
Up to a week’s fieldwork will be required during the summer vacation in the area between Knighton and
Llandrindod Wells, Powys. Access to a car would be an advantage. Sample preparation will require training
and supervision in sawing and grinding rocks. All necessary laboratory and library facilities are available in
Cambridge.
Reading
Allen, J. R. L. 1977. The possible mechanics of convolute lamination in graded sand beds. Journal of the
Geological Society, 134, 19 - 31.
Holland, C.H. 1959. On convolute bedding in the lower Ludlovian rocks of north-east
Radnorshire.Geological Magazine. 96, 230 - 236.
McClelland, H. L. O., Woodcock, N. H. & Gladstone, C. 2011. Eye and sheath folds in turbidite convolute
lamination: Aberystwyth Grits Group, Wales. Journal of Structural Geology, 33, 1140-1147.
Tyler, J. E. & Woodcock, N. H. 1987. Bailey Hill Formation: Ludlow Series turbidites in the Welsh
Borderland reinterpreted as distal storm deposits. Geological Journal 22, 73-86.
Resources
The student will need subsistence and travel costs of about £300, depending on field time. Some contribution
from the advisor’s research funds will be possible. There will be a call on rock preparation and thin-section
facilities, computers, microscopes and library.
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Part III Projects 2016-17
4
Topic:
Transition from a Carboniferous delta to turbidite fan: Culm Basin, North Devon (F)
Advisors:
Nigel Woodcock, Neil Davies
Aims
The Culm Basin is a flexural basin developed during the later stages of the Variscan Orogeny (late
Carboniferous) in southwest England. It started as a marine turbidite basin now preserved as the Crackington
Formation. Later the basin was probably a freshwater lake, with a turbidite fan on the lake floor (Bude
Formation) fed through a river-dominated delta (Bideford Formation) at its northern edge. The down-system
transition from delta to fan is well exposed, but in a folded and faulted section that requires more study. The
work will address sedimentological problems such as the links between delta and slope mudstones, between
mouth bar sands and thick-bedded fan turbidites, and between slumps on the slope and in the turbidite fan.
These are problems of topical interest in deep-water hydrocarbon exploration.
Methods
Field work in the area will traverse accessible sections between Westward Ho! and Hartland, north Devon.
Sections will be logged, contact relations documented, and structural and sedimentological data measured.
Facies will be photographed and described, and representative samples collected. Lab work will include
description of thin sections and polished slabs, analysis of directional data, and drafting of logs. Culm Basin
literature will be reviewed and integrated with new data to produce palaeogeographic and
chronostratigraphic views of the facies distribution and history.
Logistics
Up to two weeks’ summer fieldwork will be required in north Devon. Bus services are patchy and access to
a car would be helpful. Sample preparation will require training and supervision in preparing rocks. All
necessary laboratory and library facilities are available in Cambridge.
Reading
De Raaf, J. F. M., et al. (1965). Cyclic sedimentation in the lower Westphalian of north Devon.
Sedimentology 5: 1-52.
Edmonds, E. A., et al. (1979). Geology of Bideford and Lundy Island. London, Memoirs of the Geological
Survey of Great Britain, Sheet 292 with sheets 275, 276, 291 and part of sheet 308.
Prentice, J. E. (1960). The stratigraphy of the Upper Carboniferous rocks of the Bideford region, north
Devon. Quarterly Journal of the Geological Society 116: 397-405.
Burne, R. V. (1995). Return of 'The fan that never was': Westphalian turbidite systems in the Variscan Culm
Basin: Bude Formation (south-west England). Special Publications of the International Association of
Sedimentologists 22: 101-135.
Resources
The student will need subsistence and travel costs up to about £500, depending on field time. Some
contribution from the advisors’ research funds will be possible. There will be a call on rock preparation and
thin-section facilities, computers, microscopes and library.
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Part III Projects 2016-17
5
Title:
Thermal evolution and viscous relaxation of icy satellites (C)
Supervisor:
Francis Nimmo (University of California Santa Cruz) / David Al-Attar (Bullard)
Background and aims:
Many icy moons appear to have maintained significant long-term strength. Their shapes and gravity fields
are not what would be expected for a purely fluid body; in many cases they appear to retain "fossil bulges" in
a similar manner to the Earth's Moon. On the other hand, large impact basins on these satellites are
sometimes anomalously shallow, suggesting that the subsurface ice has undergone at least some flow. There
thus exist at least two observational constraints, at different length-scales, which must be satisfied by any
model of long-term thermal evolution. The aim of this project is to carry out simple conductive forward
models of icy moon thermal evolution to investigate which scenarios are consistent with the observational
constraints.
Methods:
The conductive thermal evolution code has already been written. For a particular model run, the depth to the
base of the elastic layer can then be calculated at any time. The degree of compensation associated with this
particular elastic thickness may then be derived (analytically) for comparison with the relaxation state of the
global shape and of large impact basins. Previous studies have shown that this elastic calculation provides an
acceptable approximation of the full viscoelastic problem. The most promising target for this approach is the
moon Rhea; time permitting, other targets include Mimas, Tethys and Dione.
Logistics/Finance:
A basic understanding of heat conduction, flexure and viscous relaxation is required; although the required
code is largely written, some knowledge of computer language is highly desirable. The student will spend ~2
months over the summer working in California with Prof. Nimmo; it is anticipated that the bulk of the
analysis will be completed over this period, with writing up taking place during the Cambridge academic
year under David Al-Attar’s supervision. Financial support for travel and lodging will be provided at a level
to be determined.
Reading:
Relaxation of long-wavelength topography and the thermal evolution of Rhea, S. Kamata, F. Nimmo,
46 LPSC, abstract. no. 1092, 2015.
Impact basin relaxation on Rhea and Iapetus and relation to past heat flow, O.L. White, P.M. Schenk,
A.J. Dombard, Icarus 223, 699-709, 2013.
Impact basin relaxation as a probe for the thermal history of Pluto, S. Kamata, F. Nimmo, J. Geophys.
Res. 119, doi:10.1002/2014JE004679, 2014.
th
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Part III Projects 2016-17
6
Topic: Sensitivity of the Earth's free oscillations to lateral density variations in the mantle (C)
Supervisor: David Al-Attar
Background
It is currently unclear if convection within the Earth's mantle is driven primarily by thermally induced
buoyancy, or whether lateral variations in composition also play an important role. Constraints on the
structure of the mantle are largely obtained through the analysis of seismic waves observed after
earthquakes. Most seismic observations such as travel times are sensitive to variations in wave speeds only,
and this information is not sufficient to differentiate between underlying thermal or compositional effects.
Observations of the Earth's free oscillations at long periods (greater than around 100 seconds) are, however,
directly sensitive to lateral variations in density, and accurate knowledge of such density variations would
play a central role in understanding the driving forces of mantle convection. Though a number of previous
studies of lateral density variations have been made, they were subject to rather severe computational
limitations which bring into question the validity of their results.
Aims
The aim of this project is to re-examine the sensitivity of free oscillations to lateral density variations using
recently developed computational techniques, and so gain a better understanding of what it may be possible
to learn about the Earth using such observations. The student will use existing programs to generate
synthetic free oscillation spectra in a large range of earth models, and try to assess the likelihood that the
effects of density on the spectra can be isolated and recovered. A particular question of interest is the extent
to which lateral density variations are significant relative to expected observational errors, and addressing
this problem will require the systematic examination of free oscillation data in an attempt to quantify their
observational errors.
Logistics
This project will suit a student with interest in the study of the deep Earth, computational methods, and data
analysis. Though the main programs for the project will be provided, it will be necessary for them to develop
some simple codes for plotting and analysis of results, and so a willingness to learn or apply some basic
programming (e.g. using Python) is necessary. An understanding of the details of the free oscillation
calculations is not expected nor required, but the project will provide scope to learn about some aspects of
computational seismology. There is no fieldwork associated with the project, and computational resources
will be provided.
Reading
Ishii M. & Tromp J., 1999. Normal-mode and free-air gravity constraints on lateral variations in
velocity and density of the Earth's mantle, Science, 285, 1231—1236.
Kuo C. & Romanowicz B., 2002. On the resolution of density anomalies in the Earth's mantle using
spectral fitting of normal mode data. Geophys. J. Int., 150, 162—179.
Al-Attar D., Woodhouse J.H., & Deuss A., 2012. Calculation of normal mode spectra in laterally
heterogeneous earth models using an iterative direct solution method. Geophys. J. Int., 189, 1038
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Part III Projects 2016-17
7
Topic:
Alum mining in the Kharga basin, Egyptian Sahara (L)
Supervisor:
Judith Bunbury
Lab based project - samples already available from Kharga Oasis
The Kharga depression is an area of over 3000 km2 in the Eastern Sahara (Egypt). The area was famous in
Roman times for its wine production and remains an agriculturally rich one. Roman ruins in the area are
associated with large areas of mining including strip mining, shoad mining and prospection. These mining
settlements are located around the abandoned town of Um el-Debadib, the micro-oasis of Ain Lebakh and
the Persian temple of Hibis. However, little is known about the nature of the deposits extracted, the method
of purification or the infrastructure of the mines in antiquity although they were described by Beadnell
(1909) as alum mines.
The North Kharga Oasis Survey (NKOS) has already compiled field notes and collected some samples of
evaporites, shales and rhizocretions from the area. These data augmented by GoogleEarth images, ASTER
DEM and other freely available data will be used to explore the extent and scope of the mines and identify
the targets for exploration and extraction. As field systems and wells are also visible on satellite imagery
and are known from field observations, the mine infrastructure (food, water and transport) can also be
evaluated.
The project will require analysis of samples, including bulk analysis and leaching of soluble material for
analysis by, for example, XRD/XRF to determine the target of mining. It will also require modelling of the
extent of ancient lakes to determine whether supergene enrichment of alum has lead to the production of
economic deposits. Engagement with the mineralogical, mining and archaeological literature will be
required.
Beadnell, H. G. L.. 1909. “Kharga Oasis”. Review of An Egyptian Oasis. The Geographical Journal 34 (5).
[Wiley, Royal Geographical Society (with the Institute of British Geographers)]: 561–62.
doi:10.2307/1777291.
Fred Wendorf and The Members of the Combined Prehistoric Expedition. 1977. Late Pleistocene and
Recent Climatic Changes in the Egyptian Sahara. The Geographical Journal, Vol. 143, No. 2 (Jul., 1977), pp.
211-234Published by: Wiley on behalf of The Royal Geographical Society (with the Institute of British
Geographers) Stable URL: http://www.jstor.org/
Kröpelin, S., Verschuren, D., Lézine, A.-M., Eggermont, H. , Cocquyt, C., Francus, P., Cazet, J-P., Fagot,
M., Rumes, B., Russell, J.M., Darius, F., Conley, D.J., Schuster, M., von Suchodoletz, H., and Engstrom,
D.R., 2008. Climate-Driven Ecosystem Succession in the Sahara: The Past 6000 Years. Science 320, 765.
Kuper, R and Kröpelin, S, 2006. Climate-controlled Holocene Occupation in the Sahara: Motor of Africa’s
Evolution. Science 313, 803-7.
15
Part III Projects 2016-17
8
Topic:
What controls earthquake stress drops? (C)
Supervisor:
Alex Copley
A close examination of the stress drops in earthquakes has revealed that they vary between events (as was
mentioned in the part 2 geophysics course). This variation is important, as it provides a key that will allow us
to understand the material properties of fault planes, which is a hotly-debated and important topic (e.g. from
the perspective of understanding earthquake hazard). Possible causes of the stress drop variations include
differences in fault friction, fault depth extent, slip rate, or total displacement (“structural maturity”).
Unfortunately, there are insufficient well-constrained models for the distribution of slip in earthquakes to
allow us to understand the variations in stress drop based solely upon this source of data. However, there are
increasingly large numbers of recent, historical, and pre-historic earthquake ruptures that have been
documented in the field, which will allow new insights to be gained into this subject. By analysing the
displacement-to-length ratios of these ruptures, it will be possible to obtain an estimate for the stress-drops in
these events, and therefore create a new global database of the lateral variations in earthquake stress drops.
This database of fault ruptures will be based upon an existing one compiled by Manighetti et al (2007), but
will also be expanded to include significant numbers of other events. The new database will then be
examined from the perspective of understanding the properties and behaviour of active faults, by addressing
the following interesting questions:
(1) Do the variations of earthquake stress drops show a correlation with fault slip rate, depth extent, total
displacement, local lithology, or other quantities? In short, what factors govern fault stress? Do the patterns
pointed out by Scholz et al 1986 (inter- vs. intra-plate differences) still hold true, in the presence of modern
compilations of data and our improved knowledge of fault slip rates and depth extents? Manighetti et al
(2007) explained some of the variation as being due to the differences between single- and multi-segment
ruptures. However, observations of significant variation of stress-drop between known single-segment
ruptures imply this is not the only governing factor (if a factor at all).
(2) What is the average displacement-length ratio in earthquakes, by how much does it vary, and is it
predictable based upon knowledge of the location and geometry of faulting? How do we estimate the likely
amount of slip in future earthquakes from observations of the along-strike lengths of faults (e.g. for the
purposes of earthquake hazard assessment)?
This project will fist involve compiling observations of earthquake rupture lengths and displacements from
published papers. Most of the time will be spent analysing the resulting database, and interpreting the results
from the perspective of fault rheology and dynamics.
References
Manighetti et al, Earthquake scaling, fault segmentation, and structural maturity, Earth and Planetary
Science Letters, v 253, p 429-438,2007.
Scholz et al, Scaling differences between large interplate and intraplate earthquakes, Bulletin of the
Seismological Society of America, v 76, p 65-70, 1986
16
Part III Projects 2016-17
9
Topic:
Earthquake triggering by megathrust events (C)
Supervisors:
Alex Copley and Camilla Penney
Large (e.g. magnitude 7+) earthquakes on subduction zone megathrusts sometimes trigger similarly-large
normal faulting earthquakes in the adjacent oceanic outer-rise (i.e. in the downgoing plate) in the subsequent
months to years (e.g. Ammon et al 2008). The timing of these triggered events is thought to be due to the
stress changes caused by the rupture on the subduction megathrust. However, an important observation is
that not all megathrust events trigger outer-rise normal faults (e.g. Craig et al 2014). Similar effects are
known from the continents, at the large thrusts on the margins of mountain ranges (e.g. where India underthrusts Tibet).
At present, there is no understanding of the factors that control whether a thrust event is likely to trigger
these large normal-faulting earthquakes, which have been recorded with magnitudes up to 8.1 (e.g. offshore
the Kuril Islands in 2007; Ammon et al 2008). However, we would like to understand this phenomenon,
because of the obvious hazard implications. Large normal-faulting earthquakes in oceanic outer rises can
produce significant Tsunamis, and many people live in the continental forelands underlain by such normal
faults.
This project will address this topic by combining two types of work. First, some simple conceptual models
will be constructed to examine the stresses imposed on the under-thrusting plate by the earthquake cycle on
the adjacent megathrust, and by the bending of the plate. By examining the interplay between the main
parameters that control the behaviour (e.g. the stress-drop on the megathrust, the repeat time of the
earthquakes, and the elastic thickness of the under-thrusting plate) it will be possible to establish the
dominant controls on whether or not triggering occurs. Second, the results of the models will be compared to
observations from oceanic subduction zones and continental megathrusts, and this comparison will allow the
material properties of the lithosphere to be estimated – a topic of great current debate.
References:
Ammon et al, A great earthquake doublet and seismic stress transfer cycle in the central Kuril islands,
Nature, v. 451, p. 561-565, 2008.
Craig, Copley, Jackson, A reassessment of outer-rise seismicity and its implications for the mechanics of
oceanic lithosphere, Geophysical Journal International, v. 197, p. 63-89, doi: 10.1093/gji/ggu013, 2014.
17
Part III Projects 2016-17
10
Title:
Do solid Earth and ocean tides affect the occurrence times of earthquakes? (C)
Supervisor:
Alex Copley
There has been a long history of vigorous argument about whether the timing of earthquakes is affected by
the stress changes due to solid Earth and ocean tides. This issue is important because whether or not these
tides can affect the timing of earthquakes gives us insights into the nature and timescale of the earthquake
nucleation process, which we currently know little about. The previous studies that have addressed this issue
have done so by making large assumptions about the geometry and slip-sense of the faults in the databases
examined, which is likely to explain the large range of contradictory conclusions previously put forward
(e.g. Vidale et al 1998, Tanaka et al 2002, Cochran et al 2004). This project will, for the first time, take a
large catalogue of moderate and large earthquakes (e.g. Mw 6 to 9) with well-determined fault geometries
and slip senses, and ask whether there is any signal of tidal triggering present. The results will then be used
to place constraints on the physical processes that occur when earthquake slip nucleates.
The project will involve running existing computer programs that calculate the solid Earth tides due to the
gravitational effects of the Sun and Moon, and also the deformation of the solid Earth that results from
loading by ocean tides. The variation in stress through time at the locations of the earthquakes will then be
calculated, and estimates will be made of whether the tidal stresses were enhancing or reducing the driving
stresses on the fault planes at the times of the earthquakes. These calculations for the catalogue of
earthquakes with well-determined geometries and slip senses will allow a statistical assessment of whether
tides are important in controlling earthquake occurrence times, and therefore produce conclusions regarding
the mechanism and timescale of earthquake nucleation.
References
Cochran et al, Earth Tides Can Trigger Shallow Thrust Fault Earthquakes, Science, v.306, p. 1164-1166,
2004.
Tanaka et al, Evidence for tidal triggering of earthquakes as revealed from statistical analysis of global data,
Journal of Geophysical Research, v107, doi:10.1029/2001JB001577, 2002.
Vidale et al, Absence of earthquake correlation with Earth tides: An indication of high preseismic fault
stress rate, Journal of Geophysical Research, v103, p. 24,567-24,572, 1998.
18
Part III Projects 2016-17
11
Topic:
The contact aureole of the Younger Giant Dyke, SW Greenland (L)
Supervisors:
Marian Holness and Chris Richardson
Aims
The Younger Giant Dyke (YGD) is part of the Proterozoic Gardar Complex of SW Greenland. It extends for
more than 100 km along strike and reaches almost 1 km in width. It intruded into crustal rocks of broadly
granitic composition. Although published studies state that no melting occurred in the contact aureole,
preliminary observations demonstrate that melting did indeed occur, forming localized pockets of
granophyre. The project involves the detailed examination of the aureole to determine the extent of melting
and recrystallization in order to constrain the temperature profile and hence to place some constraints on the
fluid dynamical behavior of the dyke (did it act as a conduit or was it emplaced as a single injection? Did it
convect or was it a static body of magma?).
Methods
Imaging of polished thin sections using cathodoluminescence can be used to determine the extent of subsolidus recrystallization and grain growth in quartz, and to identify those rocks containing very low (<1
vol%) partial melt. Electron probe analysis will be used to measure Ti contents in quartz to determine the
temperature of this recrystallization and melting.
The samples have already been collected, so this project is lab-based. It will involve considerable
petrographic observation, together with the collection and interpretation of microprobe data. The thermal
profile will be interpreted using simple diffusion models, in collaboration with Dr. Chris Richardson (BPI).
Finance
There are no costs involved in the project, as the analytical costs will be shared by the department and a
NERC grant.
Reading list
Bufe, N.A., Holness, M.B. and Humphreys, M.C.S. 2014 Contact metamorphism of Precambrian gneiss by
the Skaergaard Intrusion. Journal of Petrology, 55: 1595-1617.
Upton, B.J.G., Parsons, I., Emeleus, C.H., & Hodson, M.E. (1996) Layered alkaline igneous rocks of the
Gardar Province, South Greenland. In: (ed. Cawthorn, R.G) Developments in Petrology, 15: 331-364.
19
Part III Projects 2016-17
12
Topic:
How fast does convergent evolution run? (LR/C)
Supervisors:
Simon Conway Morris and Jen Hoyal Cuthill
Aims
Convergent evolution, whereby the same “solution” is reinvented, is very common. Classic examples include the
evolution of the camera-eye or gliding. In many cases the number of instances of convergent evolution is relatively
limited, even if the consequences are momentous. In other cases, however, the number of examples of convergence in a
given clade (of whatever size) is very large, sometimes exceeding a hundred. The project has two principal aims: within
the phylogeny of the clade what are the timings of these convergences? Broadly do they show a left skewed, right
skewed or normal distribution? Does this deviate from our expectations if convergence is randomly distributed?
Second, even in a clade with recurrent convergences, there are frequently “hot-spots” where the frequency of
convergences appears to be far above random. Is this statistically correct?
Methods
The starting point will be to assemble a number of examples of highly recurrent convergence. Likely examples include:
C4 and CAM photosynthesis, myremechory (ant dispersed seeds), parasitic (and hemi-parasitic) plants, thermogenesis,
aquatic plants, pollination syndromes and bioluminescence.
In each case the approach will be first to obtain the best possible molecular phylogeny of the clade from literature
sources (this may be cross-phylum). This may require some reanalysis of genetic data, and the possibility of timecalibration should be considered. Then the aim will be to measure all branch lengths, including that proportion that
have a convergent end-point. In at least some cases it may also be necessary to sub-divide the clade into smaller units
and investigate relative timings of a convergence on a more local scale. There is a potential for some computer
programming to conduct simulations for comparison against the real data. In either case similarities and dis-similarities
in the rates of evolution that lead to a convergent outcome (versus unique traits) will indicate whether or not a deeper
evolutionary pattern exists. In addition, the relative frequency of convergences across the clade will be calculated in
order to see if there is any sort of clustering. If these distributions are recurrent in otherwise unrelated groups, then this
will then invite an investigation of what might be controlling the rates of convergent evolution. Finally, and if time
permits, where possible the known genetics/molecular mechanisms will be compared in order to see whether at a more
fundamental level basic similarities of process (and by implication pre-disposition exist) in a way consistent with
concepts of deep homology.
Logistics
The project will be dependent on literature searches and computation.
A large data-base on convergent evolution is available, but the student will need to prepare their own phylogenetic data
bases.
Necessary training in accessing examples of convergent evolution (SCM) and computational methods (JHC) will be
given. Because of the very large data sets, collection of data should begin in the summer.
Finance
Will require access to dedicated computer.
Reading List
Buchman, S.L. (1983) Buzz pollination in angiosperms. In Handbook of Experimental Pollination Biology (eds C.E.
Jones & R.J. Little), pp. 73-113. Van Nostrand Reinhold.
Chase, M.W. et al. (2009) Murderous plants: Victorian gothic, Darwin and modern insights into vegetable carnivory.
Botanical J. Linn. Soc. 161, 329-356.
Conway Morris, S. (2015) The Runes of Evolution. Templeton.
Cook, C.D.K. (1990) Aquatic plant book. SPB Academic.
Friedman, J. & Barrett, S.C.H. (2008) A phylogenetic analysis of the evolution of wind pollination in angiosperms. Int.
J. Plant Sci. 169, 49-58.
Grass Phylogeny Working Group II (2012) New grass phylogeny resolves deep evolutionary relationship and discovers
C4 origins. New Phytologist 193, 304-312.
Haddock, H.D. et al. (2010) Bioluminiscence in the sea. Annual Rev. Marine Sci. 2, 443-493.
Lengyel, S. et al. (2009) Ants sow the seeds of global diversification in flowering plants. PLoS ONE 4, e5480.
Lüttge, U. (2004) Ecophysiology of crassulacean acid metabolism (CAM). Ann. Botany 93, 629-652.
Medvedeva, S.E. et al. (2005) BIOLUMBASE: The database of natural and transgenic bioluminescent organisms.
Luminesence 20, 90-96.
Osborne, C.P. et al. (2014) A global database of C4 photosynthesis in grasses. New Phytologist 204, 441-446.
Sage, R.F. et al. (2011) The C4 plant lineages of planet Earth. J. Exp. Botany 62, 3155-3169.
Seymour, R.S. & Schultze-Motel, P. (1997) Heat-producing flowers. Endeavour 21, 125-129.
20
Part III Projects 2016-17
13
Topic:
Induced Seismicity Caused by Stress Changes from Bardarbunga Caldera
Collapse in Iceland during 2014-15 eruption (C/F)
Supervisors:
Rob Green, Bob White
Aims
In August 2014 the caldera of the large Bárðabunga volcano under the Vatnajökull ice cap in Iceland started
subsiding as melt flowed 48 km underground along a dyke at 7 km depth. It started erupting two weeks later
forming the Holuhraun lava field, which is the biggest Icelandic eruption for over 230 years.. As melt flowed
out from Bárðabunga, the caldera collapsed. The changes of stress caused by the dyke inflation and
propagation, and by the caldera subsidence have triggered induced seismicity in the surrounding area to
distances of more than 30 km. The Coulomb stress changes across fault planes can be modelled and
compared to the orientation of fault planes deduced from fault plane solutions of the induced earthquakes.
The rate of decrease of seismicity can be used to constrain rate-state parameters.
Methods
An array of 75 Guralp 3-component broadband seismometers deployed by Cambridge University is currently
operating in central Iceland. The student may if they wish participate in fieldwork during summer 2016 to
service and deploy seismometers and to download data the instruments have recorded remotely during the
past year. The student will use the Bullard computing facilities to process seismic data and to locate
earthquakes. Fault plane solutions and moment tensor solutions will also be calculated for the clearer
events, and other techniques such as joint event relocation after cross-correlation of seismic waveforms will
be applied. This project requires a student who is at home with computing and numerical processing and will
require commitment to learning new computing software and the Linux operating system.
Logistics
The student will be able to visit Iceland to assist in fieldwork in summer 2016 if they wish, though this is not
essential for the project. Other graduate students engaged in research on similar seismological projects will
provide support in the computer programs needed to manage the data collected. The student will have an
office at the Bullard Labs and will use computers there to process and analyse the raw seismic data, and then
to start picking travel times, locating the earthquakes and deriving fault plane solutions.
Reading
Green R.G., T. Greenfield, and R.S. White (2015), Triggered earthquake suppressed by an evolving stress
shadow from a propagating dike. Nature Geosci. 8, 629-632, doi:10.1038/ngeo2491.
Sigmundsson, F. et al. (2015) Segmented lateral dyke growth in a rifting event at Bárðarbunga volcanic
system, Iceland, Nature, 517, 191‒195, doi:10.1038/nature14111
Tarasewicz, J., White, R. S., Brandsdóttir, B. (2014). Seismogenic magma intrusion before the 2010 eruption
of Eyjafjallajökull volcano, Iceland, Geophysical Journal International, 198, 906‒921, plus supplementary
information, doi: 10.1093/gji/ggu169
www.cam.ac.uk/research/discussion/luck-and-lava
Resources
All costs of participating in the fieldwork in the Icelandic interior (c 2 weeks) will be provided from Bob
White’s research funds: the student will need to fund their own airfare to/from Iceland (cheap flights are
available). Previous students have often stayed on for a vacation before or after the fieldwork. The project
will use computing and office facilities at Bullard Labs. Useful web site of Icelandic Holuhraun eruption –
http://en.vedur.is/earthquakes-and-volcanism/articles/nr/2947
21
Part III Projects 2016-17
14
Topic:
Supervisors:
Deposition from waxing and waning pyroclastic flows (L)
Lotty Gladstone & Andy Woods, BP Institute
Many theoretical and experimental studies of pyroclastic flows and turbidity currents have focussed on two
end-member source conditions: either a sudden release of sediment or a steady input. Neither of these source
conditions is particularly relevant to the natural environment: there is evidence that volcanic eruptions can
increase in intensity over time and then decrease. The role of this time-dependent intensity has been
investigated for eruption columns but not on the behaviour and subsequent deposit features of associated
pyroclastic density currents. Similarly, there has been little research looking at the different depositional
signatures that may be left by waxing and waning turbidity currents flows in the deep ocean. The aim of the
project is to create reproducible laboratory-scale flows where the source changes systematically with time
and identify some key features of flow and the deposits. The latter may then be tied to field observations in
the literature on both turbidites and ignimbrites.
Methods and logistics
This research is primarily experimental with some supporting theoretical analysis. The student will create
turbulent flows in one of the long flume tanks at the BPI Flow Labs, Bullard Site. Observations on the
behaviour of the flow can be made through analysis of high-speed images, and the resulting deposit
(thickness and streamwise grading) can be measured.
Resources
The flume tank and associated kit forms part of the core BPI equipment. Analysis of samples will be
undertaken using the Coulter Counter (Sed Lab, Downing Site). Analysis of the flow will be via dye work
and image anlaysis. Full lab training will be given. Desk space and a PC can be provided, should you be
working at the BPI over the summer. Ideally a portion of the research will be carried out during the summer
vacation; funds are available to help with accommodation expenses.
Contact
Lotty ([email protected], 65705) or Andy ([email protected], 65702)
Amy, L.A. and Peakall, J. and Talling P.J. (2005) Density- and viscosity-stratified gravity currents: insight
from laboratory experiments and implications for submarine flow deposits. Sedimentary Geology, 179, 529.
Woods, A.W. and Bursik, M.I. (1994) A laboratory study of ash flows. J. Geophys. Res., 99, 4375-4394.
Nakajima, T. (2006) Hyperpycnites deposited 700 km away from river mouths in the central Japan Sea. J.
Sed. Res., 76, 60-73.
22
Part III Projects 2016-17
15
Topic:
Post-Eruptive Dyke Seismicity Following the 2014-15 Bárðabunga-Holuhraun
Intrusion and Fissure Eruption, Iceland (C/F)
Supervisors:
Jenny Woods, Bob White
Aims
During two weeks in August 2014 a dyke intruded 46 km laterally from subglacial, central volcano
Bardarbunga to the ice-free Holuhraun lava field, resulting in a 6-month fissure eruption. The eruption was
declared officially over in February 2015, but seismic activity continues in early 2016, steadily decreasing,
along the dyke length and at Bardarbunga. The source mechanisms for these earthquakes are to be
determined, arising perhaps from continued adjustment along pre-existing fault planes or magma fracture
during cooling and contraction. The post-eruptive failure mechanisms can be compared with those observed
during the propagation and eruption phases, and combined with analysis of seismicity rates and earthquake
magnitudes, to further understand the physical processes at play during and after dyke intrusion and
eruption.
Methods
An array of 75 Guralp 3-component broadband seismometers deployed by Cambridge University is currently
operating in central Iceland. The student may if they wish participate in fieldwork during summer 2016 to
service and deploy seismometers and to download data the instruments have recorded remotely during the
past year. The student will use the Bullard computing facilities to process seismic data and to locate
earthquakes. Fault plane solutions and moment tensor solutions will also be calculated for the clearer
events, and other techniques such as joint event relocation after cross-correlation of seismic waveforms will
be applied. This project requires a student who is at home with computing and numerical processing and will
require commitment to learning new computing software and the Linux operating system.
Logistics
The student will be able to visit Iceland to assist in fieldwork in summer 2016 if they wish, though this is not
essential for the project. Other graduate students engaged in research on similar seismological projects will
provide support in the computer programs needed to manage the data collected. The student will have an
office at the Bullard Labs and will use computers there to process and analyse the raw seismic data, and then
to start picking travel times, locating the earthquakes and deriving fault plane solutions.
Reading
Ágústsdóttir, T., Woods, et al. (2016). Strike-slip faulting during the 2014 Bárðarbunga-Holuhraun dike
Intrusion, central Iceland. Geophysical Research Letters, in press
Sigmundsson, F. et al. (2015) Segmented lateral dyke growth in a rifting event at Bárðarbunga volcanic
system, Iceland, Nature, 517, 191‒195, doi:10.1038/nature14111
White, R.S. et al. (2011). Dynamics of dyke intrusion in the mid-crust of Iceland, EPSL, 304, 300-312, doi:
10.1016/j.epsl.2011.02.038
www.cam.ac.uk/research/discussion/luck-and-lava
Resources
All costs of participating in the fieldwork in the Icelandic interior (c 2 weeks) will be provided from Bob
White’s research funds: the student will need to fund their own airfare to/from Iceland (cheap flights are
available). Previous students have often stayed on for a vacation before or after the fieldwork. The project
will use computing and office facilities at Bullard Labs. Useful web site of Icelandic Holuhraun eruption –
http://en.vedur.is/earthquakes-and-volcanism/articles/nr/2947
23
Part III Projects 2016-17
16
Topic.
Nervous system and affinities of the Burgess Shale worm Amiskwia sagittiformis (L)
Supervisors.
Javier Ortega-Hernández and Nicholas Butterfield
Aims
Amiskwia sagittiformis, Walcott 1911, is a vermiform soft-bodied animal endemic to the middle Cambrian
Burgess Shale in British Columbia. Despite being known for over one hundred years, the morphology and
phylogenetic affinities of Amiskwia have only been addressed in detail by a handful of workers. Although
initially regarded as a possible ancestor to chaetognaths (i.e. arrow worms), more recent work has suggested
that Amiskwia may be related to nemerteans (i.e. ribbon worms), or discarded all of these hypotheses.
Despite these complications, Amiskwia represents one of the few taxa from the Burgess Shale for which
putative nervous tissues have been identified, and thus offers a unique opportunity to explore the affinities of
these early problematic fossils from a neurological perspective. This project will use cutting-edge analytical
tools to scrutinize the overall morphology, neurological organization, and preservation of Amiskwia, and
integrate this information to illuminate the broader significance of this taxon.
Methods and logistics
The student will work with fossil material of Amiskwia currently on loan to JOH from the Smithsonian
Institution. The morphology and taphonomy of the fossils will be analysed with reflected and polarized light,
SEM, BSEM, and fluorescence microscopy. The student will be responsible for immersing himself/herself in
the relevant zoological literature, and to coordinate visits to appropriate museum collections (e.g. Natural
History Museum London) in order to study the anatomy of relevant extant organisms.
Finance
There are no major costs associated with this project. Analytical expenditures may be covered by active
grants.
Reading list
Butterfield, N. J. (1990). Organic preservation of non-mineralizing organisms and the taphonomy of the
Burgess Shale. Paleobiology, 272-286.
Conway-Morris, S. C. (1977). A redescription of the Middle Cambrian worm Amiskwia sagittiformis
Walcott from the Burgess Shale of British Columbia. Paläontologische Zeitschrift, 51, 271-287.
Edgecombe, G. D., Ma, X., & Strausfeld, N. J. (2015). Unlocking the early fossil record of the arthropod
central nervous system. Phil. Trans. R. Soc. B, 370, 20150038.
24
Part III Projects 2016-17
17
Title:
What in Earth is happening at 1000km? Searching for deep seismic observations (C)
Supervisors:
Jennifer Jenkins, Sanne Cottaar
Background
Something strange is happening at approximately 1000 km depth in the Earth’s mid-mantle. In some
locations subducting slabs are seen in tomographic models to stagnate at 1000 km depth (Fukao and
Obayashi, 2013), in others it appears mantle plumes are deflected at this depth (French and Romanowicz,
2015). While this depth range clearly plays a role in global mantle dynamics, there is no mantle mineral
phase transition predicted (as is the case around 410 and 660 km depth, Deuss et al. 2013). Hypotheses have
been put forward that this depth relates to a viscosity jump (Rudolph et al. 2015) or a density cross-over
(Ballmer et al. 2015).
Aims
We have recently worked on patchy seismic conversion signals coming from 1000km across Europe and the
North Atlantic. Finding converted signals means there is a relatively sharp impedance contrast and we have
hypothesised that these signals may be connected to a deflection of the Iceland plume eastwards beneath
Europe. We are looking for a student to extend this method to a stable geological region with a wealth of
data (e.g. Eastern North America or Australia) to test if such observations are only related to regions of
upwelling and downwelling. The student would use P to S seismic wave conversions from teleseismic
earthquakes (using the receiver function method, e.g. Jenkins et al. 2016). There is also the potential of using
underside bounces (SS precursors) as a complementary technique. The student will decide on a control
region and collect a seismic dataset from the IRIS online database. They will be provided with scripts to
create receiver functions which will then be combined using various stacking methods to look for a 1000km
signal.
Logistics
This project provides an excellent opportunity for students to directly contribute to an area of active research
within the deep earth community, helping to answer one of the current big questions. The project is likely to
suit a self-motivated, computer literate student or one who is willing to learn. The student learn to use
Linux, Python, Fortran and GMT (scripts will be provided). The student will be given a place to work at the
Bullard
Reading list:
·
Ballmer, Maxim D., et al. "Compositional mantle layering revealed by slab stagnation at~ 1000-km
depth." Science Advances 1.11 (2015): e1500815.
·
Rudolph, Maxwell L., Vedran Lekić, and Carolina Lithgow-Bertelloni. "Viscosity jump in Earth’s
mid-mantle." Science 350.6266 (2015): 1349-1352.
·
Jenkins, J., Cottaar, S., White, R. S., & Deuss, A. (2016). Depressed mantle discontinuities beneath
Iceland: Evidence of a garnet controlled 660 km discontinuity?. Earth and Planetary Science Letters, 433,
159-168.
·
French, S. W., & Romanowicz, B. (2015). Broad plumes rooted at the base of the Earth's mantle
beneath major hotspots. Nature, 525(7567), 95-99.
·
Deuss, Arwen, Jennifer Andrews, and Elizabeth Day. "Seismic observations of mantle discontinuities
and their mineralogical and dynamical interpretation." Physics and Chemistry of the Deep Earth (2013):
295-323.
25
Part III Projects 2016-17
18
Title:
Mapping meso-scale structure(s) above the core-mantle boundary
(deep Earth seismology) (C)
Supervisor:
Sanne Cottaar
Background
Over the past decades, deep earth scientists have found strong lateral heterogeneity in composition and
dynamics in the couple hundred kilometres right above the core-mantle boundary. There are two large
compositionally distinct piles of material, one under Africa and one under the Pacific. These 'piles' were first
seen in seismic tomographic models of shear wave velocity as being anomalously slow, and are therefore
generally called Large Low Shear Velocity Provinces (LLSVPs). While they can be seen in tomographic
models, higher resolution seismic modelling on a smaller scale has confirmed their sharp sides. In some
sense, the dichotomy of LLSVP and non-LLSVP regions above the core-mantle boundary is similar to the
ocean-continent dichotomy at the surface. Besides the two large anomalous LLSVPs, evidence for a smaller
separate anomaly beneath the Ural mountains in Russia has been found (Lekic et al. 2012). The existence of
smaller piles ('islands') puts further constraints on the dynamics and origin of these features.
Aims
Tomographic models suggest there is another meso-scale anomaly in the Southern Pacific. In this project,
you would hunt for suitable earthquake-station geometry (following Ford et al. 2006) to prove or disprove
that this anomaly is separated from the Pacific LLSVP. You will likely use a combination of different shear
phases (e.g. S, ScS, Sdiff, SKS). After downloading the data from the IRIS online database and processing
the data, you will be looking for travel-time, amplitude and waveform anomalies (using synthetic
seismograms as a reference) that can further constrain the geometry and wave-speed reduction of the
anomaly.
Logistics
This work could lead to new constraints on the composition and dynamics of the lowermost mantle, which
might lead to a publication. This is a computational project, and the student will learn to work with Linux
and Python. The student will be given a place to work at the Bullard.
Reading list

Lekic, V., Cottaar, S., Dziewonski, A., and Romanowicz, B., 2012, Cluster analysis of global lower
mantle tomography: a new class of structure and implications for chemical heterogeneity, Earth and
Planetary Science Letters, 357-358, 68-77

Ford, S.R., Garnero, E.J. and McNamara, A.K., 2006. A strong lateral shear velocity gradient and
anisotropy heterogeneity in the lowermost mantle beneath the southern Pacific. Journal of Geophysical
Research: Solid Earth (1978–2012), 111(B3). (This paper suggests useful geometries, although ten more
years of more dense coverage will be available now).
26
Part III Projects 2016-17
19
Topic:
Mantle convection viewed through the filter of gravity and topography (C)
Supervisor:
John Rudge
Aims
All the information we have on the planform of mantle convection comes from surface observations,
principally from gravity, topography, and seismology. However, these geophysical observations provide a
"filtered view" of the mantle circulation, and are sensitive to some parts of the mantle more than others. The
aim of this project is to produce a better understanding of the filtering process, in order to better interpret the
existing observations.
Methods
The student will run a series of numerical simulations of 3D thermal convection in a rectangular box using
the freely-available mantle convection code ASPECT. The results of these simulations will be post-processed
to calculate the surface observables, in particular gravity and topography. Parameters such as the Rayleigh
number, and the strength of the temperature-dependence of viscosity, will be varied to explore the changes in
convective planform that arise, and ultimately how these changes are recorded in the surface observables.
Logistics
This project is purely computational. The 3D convection simulations are computationally expensive, and
will be run on the University's high performance computing facility (Darwin). Post-processing will take
place on local machines at the Bullard laboratories.
The student will need to be comfortable coding and working with Linux. Most of the work will involve
running existing codes, e.g. running ASPECT with different parameter files. However, the student will be
expected to write small codes themselves for analysing the ASPECT output. Python codes already exist to
calculate gravity and topography from the ASPECT output, but may need minor modification by the student.
This project requires good mathematical skills. Familiarity with the mathematical language of linear filters
(e.g. Green's functions, convolution) is helpful, but not essential.
Finance
Time on the high performance computing facility will cost money, but this will be covered by the
supervisor's grant. There are no other costs associated with this project.
Reading list
Crosby, A.G., McKenzie, D., Sclater, J.G. (2006). The relationship between depth, age and
gravity in the oceans. Geophys. J. Int. 166, 553–573. doi:10.1111/j.1365-246X.2006.03015.x.
Parsons B. and Daly S. (1983). The relationship between surface topography, gravity anomalies, and
temperature structure of convection. J. Geophys. Res. 88, 1129-1144. doi:10.1029/JB088iB02p01129
aspect.dealii.org (ASPECT mantle convection code)
27
Part III Projects 2016-17
20
Topic:
Phosphatized fossils and "coprolites" in the Cambridge Greensand (L)
Supervisors:
Nick Butterfield
The Cambridge Greensand is renowned for its abundant phosphate nodules which occur both as fossil
steinkerns and “coprolites” (the basis of some of the first artificial fertilizers and a major
Cambridgeshire industry in the mid-19th century). This project will focus on reconstructing the
diagenetic history of these nodules through detailed petrographic study and consideration of the
conditions leading to their formation. The presence of extensive borings on and within the nodules also
indicates later stage reworking, with important palaeoecological implications. In broader terms, the
project will be investigating the biogeochemistry of the “Greensand Ocean” and the nature of marine
phosphogenesis. Local fieldwork will provide the material and general sedimentological context for
this study. Phosphatic nodules will be analysed both petrographically and geochemically.
Compton J et al. 2000. Variations in the global phosphorous cycle. SEPM Special Publication 66, 21–
33.
O’Connor B, Ford TD. 2001. The origins and development of the British Coprolite Industry. The
Bulletin of the Peak District Mines Historical Society 14, 46–57. (via Google)
28
Part III Projects 2016-17
21
Topic:
Fossil phantom midges: palaeobiology of an exceptionally preserved insect biota (L)
Supervisors:
Nick Butterfield
Laminated lake sediments commonly preserve a rich record of organic-walled fossils, mostly spores, pollen
and macroscopic plant material. Animal remains are less common and are usually limited to the isolated
sclerites of aquatic insects and crustaceans. There are, however, localized instances of exceptional
preservation where whole organisms are preserved in exquisite detail. The middle Miocene ‘Clarkia Beds’
of northern Idaho are famous for their extraordinary preservation of macroscopic leaves, but only recently
has the metazoan component been recognized. Among the most remarkable constituents are phantom midge
larvae (chaoborids), which occur in sufficient abundance to allow a complete anatomical reconstruction of
the original organism, including its ontogenetic development through several instars. Direct comparison
with modern chaoborid larvae will also allow broader aspects of the Clarkia ecosystem to be evaluated,
including water quality, temperature and levels of fish predation.
The fossils occur as thin carbonaceous films ranging from 100 microns to a centimetre in length. They will
be freed from the rock matrix via acid processing, collected from suspension using a pipette under a
binocular stereoscope, and studied using a combination of light and scanning electron microscopy. Analysis
of large populations will allow detailed reconstruction of particular taxa, as well as community structure and
whole-lake ecology.
Richter G, Baszio S. 2001. Traces of a limnic food web in the Eocene Lake Messel – a preliminary report
based on fish coprolite analyses. Palaeogeography, Palaeoclimatology, Palaeoecology 166, 345–368.
Smiley CJ, Gray J, Huggins LM. 1975. Preservation of Miocene fossils in unoxidized lake deposits, Clarkia,
Idaho. Journal of Paleontology 49, 833–844.
Uutala A. 1990. Chaoborus (Diptera: Chaoboridae) mandibles – paleolimnological indicators of the
historical status of fish populations in acid-sensitive lakes. Journal of Paleolimnology 4, 139-151.
29
Part III Projects 2016-17
22
Topic:
Phosphatic scale-microfossils from the middle Neoproterozoic of NW Canada (L)
Supervisors:
Nick Butterfield
Taxonomically problematic phosphatic scales in the ~720 Ma Fifteen Mile Group, Yukon Territory,
are the oldest known examples of biologically controlled mineralization in the fossil record.
Extractable from their host limestones via gentle acid processing, they exhibit extraordinary
micrometre- to nanometre-scale detail that can be used to resolve the subcellular mechanisms
responsible for their formation, with potential for identifying their phylogenetic affiliation
(somewhere among the protistan-grade eukaryotes). Broader investigation of this unique biota
could also shed important new light on the early evolution of intracellular biomineralization and
phosphate biogeochemistry in the run-up to the Cryogenian glaciations.
The student will carry out acid extractions and pick individual microfossils (< 50 µm) under a
binocular stereoscope. Most of the imaging will be done with SEM, though a range of
complementary techniques will also be investigated (e.g., FIB-SEM, EBSD, Raman, etc.)
Cohen PA, Schopf JW, Butterfield NJ, Kudryavtsev AB, Macdonald FA. 2011. Phosphate
biomineralization in mid-Neoproterozoic protists. Geology 39, 539–542.
Cohen PA, Knoll AH. 2012. Scale microfossils from the mid-Neoproterozoic Fifteenmile Group,
Yukon Territory. Journal of Paleontology 86, 775–800.
30
Part III Projects 2016-17
23
Topic:
Pyritization of shelly fossils (L)
Supervisors:
Nick Butterfield and Sasha Turchyn
Diagenetic replacement of shelly fossils with pyrite is a widespread phenomenon in the geological record,
but the processes by which it occurs are poorly understood. Unlike the replacement of non-mineralized
anatomy, pyritization of hard-tissue requires a precise correspondence between sulphide precipitation and
dissolution of the original carbonate/phosphate/silica phases. Palaeontological data reveal that some
biominerals and microstructures are conspicuously more susceptible to pyritization than others, though
the fidelity and degree of replacement is sensitive to local diagenetic conditions. The aim of this study is
to reconstruct the taphonomic pathways responsible for such fossils, and to consider their
palaeobiological implications.
The project will focus on a comparative analysis of pyritized fossils from the Middle Devonian Silica
Shale Formation (USA), and Upper Jurassic Kimmeridge Clay Formation (UK). Fossil material will be
examined using a combination of optical petrography, SEM and isotopic geochemistry. The data will be
used to derive a general model for substrate-specific pyritization, including the differential effects of
original mineralogy, microstructure, depositional environment and time.
The student will gain expert knowledge in aspects of sedimentary petrology, stable isotope mass
spectrometry, taphonomy and biomineralization. The project will include some field-work.
Raiswell R. 1997. A geochemical framework for the application of stable sulphur isotopes to fossil
pyritization. Journal of the Geological Society, London 154, 343–356,
Sommerfield CK, Aller RC, Nittrouer CA. 2001. Sedimentary carbon, sulfur, and iron relationships in
modern and ancient diagenetic environments of the Eel River Basin (U.S.A.). Journal of Sedimentary
Research 71, 335–345.
31
Part III Projects 2016-17
24
Topic:
Microbially driven geochemical heterogeneity in the Norfolk Salt Marshes: deep
biosphere and the carbon cycle (F/L)
Supervisor:
Sasha Turchyn
This project could be up to two students as there are several direction that it could go. There is the
possibility for it to be more laboratory versus more field work based as well.
Aims and Methods
In the absence of oxygen, microbial communities respire electron acceptors such as oxidized iron and
manganese, nitrate, and sulfate, using residual organic carbon as food. These microbial processes are
responsible for all organic carbon oxidation in the subsurface. A better understanding of how these
microbial communities interact, both among themselves and with the surrounding minerals and environment,
is essential for resolving redox processes in the deep biosphere and their link to the carbon cycle.
Geochemical measurements, including stable isotope ratios, provide a unique tool for exploring and
resolving these processes. The Norfolk Salt Marshes provide a natural laboratory for studying these
processes because of sharp redox gradients between the overlying oxygenated waters, supplied by daily
tides, and the supply of iron from below through the weathering of the underlying Carstone formation. The
net effect of these processes on the flux of carbon through the ecosystem remains ambiguous.
Logistics
This project would include field work in North Norfolk on the coast to collect samples from the water and
mud, including samples across tidal cycles and of coexisting channels and ponds to understand fluid flow
through the subsurface. Depending on the student’s interest the project could also involve using tracers to
track flow of water through the subsurface, or a laboratory component to culture and grow the microbes and
probe their behaviour. The rest of the project would be lab based and involve preparing the collected
samples for geochemical and isotope analysis. Having taking C3 and been to Norfolk on the Part II field trip
would be helpful.
Finance
The costs associated with the isotope and geochemical analyses will be covered by Sasha through existing
funding. The Student will need to come to Norfolk with others from the research group to do sampling
including possibly time series in the creeks and channels across tidal cycles. The student would need to
cover their own food, maximum £100-150 as the cost of the field work would be covered by existing
funding.
Reading list
DeBeer et al., Transport and mineralization rates in North Sea sandy intertidal sediments, Sylt-Rømø Basin,
Wadden Sea, Limnology and Oceanography, 50(1), 2005, 113–127
Bottcher et al., 1998 - Sulfate reduction related to the early diagenetic degradation of organic matter and
“black spot” formation in tidal sandflats of the German Wadden Sea (southern North Sea): stable isotope
(13C, 34S, 18O) and other geochemical results - Organic Geochemistry - Volume 29, Issues 5–7, November
1998, Pages 1517–1530
32
Part III Projects 2016-17
25
Topic:
Modelling of geochemical reactions in a flow through reactor- can we reconstruct the
influence of climate change events on subsurface geochemistry? (C)
Supervisors:
Sasha Turchyn
Introduction and Objectives
In carbon cycle investigations, comparatively little work has been done on the fate of carbon after burial.
Significant microbial activity exists in the subsurface, consuming dissolved inorganic carbon and recycling
that carbon back to seawater. How these microbes are impacted by changes in ocean water chemistry
through out the geologic record, however, is a critical question for quantifying past and future carbon cycle
variations.
To address this gap in knowledge, laboratory experiments are being conducted to simulate this subsurface
environment. A flow through reactor system, allowing for regular monitoring of both the porewater
chemistry and the microbial community, provides a framework for testing the influence of potential
variables. These include calcium versus magnesium ratios, dissolved inorganic carbon concentrations, and
nutrient levels among others. These results will form the calibrating data set for the proposed modeling
exercise, allowing us to extend the results and determine the influence of seawater chemistry change on the
sequestration of carbon in ocean sediment.
Methods
In this study, the student will build a model to represent and simulate recently collected data from a flow
through reactor system. The model will utilize microbial and geochemical reactions to reconstruct variables
such as sulfate reduction, iron reduction, anaerobic methane oxidation, alkalinity, saturation state, calcium
concentrations, and authigenic carbonate precipitation. Once calibrated, the model can be used to predict the
impact of variations in water chemistry and other parameters representative of different periods in the
geologic record.
Logistics
The student will gain a strong understanding of subsurface diagenetic processes and geochemical processes.
This project will be dominantly computationally based, with the possibility of participating in the laboratory
component if the student is interested. Basic programming skills (ideally Matlab) are highly desirable.
Reading
Meister, P. et al. 2013. Control of sulphate and methane distributions in marine sediments by organic matter
reactivity. Geochimica et Cosmochimica 104, 183–193
Schulz H. D. 2000. Quantification of Early Diagenesis: Dissolved Constituents in Marine Pore Water,
Springer, Berlin, pp 85-128.
Arning, E.T. et al. 2011 Organic carbon remineralisation and complex, early diagenetic solid–aqueous
solution–gas interactions: Case study ODP Leg 204, Site 1246 (Hydrate Ridge). Marine Chemistry, 126,
120-131.
Boudreau, B.P., 1997. Diagenetic Models and their Implementation: Modelling Transport and Reactions in
Aquatic Sediments. Springer, Berlin, New York.
33
Part III Projects 2016-17
26
Topic:
The behavior of calcium isotopes during clay precipiation in Marine Sediments (L)
Advisor:
Sasha Turchyn
Aims
Marine sediments are often studied to provide geochemical information about different processes that occur
below the seafloor. Calcium isotopes are used as a major tool in the study of marine sediments and the
associated porewaters due to the preferential uptake of the lighter 40Ca into the solid phase during
precipitation, as well the preferential adsorption of the lighter 40Ca onto clay minerals. Both of these
processes cause the remaining porewaters to be enriched in the heavier 44Ca. This study will be focusing on
IODP Site U1390, where there is 5-10% clay content (Kaolinite, Illite) as well as biogenic calcite and
calcareous muds. By studying the calcium isotopes of the porewaters and associated solid phases further
insight will be gained into the behavior of an important geochemical tool in marine geochemistry.
Logistics
The student will work with samples in the department or ordered from the Core repository in Bremen.
Geochemical preparation of many samples can be done before the student leaves for the summer, data
acquired over the summer so the student comes back to some data with which to build the project. There is
the possibility to expand this project to include numerical modeling of the pore fluids or examination of a
wider range of sediment cores and their geochemical chacteristics.
Reading
Teichert, B. M., Gussone, N., & Torres, M. E. (2009). Controls on calcium isotope fractionation in
sedimentary porewaters. Earth and Planetary Science Letters, 279(3), 373-382.
Ockert, C., Gussone, N., Kaufhold, S., & Teichert, B. M. A. (2013). Isotope fractionation during Ca
exchange on clay minerals in a marine environment. Geochimica et Cosmochimica Acta, 112, 374-388.
Resources
The costs associated with the isotope analyses will be covered by Sasha through existing funding.
34
Part III Projects 2016-17
27
Topic:
Investigating a suspected microbial role in the formation of iron-rich laminae in an
early (Carboniferous) lake ecosystem (L/F)
Advisors:
Neil Davies, Sasha Turchyn
Aims
Nonmarine habitats were steadily colonized by metazoans through the later half of the Palaeozoic, beginning
in the Ordovician. Of the freshwater habitats known today, the deep regions of permanent lakes were
colonized relatively late, with the first evidence for deep lacustrine ecosystems (from trace fossil
assemblages) appearing worldwide at the Mississippian-Pennsylvanian boundary (c. 323 Ma). The Bude
Formation, cropping out along the northern coast of Devon and Cornwall, provides one such record of
earliest Pennsylvanian age (c. 318 Ma). Associated with the early lacustrine metazoan trace fossils, a series
of unusual iron-rich laminae exist within the Bude Formation which potentially show evidence for recording
microbial mat communities within the early lake ecosystem. These laminae are characterised on their tops
by unusually small ripples which fall outside the normal range of hydrodynamic bedforms. Furthermore
they are associated with fish swimming trails that have left ‘levees’ in the sediment, indicating that the fish
were swimming through sludge. A variety of geochemical analytical techniques will be performed on
previously collected samples to try and understand the potential microbial role in the formation of these
features. This includes laser ablation or electronprobe work on the collected sediments to understand
changes in iron partitioning and availability, as well as trace isotope work.
Methods
Samples have already been collected of this material, so it could be a solely lab-based project. However, the
scope exists for a short fieldwork season to collect further samples and log the iron-rich horizons in situ.
Outcrops of the Bude Formation occur in easily accessible coastal outcrops around the town of Bude,
Cornwall.
Logistics
2-3 days of fieldwork in SW England would benefit the project (this could potentially be done at the same
time as the SW trip for which the 1B students are attending). Geochemical analysis of samples and collected
data will be completed in Cambridge in the Michaelmas term, although one week at the end of June is
beneficial for sample preparation.
Reading
1Buatois, L., Mángano, M.G., 2011, Ichnology: Organism-Substrate Interactions in Space and Time,
Cambridge University Press, 358 p. (sections 10.3 and 14.2.6).
2Higgs, R., 1991, The Bude Formation (Lower Westphalian), SW England: siliciclastic shelf sedimentation
in a large equatorial lake. Sedimentology, 38, 445-469.
3Davies, N.S., Liu, A.G., Gibling, M.R., Miller, R.F., 2016, Resolving MISS conceptions and
misconceptions: A geological approach to sedimentary surface textures generated by microbial and abiotic
processes. Earth-Science Reviews.
Resources
The student will need to apply for subsistence and travel costs for field work.
35
Part III Projects 2016-17
28
Topic:
Marine or non-marine? The problem of Cambro-Ordovician sheet sandstones (F/L)
Advisors:
Neil Davies and Sasha Turchyn
Aims
Prior to the evolution of land plants, rivers are thought to have behaved in a way analogous to certain glaciofluvial settings at the present day: rapidly prograding into the marine realm when flooding events permitted
the transport of a large amount of sediment, with marine reworking of these coastal deposits during
quiescent periods. This creates questions as to what constitutes ‘marine’ or ‘non-marine’ facies such that,
often lacking palaeontological or ichnological information, cross-bedded sheet sandstones of pre-Silurian
age can be problematic to decipher in terms of palaeoenvironment. A case in point are the CambroOrdovician red beds (Cap de Chevre Formation) of the Armorican Massif (cropping out in western Brittany,
France) which superficially appear to be monotonous sheets of cross-bedded sandstone. This project aims to
find out just how much sedimentological information can be gleaned from such successions in order to
provide insights into pre-vegetation river systems: with implications for studies ranging from determining
the timing of the onset of life on land to the interpretation of fluvial deposits on Mars. This will be coupled
with geochemical analysis on the sedimentary rocks, including but not limited to sulfur isotope analysis and
major element concentrations that are suggestive of terrestrial or marine deposition.
Methods
Outcrops of the Cambro-Ordovician Cap de Chevre Formation occur in patches along the Crozon peninsula.
The student will systematically log these sections to monitor changes in bed thickness and cross-bedding
style. This will be incorporated with petrographic, ichnological and geochemical data to attempt to find out
whether it is possible to determine marine influence in Cambrian sheet sands with any confidence.
Logistics
7-10 days of fieldwork in Brittany will be required during the summer vacation, partly supervised. The
supervisor will provide initial field supervision and training on observation and data collection. Analysis of
samples and collected data will be completed in Cambridge in the Michaelmas term.
Reading
1
Davies, N.S., Gibling, M.R., Rygel, M.C., 2011, Alluvial facies evolution during the Palaeozoic greening of
the continents: case studies, conceptual models and modern analogues. Sedimentology, 58, 220-258.
2
Went, D.J., 2013, Quartzite development in early Palaeozoic nearshore marine environments.
Sedimentology, 60, 1036-1058.
3
Suire, P., Dabard, M.P., Chauvel, J.J., 1991. Nouvelles données sur les séries rouges nord-armoricaines :
étude du bassin ordovicien de Bréhec. Comptes Rendus de l’Académie des Sciences, Paris, 312, II, 721-727.
(Available from advisor… in French with English abstract)
Resources
The student will need to apply for subsistence and travel costs for field work (total cost likely c. £400
depending on accommodation preferences). Access to a car would be essential – the outcrops are relatively
close to car ferry ports such as St. Malo. Some contribution from the supervisors’ research funds may be
possible.
36
Part III Projects 2016-17
29
Topic:
The onset, spread and recovery from Kasimovian rainforest collapse: visualizing the
Pangean “coal gap” (R)
Advisors:
Neil Davies
Aims
The concept of a global “coal gap” at the start of the Triassic has existed in the literature for a number of
years. The hypothesis states that the end-Permian mass extinction decimated global forests such that coal is
absent from the global rock record for at least the first few million years of the Triassic. However, the idea
is largely based on Australian and Russian coal-bearing sections. Whilst these do indeed persist until the
latest Permian and then disappear, in North American and European successions, the ‘last coal’ occurs in the
latest Carboniferous, associated with the Kasimovian event (in which global warming caused partitioning of
and collapse of equatorial rainforests). This project aims to see if the two are linked: was the end-Permian
extinction just the straw that broke the camel’s back? Can we map the spread of the ‘last coal’ in different
regions through Permian Pangea? Was the disappearance of coal a result of supercontinent-forced global
warming over 50 million years, rather than a specific event?
Methods
The project will be entirely based on a literature review that will be performed by the student. This review
will involve identifying global coal-bearing sedimentary successions of Carboniferous to Triassic age (And
their characteristics). The subsequent database arising from this review will place these occurrences in their
geographic and stratigraphic context relative to two of the biggest global environmental changes of the
latest Palaeozoic, ultimately permitting the plotting of coal forest distribution on time-stepped maps of
Pangea. Field data from Kasimovian and end-Permian coal successions is available to support the project.
Logistics
The project will be entirely library/office-based, and the student will be provided with all the literature thus
far assembled, and means to collect additional papers.
Reading
DiMichele, W.D., 2014, Dynamics of coal-age tropical vegetation. International Journal of Plant Sciences,
175.
Retallack et al., 1996, Global coal gap between Permian--Triassic extinction and Middle Triassic
recovery of peat-forming plants. Geol Soc America Bulletin, 108, 195-207.
Resources
No costs are envisaged, and the student will receive training from the advisor in the collection and
identification of pertinent data.
37
Part III Projects 2016-17
30
Topic.
Sedimentology and/or palaeobiology of early terrestrial ecosystems in Scotland (F)
Supervisors.
Javier Ortega-Hernández and Neil Davies
Aims
The Silurian (Wenlock) Cowie Formation in Stonehaven, Aberdeenshire, represents a fluvial environment
and has produced a rich fossil biota that comprises fish and arthropods; most notably, the latter include the
earliest evidence for air-breathing animals in the fossil record. Despite its significance for the origins of
terrestrialization, the Cowie Formation has not been systematically investigated, and most published work is
based on museum collections that lack detailed information regarding the sedimentological context. A recent
collection effort during 2015 produced a large quantity of well-preserved material, including unidentified
vertebrate fragments and large body fossils that may correspond to the oldest known land plants. This project
will investigate the depositional environment and fossil biota of the Cowie Formation, and explore the
implications of this locality for understanding the early terrestrialization of animals and plants.
Methods
The student will work with available fossil collections, housed at the Department of Earth Sciences, and will
also be involved in a short field season to Stonehaven to collect new material and study the depositional
environment. Fossil material will be classified, prepared, identified and correlated with the local
sedimentology; imaging and analysis will include SEM, BSEM, thin sections and light microscopy.
Depending on personal interest, the student may choose to put heavier emphasis on either the
sedimentological or palaeobiological components of this project, although some progress in both fronts is
expected. The workload could also be split into two different projects focussing on different aspects if both a
seds-minded and palaeo-minded student are interested.
Logistics
Fossil material collected in 2015 is immediately available for study at the Department of Earth Sciences, and
may be used for preliminary sedimentological analyses (e.g. thin sections). Fieldwork will take place in
summer 2016 (ideally before mid-July in order to be there with advisors, but timing is negotiable) and have a
minimum duration of seven days.
Finance
Fieldwork costs will be c. £200-500 depending on accommodation preferences. Students are encouraged to
seek funding from their College or other sources. Minor contribution to costs may be available from the
advisors’ funds.
Reading list
Blom, H. (2008). A new anaspid fish from the Middle Silurian Cowie Harbour fish bed of Stonehaven,
Scotland. Journal of Vertebrate Paleontology, 28, 594-600.
Wellman, C. (1993). A land plant microfossil assemblage of Mid Silurian age from the Stonehaven Group,
Scotland. Journal of Micropalaeontology, 12, 47-66.
Wilson, H. M., & Anderson, L. I. (2004). Morphology and taxonomy of Paleozoic millipedes (Diplopoda:
Chilognatha: Archipolypoda) from Scotland. Journal of Paleontology, 78, 169-184.
38
Part III Projects 2016-17
31
Topic:
The earliest river bends? Anatomy of an exceptionally preserved meandering channel
complex in the Welsh Old Red Sandstone (F)
Advisors:
Neil Davies, Will McMahon
Aims
As terrestrial vegetation evolved during the Palaeozoic, landscapes were significantly altered. River systems
evolved from broad, shallow systems with easily-erodible banks to meandering systems with stabilised
banks and muddy flood plains. This transition gave rise to a host of new architectural styles preserved in the
rock record. One of the earliest examples of this new, meandering form crops out in coastal exposures at
Llansteffan, Carmarthenshire. Utilising a variety of sedimentological and ichnological techniques, with a
particular emphasis on architectural analysis, this project aims to fully characterise the anatomy of this
particular river meander and reconstruct the hydrodynamics and palaeoecology of one of the oldest
meandering channel deposits in the geological record.
Methods
The student will spend a number of days making architectural panels, logging and collecting ichnological
and palaeocurrent data at the Llansteffan site (and possibly at other Welsh sites). The data collected will be
used to estimate questions surrounding the geomorphology and morphodynamics of the river systems
responsible for the deposition of the Welsh Old Red Sandstone, and compare these with other meander belts
preserved in the rock record.
Logistics
A week of fieldwork in south Wales would be necessary. Analysis of samples and collected data will be
completed in Cambridge in the Michaelmas term.
Reading
1
Marriott & Hiller, 2014, Fluvial style in the Lower Old Red Sandstone: examples from southwest Wales,
UK, Proceedings of the Geologists' Association, 125, 534–547
2
Davies, N.S., Gibling, M.R., 2010, Paleozoic Vegetation and the Siluro-Devonian Rise of Fluvial Lateral
Accretion Sets. Geology, v. 38, p. 51-54.
3
Ielpi & Ghinassi, 2014, Planform architecture, stratigraphic signature and morphodynamics of an exhumed
Jurassic meander plain (Scalby Formation, Yorkshire, UK). Sedimentology, 61, 1923-1960.
Resources
The student will need to apply for subsistence and travel costs for field work (c. £200-300).
39
Part III Projects 2016-17
32
Topic:
Evolution and extinction recorded in alluvial ichnofacies during the climax of
Pangean assembly (R)
Advisors:
Neil Davies
Aims
The late Carboniferous to Triassic periods saw most of the Earth’s continents assembled together in the
supercontinent Pangea. This huge continental expanse accounts for the prominence of non-marine strata of
this age in many regions of the world. Within these non-marine strata are a number of alluvial successions,
recording deposition by rivers that had previously seen progressive colonization by trace-making organisms
throughout the earlier Palaeozoic, particularly in the Carboniferous. The Permian-Triassic interval is also
noted for a number of extinction events, most notable amongst which is the P-T mass extinction event; the
largest mass extinction in Earth history. This project will attempt to statistically analyse global stratigraphic
changes in trace fossil diversity and occurrences from the start of the Permian through to the end of the
Triassic. This will then be combined with existing data from the Silurian-Carboniferous to gain insights into
how the ichnological record of major extinctions compares with that of ongoing colonization of riverine
ecospace across the boundary between the Palaeozoic and Mesozoic.
Methods
A large amount of published literature has been compiled by the advisor, concerning non-marine facies of
Permian and Triassic age across the world. The student will contribute to this compilation through a
comprehensive literature review, and then systematically trawl the literature for ichnological records. The
data harvested will then be analysed for stratigraphic trends, in conjunction with existing data from SilurianCarboniferous successions, to observe global trends in alluvial trace fossil distribution and occurrences from
the first steps on land, through the assembly of Pangea and the mass extinction events of the late Palaeozoic
and early Mesozoic.
Logistics
The project will be entirely library/office-based, and the student will be provided with all the literature thus
far assembled, and means to collect additional papers.
Reading
Davies, N.S., Gibling, M.R., 2013, The sedimentary record of Carboniferous rivers: Continuing influence of
land plant evolution on alluvial processes and Palaeozoic ecosystems. Earth-Science Reviews, 120, 40-79
(section 7).
Buatois, L.A., Mángano, M.G., Genise, J.F. & Taylor, T.N., 1998, The ichnologic record of the
invertebrate invasion of nonmarine ecosystems: evolutionary trends in ecospace utilization, environmental
expansion, and behavioral complexity. Palaios, 13, 217-240.
Twitchett, R., Barras, C., 2004, Trace fossils in the aftermath of mass extinction events. In: The
Application of Ichnology to Palaeoenvironmental and Stratigraphic Analysis. Geological Society, London,
Special Publications. Vol. 228, 397-418.
Resources
No costs are envisaged, and the student will receive training from the advisor in the collection and
identification of pertinent data.
40
Part III Projects 2016-17
33
Topic:
The Earth’s exhaust pipe: carbon outgassing in arcs (R)
Supervisors:
Marie Edmonds and Sasha Turchyn
Of the total amount of carbon contained in Earth, the mantle is the largest reservoir. Cycling of carbon
between the surface environment and the mantle takes place via carbonate subduction and volcanic
outgassing. Imbalance in this cycle has huge significance for atmospheric CO2 concentration and
consequently atmosphere-ocean temperature over geological timescales. It is important, therefore, to
understand the primary controls on the efficiency of carbonate decomposition into fluids that are driven off
the slab, to be returned to the atmosphere by volcanoes, yet many parts of this cycling are poorly understood
and quantified.
Carbon isotopes, combined with other geochemical tracers, may provide a means to isolate sources and
mechanisms of carbon cycling. Carbonate in subducting slabs may exhibit a wide range in carbon isotopic
signature (relating to inorganic and organic carbon sources). Carbon-bearing fluids generated during
devolatilisation of slabs is expected to be heavy (Mattey, 1991), leaving a light carbon residue on the slab
that may return to the deep mantle (Ague et al., 2014), perhaps recorded in super-deep eclogitic diamonds
(Cartigny, 2005). Volcanic gases from arcs record a range in carbon isotopes, but they are also heavily
affected by crustal contamination, a contribution from mantle wedge volatiles and interaction with
hydrothermal systems.
This project will involve compilation of data on the carbon isotopic composition of volcanic gases (as well
as nitrogen and helium isotopic composition, where available), in order to constrain the sources and
efficiency of carbon cycling in arcs. Data from a range of arcs will be compared to intra-plate and rift
settings in order to understand the effects of crustal contamination and hydrothermal fractionation of carbon.
It is expected that volcanic gases from island arc volcanoes on oceanic crust and submarine arc volcanic
fluids will be of most value. The gas data will be used to construct an understanding of the source of carbon
in arcs and the extent to which carbon is devolatilised from slabs, as well as how carbon isotope
fractionation might operate during devolatilisation.
Ague JJ, Nicolescu S. Carbon dioxide released from subduction zones by fluid-mediated reactions. Nature
Geoscience. 2014 May 1;7(5):355-60.
Cartigny P. Stable isotopes and the origin of diamond. Elements. 2005 Mar 1;1(2):79-84.
Mattey DP. Carbon dioxide solubility and carbon isotope fractionation in basaltic melt. Geochimica et
Cosmochimica Acta. 1991 Nov 30;55(11):3467-73.
Kelemen PB, Manning CE. Reevaluating carbon fluxes in subduction zones, what goes down, mostly comes
up. Proceedings of the National Academy of Sciences. 2015 Jul 28;112(30):E3997-4006.
41
Part III Projects 2016-17
34
Topic:
Defining the first Heinrich events in the North Atlantic
Supervisors:
David Hodell and Alex Piotrowski
Aims
Heinrich Events are large abrupt climate events related to surging of the Hudson Strait ice stream during past
glacial periods. They are marked in North Atlantic deep-sea sediment cores by Heinrich layers that contain
large amounts of ice-rafted detritus (especially detrital carbonate) sourced from Hudson Strait. Although
Heinrich events have been well studied for the last glacial period, few studies have focused on older
Heinrich events during previous glacial periods. Hodell et al. (2008) proposed that Heinrich events began
~640,000 years ago in Marine Isotope Stage 16. This project will examine the earliest Heinrich events (16.1
and 16.2) in detail using a variety of techniques at high resolution (every 5 mm) at Site U1308 located in the
ice-rafted detritus (IRD) belt of the North Atlantic. These events are rich in detrital carbonate but also
exhibit associated low-detrital-carbonate IRD layers that are rich in silicates. What was the source of these
silicate-rich IRD layers and what is their relation to the Heinrich events derived from Hudson Strait? The
provenance will be constrained by Sr and Nd isotopic composition of different size fractions to estimate the
relative contributions of volcanic (Iceland-Faeroes), North America/Greenland, and European sources to the
IRD (Grousset et al., 2001).
Methods
Heinrich Events 16.1 and 16.2 have been sampled at 0.5-cm intervals at Site U1308 in the North Atlantic.
The interval has also been analyzed using CT-Xray and core scanning XRF. The student will groundtruth
these remote-sensing methods with quantitative counts and identification of ice-rafted detritus across the
events. The EDS/Qemscan on the new SEM will be used to aid mineral identification. Geochemical training
will include mineral dissolution, cation chromatography, and isotopic measurements using Thermal
Ionisation Mass Spectrometry (TIMS) and Multi-collector Inductively coupled mass spectrometery (MCICP-MS).
Logistics
Because of the fair amount of analytical work, it would be advantageous for the student to begin during the
summer before the start of Michaelmas term. The project is a good fit for a student interested in isotope
geochemistry and paleoclimatology.
References
Grousset, F.E. et al., (2001), Zooming in on Heinrich layers, Paleoceanography, 16(3), 240-259.
Hodell, D.A., Channell, J.E.T., Curtis, J., Romero, O., and Roehl, U., (2008), Onset of “Hudson Strait”
Heinrich Events in the Eastern North Atlantic at the end of the Middle Pleistocene Transition (~640
ka)?, Paleoceanography, 23, doi:10.1029/2008PA001591.
42
Part III Projects 2016-17
35
Topic:
Understanding the role of ice-sheets in millennial climate variability in the early
Pleistocene
Supervisors:
David Hodell & Alex Piotrowski
Aims
Millennial-scale climate variability was a persistent feature of the climate system even during the “41-kyr
world” of the early Pleistocene when climate boundary conditions differed significantly from “100-kyr
world” of the late Pleistocene. In the “41-kyr world” between 1.5 and 0.65 Ma, ice rafting events were more
frequent than they were in the “100-kyr world”, but Heinrich events were absent from the record (Hodell et
al., 2008). The aim of this project is to characterize ice rafted debris (IRD) events in the early Pleistocene
and determine their provenance at Site U1308 located in the central Atlantic IRD belt. What ice sheets were
involved? How does ice-rafting events relate to millennial-scale climate variability?
The project will examine discrete IRD events from selected glacial cycles of the early Pleistocene. The
number and type of lithic grains will be determined by analysis of the sediment coarse fraction with the aid
of EDS/Qemscan on the new SEM to identify mineralogy of IRD grains. The provenance will be constrained
by Sr and Nd isotopic composition of different size fractions to estimate the relative contributions of
volcanic (Iceland-Faeroes), North America/Greenland, and European sources to the IRD.
Methods
The student will receive training in identification of ice-rafted detritus, including use of the EDS/Qemscan
on the new SEM for mineralogy. Geochemical training will include mineral dissolution, cation
chromatography, and isotopic measurements using Thermal Ionisation Mass Spectrometry (TIMS) and
Multi-collector Inductively coupled mass spectrometery (MC-ICP-MS).
Logistics
Because of the fair amount of analytical work, it would be advantageous for the student to begin during the
summer before the start of Michaelmas term. The project is a good fit for a student interested in isotope
geochemistry and paleoclimatology.
References
Bailey, I., C. T. Bolton, R. M. DeConto, D. Pollard, R. Schiebel, and P. A. Wilson (2010), A low threshold
for North Atlantic ice rafting from “low-slung slippery” late Pliocene ice sheets, Paleoceanography, 25,
PA1212, doi:10.1029/2009PA001736.
Birner, B., Hodell, D.A., Tzedakis, P.C., and Skinner, L.C., (2016), Similar millennial climate variability on
the Iberian margin during two early Pleistocene glacials and MIS 3, Paleoceanography, in press (available
on-line).
Hodell, D.A., Channell, J.E.T., Curtis, J., Romero, O., and Roehl, U., (2008), Onset of “Hudson Strait”
Heinrich Events in the Eastern North Atlantic at the end of the Middle Pleistocene Transition (~640 ka)?,
Paleoceanography, 23, doi:10.1029/2008PA001591.
43
Part III Projects 2016-17
36
Topic:
Three-dimensional reconstruction of sedimentation on the SW Iberian margin during
the last glacial cycle
Supervisors:
David Hodell, Luke Skinner, Simon Crowhurst, Nick McCave
Aims
During 2013, sediment cores were acquired along a transect on a small topographic feature (Promonotorio
dos Prinicipes de Avis) on the SW Iberian margin (Hodell et al., 2014). The cores are arranged along an
onshore-offshore and bathymetric transect with water depths ranging from 600 to 4670 m. High-resolution
XRF core scanning of the cores has revealed a common pattern to elemental variations that can be precisely
correlated among cores (Hodell et al., 2013). The objective of this project is to stratigraphically correlate all
the cores to a common reference frame and timescale. The data will then be gridded to map surfaces (time
horizons) and produce isopach maps to investigate the time-varying patterns of sedimentation on the margin
as a function of changing climate conditions on long and short time scales.
Methods
This is largely a computer-based project that will utilize standard software packages (Analyseries, MatLab,
GIS) to correlate cores, grid data, and create isopach maps. The student will receive training in stratigraphic
correlation, timescale development, and interpretation of sedimentation patterns. The project can also
include some practical experience with XRF scanning of the sediment cores if desired.
Logistics
The core data are available for the student to begin at the start of Michaelmas term (or earlier if desired). The
project is well suited for a student with good computer skills with an interest in stratigraphy, sedimentology,
and paleoclimatology.
References
Hodell, D.A., Elderfield, H., Greaves, M., McCave, I.N., Skinner, L., Thomas, A., White, N., and the JC089
Scientific Party, 2014. JC089 Cruise Report -- IODP Site Survey of the Shackleton Sites, SW Iberian
Margin, British Ocean Data Centre, Available at:
https://www.bodc.ac.uk/data/information_and_inventories/cruise_inventory/report/13392/
Hodell, D.A., Crowhurst, S., Skinner, L., Tzedakis, P.C., Margari, V., Channell, J.E.T., Kamenov, G.,
Maclachlan, S., and Rothwell, G., 2013. Response of Iberian Margin sediments to orbital and suborbital
forcing over the past 420 ka. Paleoceanography, 28, 1–15, doi:10.1002/palo.20017.
44
Part III Projects 2016-17
37
Topic:
Modern sediment and isotopic properties on the Portuguese margin in relation to
Atlantic Ocean hydrography.
Supervisors:
David Hodell, Nick McCave, Luke Skinner
Aims
At the Portuguese continental margin the benthic foraminifera record an oxygen isotopic history resembling
temperature in Antarctic ice cores whereas planktonic foraminifera give a record resembling Greenland’s
climate history (Shackleton et al., 2000). In addition the area is bathed in NE Atlantic Deep Water and
Mediterranean Outflow Water with southern source water below 3,500 m. In 2013, we obtained a highquality set of surface sediment samples from 15 sites down the SW Portuguese margin from water depths of
405 to 4670 m (Hodell et al., 2014). For each site we have measurements of temperature and salinity
throughout the water column. We also have bottom water and pore water samples. The aim is to find out
how the common proxies for temperature (18O) and flow speed (silt size SS ) and water mass identity (13C
in foraminifera and possibly other tracers) in core tops relate to the properties of the different Atlantic water
masses encountered.
Methods
The tasks involved in which training will be given include measurement of basic sediment properties –
carbonate, silica and organic carbon content, grainsize -, picking benthic and planktonic forams for
measurement of 18O and 13C, and measurement of these isotopic ratios on corresponding water samples.
These properties will be related to one another – proxy to water property – and set in the context of the
regional oceanography. The advantage of this set for a Part III project is that there are only 15 samples, but
an exciting array of techniques that can be applied to them. If time permits there is scope for adding a time
dimension by studying downcore at one of the sites.
Logistics
The samples will require several weeks of physical and chemical processing which can be done before the
student departs for the summer holiday, or over the summer. The student should have a complete data
midway through Michaelmas term for data analysis and writing. The project is for a student with interest in
paleoclimatology.
Resources
It will be an advantage if the student can stay in residence immediately after the end of Easter Term to do the
sample preparation and foram picking so that running the samples can be scheduled with a good lead-time.
Reading
Daniault, N., Maze, J.P. & Arhan, M., 1994, Circulation and mixing of Mediterranean Water west of the
Iberian Peninsula. Deep-Sea Research I, 41, 1685-1714.
Hodell, D.A., Elderfield, H., Greaves, M., McCave, I.N., Skinner, L., Thomas, A., White, N., and the JC089
Scientific Party, 2014. JC089 Cruise Report -- IODP Site Survey of the Shackleton Sites, SW Iberian
Margin, British Ocean Data Centre, Available at:
https://www.bodc.ac.uk/data/information_and_inventories/cruise_inventory/report/13392/
Shackleton, N. J., M. A. Hall, & E. Vincent (2000), Phase relationships between millennial-scale events
64,000–24,000 years ago, Paleoceanography, 15, 565–569.
van Aken, H. 2000, The hydrography of the mid-latitude northeast Atlantic Ocean I: The deep water masses,
Deep Sea Res., Part I, 47, 757– 787: II: The intermediate water masses, ibid, 789– 824.
Voelker, A.H.L., Colman, A., Olack, G., Waniek, J.J., and Hodell, D.A., 2015. Oxygen and Hydrogen
isotope signatures of northeast Atlantic water masses, Deep-Sea Research II,
http://dx.doi.org/10.1016/j.dsr2.2014.11.006
45
Part III Projects 2016-17
38
Topic:
The Cause of Colour Variations in Iberian Margin Sediment Cores
Supervisors:
David Hodell, Luke Skinner, Sasha Turchyn, Simon Crowhurst
Aims
This project will study the factors influencing sediment colour in a suite of sediment cores recently collected
on a research cruise (JC089) to the Iberian Margin (Hodell et al., 2014). During the cruise, we recovered
undisturbed transitions from the surface oxidized layer into reducing sediment in a series of multi-cores and
piston cores at different water depths on the Iberian Margin. The student will characterize these colour
variations using digital core images and spectrophotometry. The objective is to link changes in colour
reflectance to changes in mineralogical/chemical composition of the sediment and interpret past variations in
the source and supply of terrigenous and biogenic sediment to the Iberian Margin across the last
deglaciation. The digital images have a full resolution of 10 pixels per mm and thus offer the potential for
detecting high-frequency climatic variations at an unprecedented temporal resolution.
Methods
The student will use a portable colour spectrophotometer (Minolta CM-700d) that measures light reflected
from the sediment surface that is fed to a series of optical fibers that divides the wavelength into 10-nm bins
for the visible part of the spectrum (400-700 nm). Methods will include spectrophotometry and image
processing using ImageJ software, an open-source Java™ based program. Other methods include: XRD for
mineralogical identification, coulometric titration for carbonate content, and CNS elemental analyzer for
organic carbon, and wet chemistry for Fe2+/Fe3+.
Logistics
All the cores and equipment needed for this study are housed in the Department of Earth Sciences. The
project is well suited for a student with interests in sedimentology, geochemistry, and palaeoclimatology.
References
Giosan, L., Flood, R.D., Aller, R.C., 2002. Paleoceanographic signi¢cance of sediment color on western
North Atlantic drifts: I. Origin of color. Marine Geology, 189, 25-41.
Hodell, D., S. Crowhurst, L. Skinner, P. C. Tzedakis, V. Margari, J. E. T. Channell, G. Kamenov, S.
Maclachlan, and G. Rothwell (2013), Response of Iberian Margin sediments to orbital and suborbital forcing
over the past 420 ka, Paleoceanography, 28, doi:10.1002/palo.20017.
Hodell, D.A., Elderfield, H., Greaves, M., McCave, I.N., Skinner, L., Thomas, A., White, N., and the JC089
Scientific Party, 2014. JC089 Cruise Report -- IODP Site Survey of the Shackleton Sites, SW Iberian
Margin, British Ocean Data Centre, Available at:
https://www.bodc.ac.uk/data/information_and_inventories/cruise_inventory/report/13392/
Rogerson, M., Weaver, P.P.E., Rohling, E.J., Lourens, L.J., Murray, J.W., and Hayes, A., 2006. Colour
logging as a tool in high-resolution palaeoceanography. In: Rothwell, R.G., New Techniques in Sediment
Core Analysis. Geological Society, London, Special Publications, 267, 99–112
46
Part III Projects 2016-17
39
Topic:
Trace element and isotope geochemistry of gypsum: constraining the marine vs.
nonmarine debate (L)
Supervisors:
Sambuddha Misra, Aleksey Sadekov, and David Hodell
Aims
It is important to identify the origin of evaporate minerals (i.e., marine vs. continental) for better
understanding of ancient hypo-saline, saline and hyper-saline environments. The conventional geochemical
methods cannot clearly distinguish between marine and nonmarine sources of evaporative minerals. This
limits our understanding of the paleo-environmental setting during evaporite mineral formation. For
example, application of strontium and sulfur isotopes classifies the Primary Lower Gypsum of the Messinian
Salinity Crisis as dominantly marine (e.g. Lu and Meyers, 2003); however, such one dimensional
interpretation significantly underestimates the contribution of fresh water for certain horizons (Evans et al.
2015).
The concentration and isotopic composition of both boron and lithium of the continental crust and seawater
are distinctly different. This allows the use of these two isotope systems to potentially constrain the origin of
evaporite minerals (Vengosh et al. 1992). However, the lack of knowledge regarding how the isotopes of
lithium and boron fractionate during the crystallization processes of gypsum limits its application.
This project will aim to constrain the isotope fractionation factors, the distribution coefficient of the light
stable isotopes, and the composition of primary fluid inclusions using a range of new and novel geochemical
tools.
Methods
The student will create mixing experiments to determine the incorporation of boron and lithium isotopes into
gypsum and their associated fractionation factors with regard to the coeval brines. The student will examine
how these vary with differing parameters such as temperature, growth rate and pH. Analysis of the
precipitated solids and brines via Element ER Mass Spectrometry will determine how this information can
be used to fingerprint the source fluid of natural samples. The student will also use laser ablation ICP-MS to
determine the composition of fluid inclusion in natural samples and how they relate to the fluids in which
they grew.
Logistics
The student should be available 4 weeks prior to the start of term to commence with lab work and training.
The costs associated with the isotope and geochemical analyses will be covered through existing funding.
Reading
Evans, N.P., Turchyn, A., Gázquez, F., Bontognali, T.R.R., Chapman, H.J., and Hodell, D.A., 2015.
Coupled measurements of δ18O and δD of hydration water and salinity of fluid inclusions in gypsum from
the Messinian Yesares Member, Sorbas Basin (SE Spain), Earth Planet. Sci. Lett. 430, 499-510
Lu, F.H., and Meyers, W.J., 2003. Sr, S, and OSO4 isotopes and the depositional environments of the Upper
Miocene evaporates, Spain. Journal of Sedimentary Research 73, 444-450.
Vengosh, A., Starinsky, A., Kolodny, Y., Chivas, A.R., Raab, M., 1992. Boron isotope variations during
fractional evaporation of seawater: new constraints on the marine vs. nonmarine debate. Geology 20, 799802.
47
Part III Projects 2016-17
40
Topic:
Supervisor:
Micro-Raman Studies of Barite at High Pressure and High Temperature Conditions
Sébastien Facq and Simon Redfern ([email protected])
Aims
Sulfates are among the most common minerals in the Earth’s crust. However, the stability of sulfate minerals
at high pressure and temperature conditions relevant to deep crustal and lower mantle is poorly constrained.
The aim of this study is therefore to undertake an experimental study of barite, BaSO4, at pressure and
temperatures corresponding to the deep Earth. Barite has been identified previously in Earth’s crust but also
in meteorites, with potential implications for its occurrence in proto-planetary bodies. Experimental work
will be particularly devoted to understanding the structural response of barite to pressure and temperature,
revealed in the evolution of its vibrational modes. The effects of pressure or temperature on vibrational mode
frequencies will be expressed using the classical mode Grüneisen parameter and its isobaric equivalent.
Methods
High pressure (up to 10 GPa) and high temperature (up to
500°C) behavior of barite will be investigated using in situ
Raman spectroscopy coupled to a Membrane-type Diamond
Anvil Cell (MDAC) and a dedicated LinkamTM DSC 600
heating stage, respectively. The collected Raman spectra will
be used to obtain the evolution of the vibrational modes of
barite with pressure and temperature, estimate the Grüneisen
parameter and its isobaric equivalent to finally calculate the
anharmonic parameter ai for each observed mode. These
results will enable modelling of the potential stability and
occurrence of barite in the deep Earth, and its possible role
volatile in the lower crust and upper mantle.
then
Mineral sample is located in a 200µm hole
drilled in a thin leaf of steel (gasket)
squeezed between two diamonds (anvils).
as a
Logistics
The experiments will take place at the recently-re-established high-P/T diamond anvil cell laboratory in the
Department of Earth Sciences. Resources exist for the experimental programme. The project requires
approximately 50% time completing the experiments and 50% carrying out data treatment and interpretation
and is suitable for a student interested in deep Earth petrology, geophysics, geochemistry and high pressure
sciences.
References
Chen, Y-H., Huang, E. and Yu, S-C. (2009) High-pressure Raman study on the BaSO4-SrSO4 series, Solid
State Communications, 149, 2050-2052.
Crichton, W. A., Merlini, M., Hanfland, M. and Müller, H. (2011) The crystal structure of barite, BaSO 4, at
high pressure, American Mineralogist, 96, 364-367.
Santamaria-Pérez, D. et al.(2011) High-pressure of the behavior of mineral barite by X-ray diffraction,
Physical Review B, 84, 054102.
48
Part III Projects 2016-17
41
Topic:
Using Principal Component Analysis of X-ray diffraction data to quantify mineral mixtures
Supervisor:
Giulio Lampronti and Simon Redfern ([email protected])
Aims
X-ray diffraction has been used for over one century to characterise mineral compositions. Today it is a
widely-used method for identifying and quantifying the crystalline materials in natural and synthetic
powders. Applications range from the pharmaceutical industry, through the mineral resource and functional
materials communities, to understanding the complex mineral composition of any rock type. Here, we aim to
develop a new and efficient method for identification and quantification of mineral mixtures by X-ray
diffraction. The approach relies on principal component analysis (PCA) rather than more traditional
structural fitting methods, which are computationally intensive and require a high degree of operator
interpretation. Furthermore, it will use multivariate analysis to develop calibration methods automatically.
Methods
We have an existing library of X-ray diffraction data collected over several years and analysed by traditional
methods to give quantified estimates of mineral compositions. The samples were clay-rich sediments and
clay fractions, of interest to the oil and gas industry and important in understanding reservoir maturity. The
student will apply existing MatLab and/or R PCA libraries to build a method for analysis of X-ray datasets.
The output will be estimates of mineral phase identification and composition to provide a “black box” userindependent quantification of the sample. The results will be compared with the prior quantifications made
by traditional approaches. The project will have the potential for application to new sample suites and
datasets that have not been studied previously, and could also develop towards a freeware or
commercialisable process for widespread application in materials characterisation.
Logistics
The datasets on which the student will work are already available within the Department. The student will
have access to computing facilities within the Department. X-ray diffraction experiments and sample
preparation will be carried out under the supervision of Dr Lampronti and will require training in appropriate
safety and laboratory practise.
References
de Oliveira, T F, E K Epprecht, R L Ziolli, A C F Saraiva and R R de Avillez (2007) Multivariate calibration
by partial least squares for the quantitative phase analysis using Rietveld method. Chemometrics DOI:
10.1002/cem.1128
Caliandro, R, G Di Profio, O Nicolotti (2013) Multivariate analysis of quanternary carbamazepine-saccharin
mixture by X-ray diffraction and infrared spectroscopy. J Pharmaceutical Biomedical Analysis 78-79, 269279 DOI: 10.1016/j.jpba.2013.01.042
49
Part III Projects 2016-17
42
Topic:
Structure/property relationships of mollusc shells as natural biocomposite materials (L)
Supervisors:
Liz Harper and Michael Carpenter
The evolution of bivalve shells has been marked by increasing complexity of microstructure and organic
content, while brachiopod shells have remained rather conservative in their construction. The shells of both
groups are composite materials in which stiff but brittle calcite and/or aragonite crystals and soft but flexible
organic components combine, presumably to optimise strength and flexibility in respect to plastic and elastic
deformation which may be induced by predators and the physical environment. Early studies on bivalve
shells have suggested that many are mechanically strong but that different microstructural arrangements
have very different properties. Surprisingly, however, many of the bivalves seem to have evolved ‘weaker’
shells. Since then there have been substantial advances in the experimental techniques available for
measuring elastic properties of small samples.
Recent projects by Part III student have demonstrated that the elastic properties of bivalve shells can be
determined by conventional mechanical testing methods, including four point bending and compression of
arched specimens. These have shown that the Young’s modulus, E, of macroscopic specimens sawn from
the shells and of the whole shells themselves differ between species. In addition, it was found that there does
not appear to be a systematic dependence of E on microstructure. These results have been compounded by
nanoindentation data, following a newly devised protocol which ensures that the organic component remains
hydrated. The overall elastic behaviour depends on the shells behaving as composite materials in which the
organic component is elastically soft (E ~ 1-5 GPa) and the carbonate matrix is stiff (E ~ 50-80 GPa) to give
overall values of E ~ 10-30 GPa. A substantial advance in our understanding of these results has come from
the most recent project, in which X-ray tomography was used for the first time to produce a true 3d
representation of the distribution of organic matter and inorganic matrix, coupled with finite element
analysis of the mechanical properties. The purpose of this project will be to extend this overall approach to
elastic properties and brittle failure to a wider range of molluscs.
The elastic properties of a variety of mollusc shells will be measured by nanoindentation and four point
bending, to identify how microstructure determines the bulk properties. Selected samples will then be used
for detailed investigation by X-ray tomography and finite element analysis.
The broader objective is to understand the relationship between microstructure, environment and
evolutionary history of the organisms, since the physical properties of their shells are likely to be a
significant part of their ecology.
The project will be entirely lab-based and will involve interdisciplinary collaboration – applying techniques
developed for materials science to biological systems. It will be possible to start the project in the vacation,
if the student chooses to do so. Training will be provided in the four main techniques to be used
(nanoindentation, SEM, theromgravimetric analysis and X-ray tomography). No prior knowledge of any of
the techniques is required. (NOTE: X-ray tomography will require particular help from an expert in
Materials Science. The extent to which access to equipment and suitable help can be assured, will be
reviewed nearer the time).
Esteban-Delgado, F.J., E.M.Harper, A.G.Checa, A.B.Rodriguez-Navarro (2008) Origin and expansion of
foliated microstructure in pteriomorph bivalves. Biological Bulletin 214, 153-165.
Bignardi, C., M.Petraroli, N.M.Pugno (2010) Nanoindentations on conch shells of Gastropoda and Bivalvia
molluscs reveal anisotropic evolution against external attack. Journal of Nanoscience and Nanotechnology
10, 6453-6460.
Merkel, C., J.Deuschle, E.Griesshaber, S.Enders, E.Steinhauser, R.Hochleitner, U.Brand, W.W.Schmahl
(2009). Mechanical properties of modern calcite- (Mergerlia truncata) and phosphate-shelled brachiopods
(Discradisca stella and Lingula anatina) determined by nanoindentation. Journal of Structural Biology 168,
396-408. 29 Project Guide 2014-15
50
Part III Projects 2016-17
43
Topic:
Eocene predator-prey interactions : a comparison between the high and mid latitudes
Advisors:
Liz Harper & Alistair Crame (British Antarctic Survey)
Aim
Predation is a key driver in the evolution of shelly benthic organisms. Although many forms of predation are
untraceable in the fossil material, the record of predatory drill holes in shells provides a wealth of evidence
that may be quantify a variety of aspects this behaviour (e.g. prey ‘choice’, predator effectiveness, size
selectivity and handling preferences) and results compared over different spatial and temporal scales. The
majority of studies concentrate on North American or Western European localities and chiefly concern low
of temperate latitude sites. This project will compare data on to be collected from the rich Eocene shelly
faunas of La Meseta Formation (LMF) , Seymour Island (Antarctica) deposited at high southern
palaeolatitudes and the Paris Basin deposited in the temperate part of the northern hemisphere.
Methods
The British Antarctic Survey houses a large collection of well preserved molluscs from the LMF whilst the
Sedgwick Museum has similar holdings from the Paris Basin. The student will screen each of these
collections for predatory drill holes made by both gastropods and octopus and collect morphometric and
positioning data which will allow them to establish prey preferences, various aspect of predator behaviour
and identify ‘successful’ prey where drilling ends in failure. The student will learn appropriate statistical
techniques to compare data between taxa to examine the effect of size, thickness, ornamentation and life
habit on successful and unsuccessful predatory attempts and also to compare findings between the higher
and lower latitude sites.
Logistics and resources
The project requires use of existing museum collections and basic laboratory equipment available in both
Earth Sciences and the British Antarctic Survey. It may be necessary for the student to do some preparation
of specimens to remove matrix and some use of the scanning electron microscope may be required to image
octopus drill holes. No extra funds are required,
Reading
Harper, E.M. (2006) Dissecting the post-Palaeozoic arms race.
Palaeogeography, Palaeoclimatology, Palaeoecology 232:322-343.
Todd, J.A. & Harper, E.M. (2011). Stereotypical boring behaviour inferred from the earliest known octopod
feeding traces: Early Eocene, southern England. Lethaia 44: 214-222.
51
Part III Projects 2016-17
44
Topic:
Timescales of magma storage and transport in the Krafla volcanic system
Supervisor:
John Maclennan, Euan Mutch
Aims
The Krafla fires were a series of basaltic fissure eruptions that took place in Iceland in a series of episodes
between 1977 and 1984. They were one of the first set of basaltic eruptions to have been subject to the
scrutiny of volcano monitoring by seismic and geodetic observations. A number of similar fissure eruptions
have occurred in the Krafla volcanic system over Holocene times. These eruptions carry a small proportion
of phenocrysts, macrocrysts and gabbroic nodules. The aim of this project is to use the textural and
compositional properties of the crystal cargo to constrain the timescales of crystal residence in the magmatic
system prior to eruption, and to understand how these timescales relate to the geophysical observations that
track magma movement in the Krafla system.
Methods
A sample set of suitable crystals and gabbroic nodules is already available from the Krafla system. The
student may prepare thin sections and grain mounts to enable further study of these samples. The student
will carry out a textural analysis of the samples, such as calculating crystal size distributions and estimating
the aspect ratios of the plagioclase crystal to constrain cooling rates. A number of QEMSCAN/SEM
elemental maps and electron probe profiles will be acquired. These maps and profiles will be modelled by
the student using a new FEniCS finite element code in the Python language. This code has been developed
by Euan Mutch and models the diffusion of elements such as Mg in plagioclase. Ideally this code will be
extended by the student to encompass specific aspects of the Krafla system. A combination of the new
observations and modelling will provide new constraints on timescales between crystal growth and eruption.
Logistics
If the student wishes to undertake fieldwork in Iceland, that will take place in the summer of 2016, at
localities decided in discussion with the supervisor. Sample preparation and electron probe microanalysis
will take place in the Department, with guidance from technical experts. The development of the models will
require the student to learn to code in a suitable language, probably Python, and the supervisor will assist
with those choices.
Finance
Funding for fieldwork may be partly obtained by the student. Support for related summer work in the Harker
Collection may also be available. Funds are available to support the sample preparation and micro-analysis.
Database manipulation and model development have no costs.
Reading List
Costa, F. & Morgan, D. (2010) Time Constraints from Chemical Equilibration in Magmatic Crystals, in
Timescales of Magmatic Processes: From Core to Atmosphere (eds A. Dosseto, S. P. Turner and J. A. Van
Orman), Wiley, doi: 10.1002/9781444328509.ch7
Hollingsworth, J., et al., (2013) New constraints on dike injection and fault slip during the 1975-1984 Krafla
rift crisis, NE Iceland, Journal of Geophysical Research, 118, 3707-3727.
Holness M.B. (2014). The effect of crystallization time on plagioclase grain shape in dolerites. Contributions
to Mineralogy and Petrology 168, 1076.
52
Part III Projects 2016-17
45
Topic:
Further constraints on mantle temperatures from olivine-spinel thermometry
Supervisor:
John Maclennan, Simon Matthews, Oli Shorttle, Marie Edmonds
Aims
A long-standing goal of igneous petrology has been to link the composition of primitive melts to the
potential temperature of their mantle source regions. One approach to this problem has involved the use of
thermometers based upon olivine-liquid equilibrium. This method provides estimates of the temperature of
crystallisation of primitive melts in deep magma chambers. If information about the depth of crystallisation,
extent of mantle melting and thermodynamic properties of the melt and mantle are available, then the
crystallisation temperature can then be converted into an estimate of mantle potential temperature. A large
number of assumptions are involved in generation of these temperature estimates and the aim of this project
is to build on the successful Part III project of Simon Matthews in order to estimate mantle potential
temperatures with meaningful uncertainties in a range of settings (e.g. Icelandic flank zones, Hawaii,
Reykjanes Ridge).
Methods
A large dataset of Icelandic, Reykjanes Ridge and Hawaiian olivine and spinel compositions has previously
been compiled and it is hoped that, by sampling and subsequent micro-analysis, the student will be able to
add high-quality data to this compilation. The student will perform the thermometry of crystallisation. They
will then further develop models to explore how sensitive the estimates of potential temperature are to
variation in the conditions of melting and the lithology of the mantle source. By comparison of the model
results with the observations, it is hoped that they will be able to provide robust estimates of mantle potential
temperature variations.
Logistics
If the student wishes to undertake fieldwork in Iceland, that will take place in the summer of 2016, at
localities decided in discussion with the supervisor. Sample preparation and electron probe microanalysis
will take place in the Department, with guidance from technical experts. The development of the models will
require the student to learn to code in a suitable language, probably Python, and the supervisor will assist
with those choices.
Finance
Funding for fieldwork may be partly obtained by the student. Support for related summer work in the Harker
Collection may also be available. Funds are available to support the sample preparation and micro-analysis.
Database manipulation and model development have no costs.
Reading List
Putirka, K. et al., (2007). Ambient and excess mantle temperatures, olivine thermometry, and active vs.
passive upwelling. Chemical Geology, 241, 177-206.
Herzberg, C. et al., (2007). Temperatures in ambient mantle and plumes: Constraints from basalts, picrites,
and komatiites. Geochemistry Geophysics Geosystems, 8, doi: 10.1029/2006GC001390.
Shorttle, O. & Maclennan, J. (2011) Compositional trends of Icelandic basalts: Implications for shortlengthscale lithological heterogeneity in mantle plumes. Geochemistry Geophysics Geosystems, 12 .
Q11008.
Coogan L. et al., (2014, in press) Aluminum-in-olivine thermometry of primitive basalts: evidence of an
anomalously hot mantle source for large igneous provinces, Chemical Geology.
53
Part III Projects 2016-17
46
Topic:
Non traditional stable isotope fractionation between silicate melts and minerals (F,L)
Supervisors:
Ed Tipper, Marian Holness
Summary
One key recent finding in magnesium stable isotopes (24Mg, 25Mg, 26Mg) is that there is significant intermineral fractionation at high temperatures, in particular between the Mg bearing phases, pyroxene, olivine,
spinel and garnet. Some workers have used this to try and develop new thermometers and have related the
fractionation factors to bond strength associated with coordination in a mineral lattice. However, it is far
from clear what exactly these natural fractionations represent. Do they represent fractionation between a
crystal and a liquid? Do they represent sub-solidus re-equilibration and diffusion? The answer will have
important implications for our understanding of the stable isotope compositions of both igneous and
metamorphic rocks, and in turn for the isotopic compositions of the bulk silicate Earth. This project will
work on cumulate rocks where minerals that have crystalised from a liquid, and settled to the base of a
magma chamber, without substantial re-equilibration and determine whether there is an isotopic
fractionation between a melt and crystallising phase in natural samples.
Methods
The student will collect samples from olivine and spinel bearing cumulate sequences in northern Skye,
requiring about 1 week of fieldwork in the early summer of 2016. Thin sections will be made, and
individual mineral separates picked from crushed samples. The student will then learn the preparation
required for Mg isotope analysis to be conducted by state-of-the-art MC-ICP-MS in the isotope
geochemistry labs in Cambridge. A significant part of this work will need to be conducted during the
summer vacation period due to the relatively intensive nature of the sample preparation and analysis. In
tandem, the student will conduct a literature compilation of silicate mineral Mg isotopes and their origins.
Resources
The student will need to apply for subsistence and travel costs for field work (total cost likely c. £500
depending on accommodation preferences). Access to a car would be essential.
Reading
Young et al, 2009, Spinel–olivine magnesium isotope thermometry in the mantle and implications for the
Mg isotopic composition of Earth, EPSL, 288 524-533.
Liu et al, 2011, High-temperature inter-mineral magnesium isotope fractionation in mantle xenoliths from
the North China craton, EPSL, 2011, 308, 131-140
54
Part III Projects 2016-17
47
Topic:
Himalayan chemical weathering and carbon transfer triggered by the April 2015
Nepal Earthquake (L, F)
Supervisors:
Ed Tipper, Mike Bickle
Summary
The magnitude 7.8 (25/4/15) and 7.3 (12/5/2015) earthquakes in Nepallast year triggered thousands of
landslides which will cause major perturbations to sediment and chemical loads carried by the local
Himalayan rivers. The objective of this part III project is to quantify the impact of this ∼100 year event on
inorganic and organic carbon fluxes exported from this part of Nepal. This will determine the impact of such
major events on the cation fluxes thought to moderate long-term climate change. The Narayani and Kosi
rivers which drain the earthquake-hit area carry > 40% of the total bicarbonate flux input to the Ganges from
the Himalayan mountains. Recent work has demonstrated that weathering in areas with the highest physical
erosion rates are the most sensitive to climatic feedback parameters (both rainfall and temperature) because
they are not limited by a supply of material. The Himalayan region is central to this work because of 1) the
high erosion rates, 2) high monsoonal rainfall, and 3) high temperatures in the Ganges plain in front of the
main range, where much of the weathering takes place. In the months following the earthquakes we
collected samples, and as part of this Part III project we will return to Nepal to complete our sampling.
Methods
The student will assist in the collect of river water/suspended sediment samples in the Nepal sub-Himalaya
for a two to three week period most likely in June/July. Upon return to Cambridge the water samples will
be analysed for cations and anions, and the sediments for major elements by XRF. The student will conduct
the analyses and interpret the data in the context of the samples collected last summer and an archive of data
in the literature from before the earthquakes.
Funding
Much of the funding for the fieldwork can be provided from an existing grant, but if the student can
contribute to this via travel grants this would be a significant benefit to cover visa, travel vaccinations as
well as some travel and accommodation.
Reading
Jin et al, 2015, Controls on fluvial evacuation of sediment from earthquake-triggered landslides Geology, 43,
115-118.
Jin et al, 2015, Seismically enhanced solute fluxes in the Yangtze River headwaters following the A.D. 2008
Wenchuan earthquake, Geology, 44, 47-50
55
Part III Projects 2016-17
48
Topic:
Climate dependency of Li isotope fractionation during weathering (L)
Supervisors:
Ed Tipper, Alex Piotrowski, Ruth Hindshaw
Summary
The chemical weathering of silicate rocks is a key feedback mechanism for the stabilisation of Earth’s
climate, by regulating the carbon cycle. The primary aim of the proposal is to constrain how chemical
weathering processes, and in particular chemical weathering intensity, respond to rapid climate change
(millennial time-scales). The areas on Earth most susceptible to rapid climate change are those at high
latitudes and therefore these regions are where sensitivity to the feedback between silicate weathering and
climate is greatest. The high sensitivity is not only due to the current rapid increase in temperature, but also
to the waxing and waning of ice-sheets, which have a profound effect on the surface exposure of rock and
additionally grinds the rock to a fine powder making it highly reactive. Li isotope ratios are one of the most
promising tracers of chemical weathering that have emerged over of the last decade. They show large
variation linked to the formation of clays during weathering, and the weathering intensity.
This project
will determine whether there is a climatic dependence of Li isotope ratios during weathering in the Artic by
measuring Li isotopes in selected clays in an ODP core (909) off-shore Svalbard.
.
Methods
The student will work on detrital clays from ODP core 909, and will learn how to process a small but
carefully selected set of samples for Li isotope analysis by state-of-the-art MC-ICP-MS in the isotope
geochemistry labs in Cambridge. This will be used to evaluate the change in weathering intensity between
glacial/interglacial periods. Changes in sources will be assessed by Nd isotopes or REE patterns. A
significant part of this work will need to be conducted during the summer vacation period due to the
relatively intensive nature of the sample preparation and analysis. In tandem, the student will conduct a
literature compilation Li isotopes in the weathering environment and develop quantitative models for their
interpretation.
Reading
Misra and Froelich, 2012, Lithium Isotope History of Cenozoic Seawater: Changes in Silicate Weathering
and Reverse Weathering, Science, 335, 818-823.
Tipper et al, 2012, Positive correlation between Li and Mg isotope ratios in the river waters of the
Mackenzie Basin challenges the interpretation of apparent isotopic fractionation during weathering, EPSL,
333, 35-40.
56
Part III Projects 2016-17
49
Topic:
Deep crustal processing of primary melts beneath Continental Flood Basalts Provinces
Advisor:
Dr Sally A Gibson
Aims
Continental flood basalts (CFBs) represent the culmination of the largest melting events that occur in the
Earth’s convecting mantle and are widely linked to the sub-lithospheric impact of upwelling mantle plumes
generated at the. The high mantle temperatures (TP=1550 oC) generate primary melts with high MgO
contents (picrites) but the surface expression of these events is vast outpourings of basaltic lava. The
findings of petrological1, experimental2, numerical and seismic3 studies all indicate that greater than 50% of
the melt generated during CFB events is trapped in the crust and forms large mafic cumulate bodies
(ol+cpx+opx) at the MOHO. This is a result of primitive magmas ponding and undergoing high-pressure
crystal fractionation until they become sufficiently buoyant to ascend to the surface, usually as basaltic
magmas. Picrites rarely reach the Earth’s surface but have been found near the base of the several CFB
provinces (e.g. Karoo, British Tertiary and Parana-Etendeka). Despite the uniformity in compositions
predicted for primitive CFB melts a paradox exists between the observed and predicted phase assemblages
of picrites and cumulate assemblages, specifically with respect to the presence or absence of orthopyroxene.
The main goal of this project is to understand the crustal processing that occurs beneath CFB provinces and
how this influences the compositions of erupted melts.
Methods
The project will focus on textural and compositional variations of mineral phases present in picrites from
CFB provinces (Karoo and Parana-Etendeka4,5). The major-element compositions of phenocrysts phases will
be examined by electron microprobe. Trace element concentrations will be analysed at the nanoscale by
state-of-the-art laser-ablation inductively-coupled mass spectrometry (LA-ICP-MS). These will provide
information on element partitioning which is key to understanding the processes occurring in magma
chambers6, such as fractionation and replenishment, and melt transport. The results will be compared with
those predicted from numerical models of crystal fractionation, e.g. MELTS (http://melts.ofm-research.org/)
and Petrolog (www.geol.utas.edu.au/~leonid/).
Logistics
The necessary samples are available in SAG’s existing collection. 5 days on the electron microprobe and 3
days on the LA-ICP-MS will be required. Appropriate laboratory and library facilities are available in
Cambridge.
Resources
The student will require thin-sectioning facilities, use of a petrological microscope, electron microprobe,
LA-ICP-MS, computers and the library.
Reading
1.
Gibson, S. A. Ferropicrites: geochemical evidence for Fe-rich streaks in upwelling mantle plumes.
Earth Planet. Sci. Lett. 174, 355–374 (2000).
2.
Thompson, R. N. Primary basalts and magma genesis. Contrib. Mineral. Petrol. 45, 317 (1974).
3.
Ridley, V. A. & Richards, M. A. Deep crustal structure beneath large igneous provinces and the
petrologic evolution of flood basalts. Geochem. Geophys. Geosyst. 11, 21 PP. (2010).
4.
Cox, K. G. & Jamieson, B. G. The Olivine-rich Lavas of Nuanetsi: a Study of Polybaric Magmatic
Evolution. J. Petrology 15, 269–301 (1974).
5.
Cox, K. G. Postulated restite fragments from Karoo picrite basalts: their bearing on magma
segregation and mantle deformation. Journal of the Geological Society 144, 275–280 (1987).
6.
Liang, Y., Sun, C. & Yao, L. A REE-in-two-pyroxene thermometer for mafic and ultramafic rocks.
Geochimica et Cosmochimica Acta 102, 246–260 (2013).
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Part III Projects 2016-17
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Topic: Controls on the sulfur isotopic composition of the mantle (L)
Supervisors:
Marie Edmonds, Sasha Turchyn and Sally Gibson
Sulfur is an important volatile element in magmas and occurs as sulfide or as dissolved sulfur, partitioning
into hydrous vapor as magmas ascend towards the surface and erupt. Sulfur outgassing during volcanic
eruptions has had a fundamental control on the oxygenation of our atmosphere and on the origins of life on
Earth at hydrothermal vents. Sulfur isotopes allows some constraints to be placed on solid Earthbiochemical-atmosphere cycling of sulfur. “Primordial” sulfur, as contained in meteorites, has a δ34S value
of 0 +/-0.5‰ and has been assumed previously that mantle sulfur fell within a narrow range of compositions
around 0‰. A large range of volcanic and intrusive rocks from a range of settings however, contain
significantly heavier sulfur, with a composition of up to +20.7‰. For example, sills and lavas from the
Siberian Traps contain sulfur with a δ34S of up to +8‰. One possibility is that all of these magmas have
assimilated large quantities of crustal sulfur (e.g. sulfur-bearing sediments like oil shale or evaporite).
Another possibility is that mantle sulfur is heterogeneous in composition, perhaps inherited from subducted
components (altered oceanic crust and sediments). This latter possibility is supported by δ34S values of up to
+9 +/-1‰ for sulfide inclusions in sub-continental diamonds. Some recent work on Siberian and Mongolian
xenoliths have suggested that the mantle beneath the continents might be relatively sulfur-poor with a heavy
sulfur isotope signature, caused by large degrees of depletion or by progressive metasomatism.
This project will investigate these hypotheses by analysing the sulfur content and sulfur isotopic composition
of a suite of well-characterised mantle xenoliths from the Kaapvaal Craton, South Africa. This project will
involve the geochemical and textural characterisation of sulfides within the xenolith samples, using scanning
electron microscopy, QEMSCAN and mass spectrometry for sulfur concentrations and isotopic composition.
The composition of the sulfides and the sulfur concentration will be compared to indices of metasomatism
from bulk rock geochemistry (concentration of LILE, Sr isotopes, trace element ratios) and used to make
inferences about how sulfur behaves during partial melting and during interaction with small fraction melts
in the mantle. The analytical work will be accompanied by a full literature review of the topic, collating all
sulfide data: from inclusions in diamonds to sulfides in lavas and xenoliths. The results will contribute to
ongoing debate about the origin of heavy sulfur signatures in igneous rocks.
Winterburn, Peter A., Ben Harte, and John J. Gurney. Peridotite xenoliths from the Jagersfontein kimberlite
pipe: I. Primary and primary-metasomatic mineralogy. Geochimica et Cosmochimica Acta 54, no. 2 (1990):
329-341.
Ionov, Dmitri A., Jochen Hoefs, K. Hans Wedepohl, and Uwe Wiechert. Content and isotopic composition
of sulphur in ultramafic xenoliths from central Asia. Earth and Planetary Science Letters 111, no. 2 (1992):
269-286.
Giuliani, A., D. Phillips, M. L. Fiorentini, M. A. Kendrick, R. Maas, B. A. Wing, J. D. Woodhead, T. H.
Bui, and V. S. Kamenetsky. "Mantle oddities: A sulphate fluid preserved in a MARID xenolith from the
Bultfontein kimberlite (Kimberley, South Africa)." Earth and Planetary Science Letters 376 (2013): 74-86.
58
Part III Projects 2016-17
51
Topic:
Crystal cargoes of Kilauean eruptions (L)
Supervisors:
Marie Edmonds and John Maclennan
Kilauea Volcano is among the most active volcanoes on Earth. Melts generated within the Hawaiian mantle
plume are erupted through the Kilauean edifice, perched on the southern flank of Mauna Loa, at a mean rate
of ~0.15 km3 per year. The current eruption, on the East Rift Zone, begun in 1983 and is the longest eruption
of Kilauea Volcano in the last 300 years. Lavas are basaltic and contain phenocrysts of olivine, with
plagioclase and augite in the groundmass. At first glance lavas and tephras erupted from Kilauea Volcano,
Hawaii, are uniform in their composition and in the types of crystals they carry. On closer inspection,
however, signs of disequilibrium and heterogeneity may be found, a result of their complex petrogenesis in
the mantle and crust. For example, the cores of olivine crystals erupted in Kilauea lavas are typically more
primitive (forsterite-rich) than expected based on the composition of the carrier liquid (melt). Melt inclusions
trapped in these crystals and the matrix glasses show a large range in trace element composition, thought to
be inherited from the mixing of melts generated in the mantle. Lavas are thought to be assembled in the crust
by batches of fresh magma entering magma reservoirs at various depths, fractionating, mixing with resident
magma, and perhaps entraining crystals from a mush formed by crystal settling.
This project will examine the compositions and sizes of olivine crystals erupted in tephras and lavas from
Kilauea Volcano. The study will address the following questions: (1) what is the relationship between crystal
size, morphology and composition at Kilauea Volcano? (2) do summit magmas differ from rift magmas? (3)
is there evidence for the more primitive magmas bypassing the shallow summit magma reservoir? (4) is
there evidence for magmas entraining cumulate-derived olivines in various staging areas in the crust?
Samples of 25 eruptions over the past 600 years of Kilauea’s history are available; of these, a small set of
samples will be selected for this study. Rocks will be cut and prepared for microanalysis. Backscattered
electron images of the samples (using the scanning electron microscope) will provide the basis for crystal
size distributions using image analysis software (ImageJ). Olivine composition will be measured using the
electron microprobe.
Sides IR, Edmonds M, Maclennan J, Swanson DA, Houghton BF. Eruption style at Kilauea Volcano in
Hawai/i linked to primary melt composition. Nature Geoscience. 2014 Jun 1;7(6):464-9.
Clague DA, Denlinger RP. Role of olivine cumulates in destabilizing the flanks of Hawaiian volcanoes.
Bulletin of Volcanology. 1994 Dec 1;56(6-7):425-34.
Mangan MT. Crystal size distribution systematics and the determination of magma storage times: the 1959
eruption of Kilauea volcano, Hawaii. Journal of Volcanology and Geothermal Research. 1990 Dec
30;44(3):295-302.
59
Part III Projects 2016-17
52
Topic:
Gas pipes associated with magmatic intrusions (F)
Supervisors:
Marie Edmonds and John Maclennan
Volcaniclastic breccia pipes are found associated with intrusions and magmatic provinces in many areas
around the world. They are commonly circular in plan, up to several hundred metres in diameter and made
up of coarse-grained angular breccia composed of a poorly-sorted mixture of igneous and sometimes
sedimentary country rocks, variably metamorphosed by heating. These pipes display variable degrees of ore
mineralisation. There are frequently crush zones and localised areas of sorting and rounding. They extend
from sub-volcanic depths (1-2 km), close to sills, to the palaeo-surface. They are of interest both in terms of
their mineralogy (they are often associated with economically important minerals) and for the implications
of their formation. They are generally interpreted to form due to gas overpressure, but the interpretation of
the origin of the gas varies from purely magmatic (e.g. in the case of the Bushveld; Boorman et al., 2003), to
being generated through contact metamorphism of volatile-bearing country rocks (Svensen et al., 2009); to
phreatic (involving groundwater). Despite the similar features of the pipes in various localities, there is no
consensus as to their origin and no present-day analogue.
In the Karoo Basin, South Africa, more than 1000 pipes, up to 150 metres in diameter, are rooted in the
contact aureoles of basaltic sills intruded into organic-rich shale (Aarnes et al., 2011). In the Siberian traps
they are magnetite-rich and up to a km across at the surface, filled with a glassy dolerite and sedimentary
fragments and abundant hydrothermal minerals, rooted in Cambrian evaporites adjacent to end-Permian
basaltic sills (Svensen et al., 2009). Volcaniclastic breccia pipes exist in the Bushveld layered intrusion
(Boorman et al., 2003) and in the early Jurassic Ferrar magmatic province in Antarctica. This project will
examine a series of volcaniclastic breccia pipes in the Cuillins, Skye, rooted in layered gabbros. Detailed
descriptions of these pipes have never been published and only the larger pipes are shown on the geological
maps. The student will map out the spatial distribution of the pipes and make a detailed description of them,
including their componentry and textural characteristics. Samples will be collected for bulk geochemical
analysis. Models of pipe formation driven by gas overpressure will be generated to explain the observations
and to understand the controls on their form and abundance.
Aarnes I, Svensen H, Polteau S, Planke S. Contact metamorphic devolatilization of shales in the Karoo
Basin, South Africa, and the effects of multiple sill intrusions. Chemical Geology. 2011 Feb 24;281(3):18194.
Boorman SL, McGuire JB, Boudreau AE, Kruger JF. Fluid overpressure in layered intrusions: formation of a
breccia pipe in the Eastern Bushveld Complex, Republic of South Africa. Mineralium Deposita. 2003 Apr
1;38(3):356-69.
Svensen H, Planke S, Polozov AG, Schmidbauer N, Corfu F, Podladchikov YY, Jamtveit B. Siberian gas
venting and the end-Permian environmental crisis. Earth and Planetary Science Letters. 2009 Jan
30;277(3):490-500.
60
Part III Projects 2016-17
53
Topic:
Chlorine cycling through subduction zones (R)
Supervisors:
Marie Edmonds and Helen Williams
Chlorine is an important and abundant volatile element in Earth: a primary constituent of volcanic gases and
the dominant dissolved anion in seawater. Of all chlorine in the Earth system however, 99% of it is stored in
the mantle. Over geological time, chlorine has been outgassed from mid-ocean ridges and during intra-plate
plume-related volcanism, and the mantle has been replenished to some degree by the subduction of chlorinebearing oceanic lithosphere at subduction zones. Circulation of seawater near to ridges causes extensive
alteration of oceanic crust and uppermost mantle. Serpentine, amphibole and smectite in altered oceanic
lithosphere are the primary sources of the chlorine entering subduction zones, wherein chlorine either
substitutes for hydroxyl in the mineral structure or is weakly bound. The behaviour of this chlorine during
subduction and slab devolatilisation is poorly known.
It is oberved that arc melts and volcanic gases are chlorine-rich (relative to MORB and OIB), suggesting that
at least a proportion of the chlorine subducted is returned to the crust and/or atmosphere. Evidence from the
Izu-Bonin arc suggests that chlorine is largely returned (outgassed) through volcanoes (Straub and Layne,
2003). Elsewhere, however, it is suggested that remnants of ancient subducted slabs created regions of
chlorine-rich mantle from which the Siberian Traps magmas were sourced (e.g. Sobolev et al,. 2011).
Studies of dehydrated serpentinites in the Alps retain significant amounts of chlorine, suggesting that
significant amounts of chlorine may be returned to the deep mantle during subduction (Kendrick et al.,
2011).
This project will harvest data on mafic arc melts from the literature and from online geochemical databases
from a range of subduction zones. The behaviour and source of the chlorine in the melts will be
characterised using statistical techniques to examine correlations with other elements e.g. LILE and other
volatiles (F, H2O). The chlorine data will be compared to the thermal structure of the slabs and where
possible, along-arc trends will be compared to subduction parameters (e.g. age of subducting crust, sediment
thickness). The overarching aim of the project is to cultivate a better understanding of the cycling of chlorine
at subduction zones.
Sobolev SV, Sobolev AV, Kuzmin DV, Krivolutskaya NA, Petrunin AG, Arndt NT, Radko VA, Vasiliev
YR. Linking mantle plumes, large igneous provinces and environmental catastrophes. Nature. 2011 Sep
15;477(7364):312-6.
Straub SM, Layne GD. The systematics of chlorine, fluorine, and water in Izu arc front volcanic rocks:
implications for volatile recycling in subduction zones. Geochimica et Cosmochimica Acta. 2003 Nov
1;67(21):4179-203.
Kendrick MA, Scambelluri M, Honda M, Phillips D. High abundances of noble gas and chlorine delivered to
the mantle by serpentinite subduction. Nature Geoscience. 2011 Nov 1;4(11):807-12.
61
Part III Projects 2016-17
54
Topic:
Testing sulfur isotopes and sulfur concentrations as indicators of marine influence in
Palaeozoic and Precambrian sedimentary rocks (L)
Supervisors:
Sasha Turchyn and Neil Davies
Aims
Sealevel incursions into the terrestrial realm result in changes in the sedimentology and geochemistry of the
deposited sedimentary rocks. Sulfur isotopes and sulfur concentrations can, in theory, be used as a
geochemical indicator of marine influence in the deposition of a given sedimentary rock because sulfate
concentrations are orders of magnitude higher in the ocean than in terrestrial environments. When samples
with sedimentological characteristics definitive of a terrestrial environment are lacking, geochemistry may
provide a powerful tool to explore marine influence on the sedimentary record.
A number of collected samples of Precambrian and Palaeozoic sediments are available for the student to
analyse. These come from a variety of successions for which sedimentological data indicates marine or
nonmarine deposition to varying degrees of certainty. Among them are problematic Neoproterozoic
sediments of the Cailleach Head Formation of Scotland and the Silurian Tumblagooda Sandstone of
Australia. These will be tested alongside a variety of other Precambrian to Permian samples, for which a
marine or nonmarine origin is more certain, based on sedimentological and palaeontological data. A
correlation between the sulfur geochemistry and the degree of marine or nonmarine influence is expected.
Methods:
There will be geochemical and isotopic work done in the Laboratory for Marine
Biogeochemistry including sulfur extractions and sulfur concentration measurements. Simple numerical
models for isotope fractionation in closed and open systems will be applied. Some method development
may occur, allowing the student to measure the sulfur concentrations spectrophotometrically prior to
precipitation and isotopic analysis. Funding for the project will be covered by existing grant funding.
Reading
Kraal et al., Iron monosulfide accumulation and pyrite formation in eutrophic estuarine sediments.
Geochimica et Cosmochimica Acta Vol. 122, pp 75-88. 2013.
Seal, R.R., Sulfur isotope Geochemistry of Sulfide Minerals, Reviews in Mineralogy and
geochemistry, Vol 61, pp 633-677 2006.
62
Part III Projects 2016-17
55
Topic:
Chemical weathering fluxes and processes in the Mekong River (L, F)
Supervisors:
Ed Tipper, Mike Bickle
Summary
Maintaining an equable climate over most of the Earth’s history implies a negative feedback which regulates
atmospheric CO2, the dominant greenhouse gas. Silicate weathering and carbonate formation (temperature
and precipitation dependent) and coupled burial of organic carbon have been cited as the major negative
feedbacks. Simultaneous increases in the Cenozoic marine records of strontium, osmium and lithium
isotopes, synchronous with major cooling of Earth’s climate, have been interpreted as increased CO2
consumption through the uplift and weathering of the Himalayan region. Because the surface carbon
reservoir is small relative to the weathering fluxes, atmospheric CO2 should have should have become
rapidly depleted with a runaway cooling effect on climate, unless the solid Earth release of CO2 also
increased. This paradox highlights the need to better understand the key processes. The fundamental
problem is that both the magnitude and control mechanisms of the global chemical weathering fluxes remain
poorly known. This project will to determine the magnitude and mechanisms of chemical weathering in the
Mekong River Basin, a continental area which contributes a major proportion of the global weathering flux.
The Mekong River with its headwaters on the Himalayan-Tibetan-Plateau is one of the largest in the world
and processes a major fraction of continental carbon.
Methods
The student will assist in the collection of river water/suspended sediment samples from the Mekong
catchment in Cambodia/Laos/Southern China in the summer vacation, as part of an ongoing research project
on the basin. The fieldwork will last for approximately two weeks. Upon return to Cambridge the water
samples will be analysed for cations and anions, and the sediments for major elements by XRF. The student
will conduct the analyses and interpret the data in the context of the samples collected last summer and an
archive of data in the literature.
Funding
Some of the funding for the fieldwork might be able to be provided from an existing grant, but if the student
is expected to contribute to this via travel grants. In addition to the cost of visa this would be a significant
benefit to cover visa, travel vaccinations as well as some travel and accommodation.
Reading
Moon et al, 2014, New estimates of silicate weathering rates and their uncertainties in global rivers, GCA,
134, 257-274.
West, AJ, 2012, Thickness of the chemical weathering zone and implications for erosional and climatic
drivers of weathering and for carbon-cycle feedbacks, Geology, 40, 811-814.
Li et al, 2014, Chemical weathering and CO2 consumption in the Lower Mekong River, Science of the Total
Environment, 472, 162-177.
63
Part III Projects 2016-17
56
Topic:
Investigating ice-sheet collapse at the penultimate deglaciation: dissecting
‘Heinrich event 11’ (L)
Supervisor:
Luke Skinner
Background and aims
This project focuses on the mechanisms and impacts of ice sheet collapse and sea level rise. Detailed
reconstructions of the evolution of ice-rafting and North Atlantic climate across the so-called ‘Heinrich
event 11’ (the last major ice-rafting event at the end of the pen-ultimate glaciation) will provide a window on
the pacing and punctuation of massive ice sheet loss (and therefore rapid sea level rise) at the end of a major
glaciation. Understanding how deglaciation is paced in response to slow isolation and CO 2 forcing (e.g.
gradual vs. punctuated ice loss) is required to shed light on the mechanisms that were responsible for
deglaciation. Although the last deglaciation has received a great deal of attention, and has raised some
interesting questions regarding the possibility of rapid ice-sheet instabilities in response to slow climate
forcing, relatively little attention has been paid to other examples of massive ice sheet loss, such as the penultimate deglaciation. This project will address this gap, and will shed much needed light on the processes
that led to the onset of the Last Interglacial; a warm period that has served as a possible (if also questionable)
indicator
of
climate
and
ice-sheet
response
to
future
temperature
rise.
Methods
This project will involve the generation of high-resolution (2cm or ~50-100yr interval) census counts of icerafted debris (IRD) deposited on the Iberian Margin using light reflecting microscopy, supported by very
high resolution (2mm interval) scanning X-ray fluorescence (XRF) measurements. The latter data already
exist, and are further supported by high-resolution stable isotope, pollen and planktonic/benthic foraminifer
trace-element data. The possibility will also exist to try to develop an approach for the estimation of IRD
mineralogy (hence sourcing) using X-diffraction. The new and existing data will be compared with other
records,
including
ice-core
and
speleothem
data,
from
around
the
world.
Logistics
The project is lab-based, and will primarily involve microscopy to generate new data. Existing data will also
be provided for interpretative purposes.
Finance
No
significant
costs
that
cannot
be
covered
by
existing
grants
are
envisaged.
Reading list
Cheng, H., Edwards, R.L., Broecker, W.S., Denton, G.H., Kong, X.G., Wang, Y.J., Zhang, R., Wang, X.F.,
2009. Ice Age Terminations. Science 326, 248-252.
Gregoire, L.J., Payne, A.J., Valdes, P.J., 2012. Deglacial rapid sea level rises caused by ice-sheet saddle
collapses. Nature 487, 219-U1506.
Siddall, M., Bard, E., Rohling, E.J., Hemleben, C., 2006. Sea-level reversal during Termination II. Geology
34, 817-820.
Skinner, L.C., Shackleton, N.J., 2006. Deconstructing Terminations I and II: revisiting the glacioeustatic
paradigm based on deep-water temperature estimates. Quat. Sci. Rev. 25, 3312-3321.
64
Part III Projects 2016-17
57
Topic:
The Southern Ocean and atmospheric CO2: constraining ‘solubility pump’
changes during the last glacial period (L)
Supervisors:
Luke Skinner and Sambuddha Misra
Background and aims
This project aims to reconstruct the first detailed record of deep-water temperature variability in the deep
Southern Ocean, focusing on the last deglaciation and Heinrich event 4, using benthic foraminifer Mg/Ca
ratios. The goal will be to assess in detail the link (and phasing) between changes in Southern Ocean (i.e.
Circumpolar Deep Water) deep-water temperature, atmospheric CO2, regional climate change and insolation
forcing. An auxiliary goal will be to assess the contribution of the ‘CO2 solubility pump’ (and its link to
abrupt inter-hemispheric climate change – the bipolar seesaw) to past atmospheric CO2 change, as compared
to more complex dynamical impacts of deep ocean temperature change (e.g. density stratification), or indeed
other ventilation or biological export productivity effects. Existing reconstructions of deep-water
oxygenation, radiocarbon ventilation and export productivity from the same sediment core and from other
locations will be available in order to assist interpretation of air-sea gas exchange, solubility- and soft-tissue
pump contributions to past CO2 variability.
Methods
This project will involve stable isotope and trace element geochemistry, and will focus primarily on the
Mg/Ca proxy for palaeothermometry. Infaunal benthic foraminifera will be picked (where these are not
already available) prior to being carefully cleaned in clean lab conditions and analysed by solution ICP-MS.
The possibility will also exist to compare results with others obtained in parallel by laser ablation (LA-) ICPMS.
Logistics
This project will primarily be lab based and will involve picking benthic foraminifer samples using a light
reflecting microscope (although many of the samples have already been picked), as well as clean lab
methods to purify the foraminifer calcite, dissolve it and then analyse it by ICP-MS. This project will be
time-consuming, primarily due to the need to perfect the methods prior to applying them to precious sample
material, and therefore an early start will be necessary. Existing auxiliary data will also be provided to aid
interpretation.
Finance
No
significant
costs
that
cannot
be
covered
by
existing
grants
are
envisaged.
Reading list
Roberts, J., Gottschalk, J., Skinner, L.C., Peck, V.L., Kender, S., Elderfield, H., Waelbroeck, C., Riveiros,
N.V., Hodell, D.A., 2016. Evolution of South Atlantic density and chemical stratification across the last
deglaciation. Proceedings of the National Academy of Sciences (avance publication online:
www.pnas.org/cgi/doi/10.1073/pnas.1511252113.
Martin, P., Archer, D., Lea, D.W., 2005. Role of deep-sea temperature in the carbon cycle during the last
glacial cycle. Paleoceanography 20, 1-10.
Sigman, D.M., Hain, M.P., Haug, G.H., 2010. The polar ocean and glacial cycles in atmospheric CO2.
Nature 466, 47-55.
Skinner, L.C., Shackleton, N.J., Elderfield, H., 2003. Millennial-scale variability of deep-water temperature
and d18Odw indicating deep-water source variations in the Northeast Atlantic, 0-34 cal. ka BP. Geochem.
Geophys. Geosys. 4, 1-17.
65
Part III Projects 2016-17
58
Topic:
Developing proxies for deep ocean oxygenation: a powerful metric of past marine
carbon cycling (L)
Supervisors:
Luke Skinner, Sambuddha Misra, David Hodell
Background and aims:
The distribution of dissolved oxygen in the ocean interior is intimately connected to the biological cycling of
organic carbon and atmosphere-ocean gas exchange. As such it has a direct bearing on the marine carbon
cycle, including in particular the balance of pre-formed versus remineralised nutrients in the ocean interior,
which is expected to exert a primary control on atmospheric CO2 on millennial- and glacial-interglacial
timescales (Ito and Follows, 2005; Sigman et al., 2010). If new insights into the past oxygenation of the
ocean interior can be obtained, our understanding of the ocean’s role in past atmospheric CO2 variability (in
particular via the action of the ocean’s ‘soft-tissue carbon pump’) may be greatly improved. This project
will make use of a set of newly recovered multi-core and gravity/piston core sediments and pore-water
samples from the Iberian Margin (Northeast Atlantic) to develop novel proxies for deep-water oxygenation,
including in particular bulk sediment and dispersed phase redox chemistry, and benthic foraminifer stable
isotope ratios.
Logistics
This project will primarily involve the analysis of foraminifer samples for stable isotope and trace-element
composition. Both foraminifer chemistry and the chemistry of their authigenic coatings will be targeted,
using multi-core samples of the upper ~30cm of marine sediments. Results will be compared with deepwater and pore-water analyses (pH and oxygenation) that have been obtained already. The project will
consist primarily of microscope and laboratory (clean-lab, mass spectrometer) work.
Reading
Boiteau, R., Greaves, M., Elderfield, H., 2012. Authigenic uranium in foraminiferal coatings: A proxy for
ocean redox chemistry. Paleoceanography 27.
Ito, T., and Follows, M.J., 2005, Preformed phosphate, soft tissue pump and atmospheric CO2: Journal of
Marine Research, v. 63, p. 813-839.
McManus, J., Berelson, W., Klinkhammer, G., Hammond, D.E., and Holm, C., 2005, Authigenic uranium:
relationship to oxygen penetration depth and organic carbon rain: Geochimica et Cosmochimica Acta, v. 69,
p. 95-108.
Rosenthal, Y., Boyle, E., Labeyrie, L., and Oppo, D.W., 1995, Glacial enrichments of authigenic Cd and U
in Sub-Antarctic sediments - a climatic control on the elements oceanic budget: Paleoceanography, v. 10, p.
395-413.
66
Part III Projects 2016-17
59
Topic:
The Atlantic Ocean in overdrive: did abrupt changes in ocean ventilation
drive centennial atmospheric CO2 jumps over the last 42,000 years? (L)
Supervisor:
Luke Skinner
Background and aims
New high-resolution records of atmospheric variability have revealed extremely abrupt jumps in CO 2 that
appear to be in phase with Northern Hemisphere abrupt climate changes (see Reading list). This challenges
the previously accepted purely ‘Antarctic temperature association’ of millennial CO 2 variability during the
late Pleistocene, and raises the question of whether these large and rapid jumps in CO2 had their origin in
abrupt marine processes (e.g. ocean circulation/ventilation) or terrestrial processes (e.g. permafrost melting).
This project aims specifically to assess evidence for an Atlantic Ocean circulation contribution to these rapid
jumps in CO2 through reference to marine and atmospheric radiocarbon evidence. The aim will be to
produce new high-resolution marine radiocarbon ventilation records from the deep Atlantic in order to seek
out (or indeed prove the absence of) rapid changes in deep ocean ventilation that coincide with the observed
sub-millennial atmospheric CO2 jumps, e.g. at 16.3, 14.8 and 11.7 ka BP.
Methods
This project will make use of marine stable isotope and radiocarbon measurements, and will involve the
picking of benthic and planktonic foraminifera via light reflecting microscropy, followed by careful
cleaning, hydrolysis and graphitisation (reduction of CO2 to graphite), prior to radiocarbon dating by
accelerator mass spectrometry (AMS) at the Queen’s University Belfast 14Chrono Centre. New results will
be compared with other existing high-resolution atmospheric (ice core) and marine records, as well as
numerical modelling results.
Logistics
This project will primarily be lab based and will involve some sediment processing (sieving), picking of
benthic and planktonic foraminifer samples using a light-reflecting microscope, as well as sample cleaning
and graphitisation. The project will benefit from an early start (e.g. September), in order to process and pick
samples and to learn the sample preparation and graphitisation methods before applying them to sample
material, but this is not necessary.
Reading list
Ahn, J., Brook, E.J., Schmittner, A., Kreutz, K., 2012. Abrupt change in atmospheric CO2 during the last ice
age. Geophys. Res. Lett. 39.
Marcott, S.A., Bauska, T.K., Buizert, C., Steig, E.J., Rosen, J.L., Cuffey, K.M., Fudge, T.J., Severinghaus,
J.P., Ahn, J., Kalk, M.L., McConnell, J.R., Sowers, T., Taylor, K.C., White, J.W.C., Brook, E.J., 2014.
Centennial-scale changes in the global carbon cycle during the last deglaciation. Nature 514, 616.
Skinner, L., Waelbroeck, C., Scrivner, A., Fallon, S., 2014. Radiocarbon evidence for alternating northern
and southern sources of ventilation of the deep Atlantic carbon pool during the last deglaciation. Proceedings
of the National Academy of Sciences 111, 5480–5484.
67
Part III Projects 2016-17
60
Topic:
Reconstructing glacial Indian summer monsoon variability at sub-annual to
sub-decadal scale in a stalagmite from NE India using LA-ICPMS
Supervisors:
Sebastian Breitenbach, Aleksey Sadekov and Luke Skinner
Background and aims
Hydrological changes associated with the Asian summer monsoon directly affect up to 30% of the world’s
population. There is an urgent need to assess the physical mechanisms behind those changes, delineate
anthropogenic from natural forcing factors and to improve forecasting strategies. Paleoclimate archives
allow deep insights into amplitude and frequency of natural variations in monsoon strength. Among the best
terrestrial paleoclimate archives are stalagmites, due to their ubiquitous distribution, datability, robustness
against diagenesis and the rich collection of environmentally sensitive proxies that can be extracted
(Fairchild & Baker, 2012). A well-dated stalagmite from NE India reveals the sensitivity of the Indian
summer monsoon (ISM) to Dansgaard/Oeschger cycles and Heinrich events. Recent studies from the region
suggest strong modern teleconnections between the ISM and ENSO, as well as the PDO (2). It is unclear
however if these links remained intact under glacial climate conditions, or if full glacial and interstadial
conditions were characterized by divergent forcings. Equally unknown are the rate of change from dry
Heinrich event phases to full D/O interstadial conditions. Finally, quantification of changes in effective
infiltration and/or seasonality remains elusive albeit of major importance for assessing vulnerability of
agricultural societies to climate change.
The proposed project aims to develop time series of element concentrations and ratios at sub-annual to subdecadal temporal resolution through a transition from Heinrich event 4 into D/O interstadial 8. The aim is to
reconstruct changes in effective infiltration and the governing forcing factors that drove those changes.
Statistical treatment (with focus on spectral analysis) of the obtained element profiles is central to the
reconstruction of the (likely non-stationary) impact of ENSO and PDO on the monsoonal system. A
stalagmite section will be analysed using the laser ablation facility of the Godwin Laboratory for
Palaeoclimate Research. Statistical treatment of the collected data will be pursued in Matlab and/or
Analyseries, depending on suitability.
Methods
Over the duration of the project, the student will learn basic operational skills of laser-ablation ICP massspectrometry in application to environmental geochemistry. He/She will learn to construct age models using
the COPRA routine (Breitenbach et al., 2012), and general treatment of stalagmite-based paleoclimate
reconstructions. The student will get training in statistical methods, including spectral analysis and
recurrence network tools (Rehfield et al., 2013).
Logistics
This project is lab and office based. Sample analyses will involve a) literature review (1 week), b) sample
preparation and analysis using the inhouse LA-ICP-MS facility (1 week), c) Statistical analysis (~4 weeks).
It is desirable, but not strictly necessary, that the student has lab experience. For timely completion of the
project it is desirable that the student starts early and has basic experience in statistical time series analysis.
Reading
Fairchild & Baker, Speleothem Science, Wiley & Sons, 2012
Myers et al. (2015) Northeast Indian stalagmite records Pacific decadal climate change: implications for
moisture transport and drought in India. Geophysical Research Letters 42
Breitenbach S.F.M. et al. (2012) COnstructing Proxy Records from Age models (COPRA). Climate of the
Past 8, 1765-1779
Rehfeld et al. (2013) Late Holocene Asian Summer Monsoon dynamics from small but complex networks of
paleoclimate data. Climate Dynamics 41, 3-19
68
Part III Projects 2016-17
61
Topic:
Evaluating environmental changes in (sub-)tropical stalagmites at annual to
sub-decadal scale using tandem 14C and U-series dating methods (L)
Supervisors:
Sebastian Breitenbach, Aleksey Sadekov and Luke Skinner
Background and aims
Seasonal rainfall associated with the Asian summer monsoon affects up to 30% of the world’s population.
Quantitative reconstructions of variations in monsoonal precipitation are urgently needed to assess potential
future development of rainfall variability in Asia and the vulnerability of agricultural societies. Anomalous
radiocarbon fluctuations archived in stalagmites (i.e. with respect to those expected due to atmospheric
radiocarbon activity changes, resulting from carbon cycle and/or 14C-production changes) may serve as a
sensitive monitor of effective moisture changes in the cave system (Fairchild & Baker, 2012; Fohlmeister et
al., 2011). In concert with stable isotope data, radiocarbon changes recorded in stalagmites may therefore
help delineate local moisture balance and regional monsoon dynamics. Fast growing stalagmites offer the
potential to gain insights into the processes that govern high-frequency changes in 14C flux into caves under
various climate conditions (e.g. full glacial, interstadial, or Holocene). In conjunction with high-precision Useries dating 14C analyses might thus contribute to our understanding of the geochemical and physical
mechanisms behind observed changes. This may open up new avenues towards quantitative rainfall
reconstructions.
The proposed project aims to develop high-resolution and precisely U-series dated time series of 14C changes
in Asian stalagmites with the goal to reach annual to sub-decadal temporal resolution. U-series dating will be
performed using frontier laser ablation techniques developed at the University of Cambridge. 14C analyses
will be conducted in collaboration with partners at the AMS facility at ETH Zurich. Obtained U-series dates
and 14C data will be analysed in conjunction with element composition and stable isotope data. The aim is to
understand the processes governing observed proxy changes and to develop transfer functions for
quantitative reconstructions of past rainfall changes.
Methods
Over the duration of the project, the student will learn operational skills of laser-ablation ICP massspectrometry based U-series dating. He/She will construct age models using the COPRA routine
(Breitenbach et al., 2012), and (together with colleagues at ETH Zurich) develop high-end 14C time series
and potentially monsoon rainfall reconstructions. Statistical reanalysis of the multi-proxy dataset will be
crucial, including PCA. 14C analyses will be conducted at ETH Zurich and the student will interact with the
Swiss partners.
Logistics
This project is lab and office based. Sample analyses will involve a) literature review (1 week), b) sample
preparation and analysis using the inhouse LA-ICP-MS facility (2 weeks), c) Statistical analysis (~3 weeks).
It is desirable that the student has lab experience. For timely completion of the project it is desirable that the
student starts early and has basic experience in statistical time series analysis.
Reading
Fairchild & Baker, Speleothem Science, Wiley & Sons, 2012
Fohlmeister et al. (2011) Radiocarbon 53, 99-115
Breitenbach S.F.M. et al. (2012) COnstructing Proxy Records from Age models (COPRA). Climate of the
Past 8, 1765-1779
69
Part III Projects 2016-17
62
Title:
The morphology of impact craters (L)
Supervisor:
Jerome Neufeld (BPI, Earth Sciences, DAMTP), Stuart Dalziel (DAMTP)
Impact cratering is an important geological process that templates the surface of planetary bodies. The
extent of cratering provides a key method of remotely estimating the age of planetary surfaces, and has been
used to estimate the time since tectonics were active on, for example, Mars. The morphology of impact
caters varies between small “simple” craters with roughly parabolic interior profiles, to larger “complex”
craters with single or multiple central peaks, flat inner floors, and terraced rims (Melosh & Ivanov, 1999).
More recently the presence of lobate deposits on complex Martian craters at high latitudes has been
associated with the presence of a glacial substrate (Weiss & Head, 2013).
This project will explore the wide range of observed morphological features through high-speed imaging of
the impact of a yield-stress fluid. Yield-stress fluids, such as carbopol, act as a solid until subject to a
sufficient stress after which they flow as a fluid. In trial experiments, the impact of a droplet of such a fluid
relaxes to a series of non-trivial shapes for different impact velocities and sizes, largely mimicking the wide
range of phenomena observed in planetary craters. The student will conduct a suite of systematic
experiments using a high-speed camera to track the motion of tracer particles in carbopol in order to image
deformation during impact and relaxation to the final state. Profiles of the resulting laboratory craters will
be imaged using laser profilometry. These results will be used to understand the morphology and genesis of
planetary impact craters.
Experiments will be conducted in the DAMTP fluid dynamics laboratory, and training will be given on
working with yield-stress fluids, high-speed cameras, laser profilometry and image processing.
Melosh, H.J., Ivanov, B.A. (1999). Impact crater collapse. Ann. Rev. Earth Planet. Sci., 27, 385–415.
Weiss, D.K., Head, J.W. (2013). Formation of double-layered ejecta craters on Mars: A glacial substrate
model. Geophys. Res. Lett., 40(15), 3819–3824.
70
Part III Projects 2016-17
63
Title:
Fingered spreading of the Icelandic plume (L)
Supervisor:
Jerome Neufeld (BPI, Earth Sciences, DAMTP)
The formation of a series of v-shaped ridges of thick oceanic crust intersecting the North Atlantic mid-ocean
ridge are thought to record pulses in the upwelling of the Icelandic plume (Parnell-Turner et al., 2014). The
hot plume material upwells underneath Iceland and spreads laterally in the low-viscosity of the upper
aesthenospheric mantle. Previous models have used the flow in this low-viscosity channel to infer the
advection of the relatively hot pulses of plume material, and thus calculate the record of transient uplift
observed in the North Atlantic (Rudge et al., 2008).
Previous models have focused on the axisymmetric spreading of the Icelandic plume in the low-viscosity
aesthenospheric channel. However, seismic studies suggest a much more complex pattern, with long fingers
of hot material extending to Scotland, for example. This project will examine the potential for fingering of
hot, and therefore low-viscosity, plume material through analogue laboratory experiments. To model the
plume material, a dyed mixture of water and glycerine will be injected in pulses into a channel of pure
glycerine overlain by a thin elastic sheet. Images of the spreading dye will be recorded using a camera and
analysed to detect localised fingers of dyed plume material. The upper surface of the elastic sheet will be
tracked using techniques developed previously for use in a similar system (Lister et al., 2013), enabling an
experimental measurement of the uplift associated with the transit of the “hot” plume material. The result of
the experiments will be a regime diagram delineating regions of axisymmetric verses fingered spreading,
which will be used to interpret the observed behaviour of uplift in the North Atlantic.
Experiments will be conducted in the BPI fluid dynamics laboratory, and training will be given on working
with viscous fluids, digital cameras, and image processing.
Lister, J.R., Peng, G.G., Neufeld, J.A. (2013). Viscous control of peeling an elastic sheet by bending and
pulling. Phys. Rev. Lett., 111, 1–5.
Parnell-Turner, R., White, N., Henstock, T., Murton, B., Maclennan, J., Jones, S.M. (2014). A continuous
55-million-year record of transient mantle plume activity beneath Iceland. Nature Geosci. 7, 914-919.
Rickers, F., Fichtner, A., Trampert, J. (2013). The Iceland–Jan Mayen plume system and its impact on
mantle dynamics in the North Atlantic region: Evidence from full-waveform inversion. Earth Planet. Sci.
Lett. 367, 39-51.
Rudge, J.F., Shaw Champion, M.E., White, N., McKenzie, D., Lovell, B. (2008). A plume model of transient
diachronous uplift at the Earth's surface. Earth Planet. Sci. Lett., 267(1-2), 146–160.
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Topic:
An assessment of early diagenetic influences on the chemistry of infaunal versus
epifaunal benthic foraminifera. (L)
Supervisors:
Mervyn Greaves, Aleksey Sadekov, David Hodell.
Aims
The ability to infer past climate change is inextricably linked to proxy development and empirical calibration
of proxies with modern observations. However, there is a lack of studies examining in detail the
relationships of geochemical proxies in benthic foraminifera to the chemistry of the sediments and
associated pore waters. For example, accurate calibrations of benthic foraminiferal ‘Mg/Ca thermometry’
require core tops that span a range of hydrographic conditions along a local depth transect and, in order to
obtain deep-water temperature reconstructions across glacial and interglacial time periods, infaunal as well
as epifaunal benthic foraminifera must be used. There are few accurate calibrations of benthic foraminiferal
‘Mg/Ca thermometry’ and the ‘carbonate ion effect’ on foraminiferal Mg/Ca remains to be quantified.
Mg/Ca ratios of epifaunal benthic foraminifera are known to be affected by carbonate saturation whereas this
effect has been shown to be reduced, or possibly absent, for infaunal species. It is important to establish
whether the geochemical signature of a given foraminifera species reflects a bottom water signal, a porewater signal or some combination of these.
Methods
This project will involve stable isotope and trace element geochemistry. Infaunal and epifaunal benthic
foraminifera will be picked, including from samples previously stained to identify recently living
foraminifera. Stable oxygen and carbon isotopes will be measured on the dominant epifaunal and infaunal
benthic foraminifera, in parallel with trace-element ratios (in particular Mg/Ca and B/Ca) which will be
determined on individual foraminifera tests by laser ablation (LA-) ICP-MS. Results will be compared to
the carbonate and trace element chemistry of bottom water and porewaters extracted from the same cores.
Logistics
This project is entirely lab based, using samples collected from the Iberian Margin. Some existing porewater
and foraminifera trace element data are available which will be supplemented by further analyses as
required.
Finances
Instrument running costs and the cost of chemicals for the analyses will be covered by existing research
projects.
Reading
H. Elderfield, J. Yu, P. Anand, T. Kiefer, B. Nyland. Calibrations for benthic foraminiferal Mg/Ca
paleothermometry and the carbonate ion hypothesis. Earth Planet. Sci. Lett. 250, 633 (2006).
J. Yu, W. S. Broecker, Comment on “Deep-Sea Temperature and Ice Volume Changes Across the PliocenePleistocene Climate Transitions” Science 328, 1480 (2010).
S. Sosdian, Y. Rosenthal. Response to Comment on “Deep-Sea Temperature and Ice Volume Changes
Across the Pliocene-Pleistocene Climate Transitions” Science 328, 1480 (2010).
H. Elderfield, M. Greaves, S. Barker, I.R. Hall, A. Tripati, P. Ferretti, S. Crowhurst, L. Booth, C. Daunt. A
18
O for the Southern Ocean over the past 440 kyr based
on Mg/Ca of benthic foraminiferal Uvigerina spp. Quat. Sci. Rev. 29, 160 (2010).
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Part III Projects 2016-17
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Topic:
Archosaurian tracks from the Connecticut Valley: characterising a previously
unknown collection of tracks at the Sedgwick Museum (L/M)
Supervisor:
David Norman
Aims
From about 1835 onward the Revd Edward Hitchcock (based at Amherst College, Massachusetts) collected
and described many footprints that had been discovered in the Connecticut Valley area. He regarded very
many of them as the prints left behind by large bird-like creatures with either thick or slender toes
(‘pachydactylous’ or ‘leptodactylous’). His work culminated in comprehensive accounts of these prints
published in 1858 and 1865. In fact he was documenting the first discoveries of dinosaur tracks and traces
(as well as several other animals). While the majority of his collections still reside in Amherst (at the Pratt
Museum) it is clear that specimens were sent to people (such as Adam Sedgwick) to supplement their own
collections, or perhaps as part of specimen exchanges. These specimens have, hitherto, been overlooked and
unappreciated. This project provides an opportunity to describe and document these important specimens
and apply modern approaches to these specimens in order to better understand their significance, and the
types of animal that they represent.




To accurately record and document the Hitchcock specimens.
To photograph, digitally scan and, where appropriate, provide interpretative diagrams of the original
specimens so that they can be described accurately.
Study the morphology of the tracks and matrix to determine whether they are surface tracks or
underprints.
To investigate the morphology of the prints to determine: (i) foot structure, (ii) infer the pose of the foot
and locomotor gait of each print-maker. (iii) the potential identity of the print-makers.
Methods



Digital surface scanning to image print details accurately
Incident light photography and interpretative drawings of images
Comparative studies: using published accounts of trackways, comparison with the foot anatomy of
contemporaneous fossil taxa.
Logistics
Museum/lab – based. Specimens are on display in the museum, and some can be removed for
photography/study/preparation in the Brighton Building (Conservation/Preparation Lab)
Similar prints may be present in some other large UK museums, and these should be visited and also
studied as part of the project.
Finance
~£100 – to cover travel, scanning and printing costs
Reading
Steinbock, R.E. (1989). Ichnology of the Connecticut Valley: a vignette of American science in the early
nineteenth century. Pp. 27-32 [in] Dinosaur tracks and traces [eds Lockley & Gillette]. Cambridge
University Press. [And references therein.]
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Topic:
Micro-CT scanning of a fish skull (preserved in the round) to investigate
its detailed internal anatomy, function and systematic position (L/M)
Supervisor:
David Norman
Aims
A diverse collection of fish skulls are housed in the collections of the Sedgwick Museum. The original
specimens were found as nodules, which appear to preserve the three-dimensional structure of the skull more
or less intact. The delicacy of bones in fish skulls means that mechanical preparatory techniques are not only
very time-consuming, but very risky when applied to skulls of this type. As a result this rich collection of
skulls remains virtually unstudied (except in a very superficial sense).
CT scanning technology enables details of the internal structure of skulls such as these to be imaged noninvasively. This project will allow a skull to be selected, scanned and then imaged and segmented so that a
3D representation of the anatomy can be presented. Details of this anatomy will enable to the skull to be
characterised and compared with other, related, taxa. Skull structure will enable the functional mechanics of
the skull to be investigated so that a comprehensive reconstruction of the anatomy and biology of the
original fish can be made.
Methods
MicroCT scanning (training and scanning time), image manipulation and segmentation (training).
Conventional photography. Simple interpretative drawings based upon the specimen directly or from
images. Anatomical research time (comparative and basic). Some functional analysis of structures.
Systematic techniques (where necessary).
Logistics
Scanner is located in Cambridge. Material is based in the Sedgwick Museum. CT scanning may best be done
during the summer vac (by negotiation).
Finance
£200 – to cover scanner time and training in use of scanner and software under supervision.
Reading
Back issues of Journal of Vertebrate Paleontology (fDN has these, if necessary)
Basic texts for anatomy/function:
Alexander, RM (1967) Functional design in fishes. Hutchinson
Romer AS & Parson TM. The vertebrate body. Chicago University Press.
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Part III Projects 2016-17
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Topic:
MicroCT scanning of an intact skull of the Neogene crocodile (“Crocodilus
hantonensis”) in order to investigate the details of its internal anatomy, function and
relationships (L/M)
Supervisor:
David Norman
Aims
Crocodiles (Archosauria: Diapsida) have a reasonably good fossil record because many of them lived in or
around depocentres. Some very well-preserved crocodilian remains are preserved in the Sedgwick
Collections. These specimens are exposed by mechanical preparation externally but the details of their
internal structure is unknown (and obscured by matrix). This specimen will benefit from MicroCT scanning
and manipulation and segmentation of the resultant scans to produce high quality images of the internal
cranial structures.
Comparison of this newly described structure with that in other known crocodilians, as well as information
derived from the literature, will be necessary in order to deduce its biology and way of life, as well as
analysing skull mechanics/function, systematics and phylogenetics.
Ultimately the questions are: how much can we discover about its detailed anatomy? what sort of crocodile
was this? and, what was it doing in Hampshire during the Neogene?
Methods
CT scanning training. Software training to construct anatomical 3D images from the original scanned files.
Traditional photography, some interpretative drawing (where necessary), some descriptive anatomy,
systematic methods, functional analysis leading to deductions relating to the likely way of life.
Logistics
Lab-based. The student will collect his/her own data and analyse it using comparative and systematic
methods. Training in scanning and use of software, as well as descriptive methods and systematic methods.
Finance
~£200 to cover scanning costs and photography
Reading list
Start here, for speed:
http://en.wikipedia.org/wiki/Crocodile
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Part III Projects 2016-17
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Topic:
state? (L and C)
Interacting single-domain clusters: a good analogue of the pseudo-single domain (PSD)
Advisors:
Richard Harrison, Nono Lascu, Josh Einsle
Aims
Current paleomagnetic methods are almost entirely reliant on non-interacting single-domain theory, despite the
fact that the majority of stable remanence in rocks is carried by pseudo-single domain grains. Single-domain
theory is attractive because it is simple enough to be of practical use yet captures the essential physics of the
remanence acquisition process. A key question, therefore, is what is the simplest modification that can be made
to single-domain theory that a) captures the physics of the PSD state and b) remains simple enough to be of
practical use in paleomagnetism? In this project we will use a combination of rock magnetic and paleomagnetic
data, 3D nanoscale tomography and computer modelling to explore whether small interacting clusters of singledomain particles provide a good physical analogue of the PSD state, thereby providing a route to a practical
theory for the acquisition of remanence by PSD grains. It is known that such clusters display high-field
hysteresis properties that are a close match to those of true PSD grains. However, whether this analogy also
applies to the low-field remanence acquisition properties is unknown. New and existing rock magnetic data will
be analysed to characterise the remanence properties of samples that have well-defined magnetic grain sizes
lying exclusively in the PSD size range (0.1-5 µm). Computer modelling of the field- and temperature-response
of interacting clusters of single-domain particles will be performed using a kinetic Monte Carlo algorithm, and
tested against the experimental data. A true test of the analogy will be made by performing full micromagnetic
simulations based on nanoscale tomographic reconstructions of individual PSD particles.
Methods
Experimentally we will focus on samples of fire obsidian that contain magnetite grains exclusively in the PSD
state. First-order reversal curve (FORC) diagrams, alternating-field and thermal demagnetisation data sets will
be used to characterise the remanence properties. Electron microscopy will be used to characterise the particles
in the samples, and focussed ion beam nanotomography (FIB-nt) will be used to obtain high resolution
reconstructions of the 3-dimensional morphology of a range of PSD grains. The reconstructions will be
converted to finite-element meshes and used to perform full micromagnetic simulations. Finally, computer
simulations of clusters of interacting single-domain particles will be performed, and compared to both the
experimental and micromagnetic results.
Logistics
The Part II C4 Core Mineralogy course is a pre-requisite for this project. The project will involve about 25%
experimental measurements, 25% data processing, and 50% computer simulations. No programming experience
is required, although there will be opportunity to go in this direction depending on the interests of the student.
Resources
Samples, equipment and partial data are already available. The necessary software has been written by the
advisor, although the student will be encouraged to make improvements where appropriate. Full training will be
given in performing experiments and analysis.
Reading
Harrison, R.J., Lascu, I., 2014. FORCulator: A micromagnetic tool for simulating first-order reversal curve
diagrams. Geochemistry Geophys. Geosystems 15, 4671–4691.
Joshua F. Einsle, Richard J. Harrison, Wyn Williams, Patrick Conway, Takeshi Kasama, Roger R. Fu, Benjamin
P. Weiss, Paul Midgley (2016) Multi-scale 3D characterisation of iron particles in dusty olivine: implications
for paleomagnetism of chondritic meteorites, American Mineralogist, Submitted (available from Richard
Harrison on request).
Shcherbakov, V.P., Lamash, B.E., Sycheva, N.K., 1995. Monte-Carlo modelling of thermoremanence
acquisition in interacting single-domain grains. Phys. Earth Planet. Inter. 87, 197–211.
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Part III Projects 2016-17
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Topic:
Magnetism of ocean sediments: quantitative unmixing of magnetic signals during
Heinrich events
Advisors:
Richard Harrison, Nono Lascu, Dave Hodell
Aims
Magnetic proxies are a powerful way to track environmental, biological and climatic changes in terrestrial,
lacustrine and marine sediments. The magnetic properties of sediments are highly sensitive to variations in
the concentration, grain size, morphology, chemical composition, structure and microstructure of the
magnetic minerals within them. Variations in climatic and environmental conditions on both global and local
scales produce subtle changes in the magnetic mineralogy of sediments – changes that can be detected
rapidly and non-destructively using high-sensitivity rock magnetometers. A fundamental requirement of
magnetoclimatological studies is the quantification of a sediment’s magnetic mineralogy, i.e. the
concentration of the different mineral phases present and the distribution of particle sizes for each phase. The
magnetic state of a particle is highly sensitive to its size and shape, changing from superparamagnetic (SP)
to single-domain (SD) to pseudo-single-domain (PSD) and finally to multi-domain (MD) as the particle size
increases from a few tens of nanometres to several tens of microns. Hence quantifying the proportions of
different magnetic states present in a sediment is fundamental to determining the size of the magnetic
particles. This project will apply a newly developed method of quantitative unmixing of complex magnetic
mixtures using principle component analysis (PCA) of first-order-reversal-curve (FORC) diagrams – an
advanced method of measuring the magnetic hysteresis properties of a sediment.
Methods
There are two parts to the project. The first part will involve high-resolution subsampling of sediment cores,
followed by detailed measurement of their magnetic properties using FORC analysis on our Vibrating
Sample Magnetometer (VSM). The data will be used to create a 3D stack of FORC measurements depicting
the changes in magnetic properties throughout the core. The second part will involve the application of PCA
to separate the varying contributions to the magnetic ensemble from biogenic SD magnetite, detrital PSD
and MD components. The results will be applied to study the occurrence and provenance of ice-rafted
detritus (IRD) in the North Atlantic during the last glacial period, including the high-resolution
characterisation of Heinrich event H1, which shows a double pulse of coarse IRD. Preliminary data show
large and systematic changes in the magnetic properties associated with the changes in grain size at the
peaks and troughs of the double Heinrich event. This project will provide a much higher spatial resolution
record, enabling the PCA method to be applied to obtain the first quantitative analysis of the magnetic
signature of such events.
Logistics
The Part II C4 Core Mineralogy course is a pre-requisite for this project. The project will involve about 50%
experimental measurements, 50% data processing and analysis. No programming experience is required,
although there will be opportunity to go in this direction depending on the interests of the student.
Resources
Samples, equipment and partial data are already available. The necessary software has been written by the
advisor, although the student will be encouraged to make improvements where appropriate. Full training will
be given in performing experiments and analysis.
Reading
Lascu, I., Harrison, R.J., Li, Y., Muraszko, J.R., Channell, J.E.T., Piotrowski, A.M., Hodell, D.A., 2015.
Magnetic unmixing of first-order reversal curve diagrams using principal component analysis.
Geochemistry, Geophys. Geosystems 16, 2900–2915.
Channell, J.E.T., Hodell, D. a., 2013. Magnetic signatures of Heinrich-like detrital layers in the Quaternary
of the North Atlantic. Earth Planet. Sci. Lett. 369-370, 260–270.
Roberts, A.P., Heslop, D., Zhao, X., Pike, C.R., 2014. Understanding fine magnetic particle systems through
use of first-order reversal curve diagrams. Rev. Geophys. 52, 557–602.
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Part III Projects 2016-17
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Topic:
Dynamics of Magma Degassing (L)
Supervisors:
Andy Woods and Marie Edmonds
The formation of anhydrous crystals on magma cooling enriches the residual melt in volatiles
and can lead to gas exsolution. The internal mixing dynamics of volatile rich magma, and the interaction
with an overlying, less dense but more viscous body of melt have been explored experimentally
in the case of low crystal content.
As the volatile content increases, the density falls, and eventually magma mixing and overturn can ensue,
provided the volatiles cannot separate from the melt through buoyant ascent. With buoyant ascent of the
bubbles, the volatiles form a foam at the magma-magma interface which then generates buoyant, bubble-rich
parcels of lower layer melt rising through the upper layer.
With larger crystal fractions in the lower, volatile-rich melt, the dynamics may be rather different, owing to
the transition to a jammed crystal-liquid state when there is sufficient crystal content in the melt. The effect
of gradual bubble exsolution in such a crystal laden system is less well studied, especially the details of the
mixing processes between this lower layer and the upper magma. The aim of the project is to develop a suite
of new experiments in the BPI laboratories building on the experimental system developed by M Ptacek
during his Part III project.
The study will focus on the mixing behaviour of the magmas, and in particular will assess the controls on
three end-member regimes including (i) full-scale overturn ; (ii) slow injection of inclusions of the lower
melt into the upper layer and (iii) volatile separation and degassing, with little magma mixing.
The project will also involve identifying the relation of these regimes with the different behaviour of
volcanic systems, especially the eruption of Soufriere Hills volcano, Montserrat.
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Part III Projects 2016-17
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Topic:
Magmatic plumbing under Skaftafell, Iceland
Supervisor:
John Maclennan, Simon Matthews, Oli Shorttle
Aims
The isotope geochemistry of young volcanic rocks from southern Iceland indicates that a distinctive mantle
source composition is present in the region close to the Öræfajökull volcanic system. Basaltic rocks from the
Skaftafell area share this isotopic flavour and also contain plentiful macrocrysts of olivine, clinopyroxene
and plagioclase. Relatively little is known about the petrology of these rocks, nor how it reflects the depth
distribution of magma chambers under the Icelandic flank zones. The aim of the project is to constrain the
pressure and temperature of crystallisation under Skaftafell, and to examine the timescales of magmatic
processes in this system. By comparison with other well-studied regions of Iceland, the student will start to
explore the relationship between mantle source composition, mantle melt fluxes and sub-volcanic magmatic
plumbing.
Methods
A suite of porphyritic basalt samples from the Skaftafell region has already been collected. The student will
prepare these samples for petrographic and microanalytical study. Textural information will be obtained
from thick sections, including measurement of crystal size distributions and plagioclase aspect ratios.
Microanalysis of the crystal compositions will be used as input to thermos-barometric parameterisations.
The distribution of crystal core compositions will be used explore mush-zone processes, and compositional
profiles across individual crystals will be modelled to constrain timescales between mush disaggregation and
eruption.
Logistics
If the student wishes to undertake fieldwork in Iceland, that will take place in the summer of 2016, at
localities decided in discussion with the supervisor. Sample preparation and microanalysis will take place in
the Department, with guidance from technical experts. The development of the models and data handling
will require the student to learn to code in a suitable language, probably R and Python, and the supervisor
will assist with those choices. There is also scope for summer work at experimental petrology labs in
Hanover, under the guidance of David Neave.
Finance
Funding for fieldwork or labwork in Hanover may be partly obtained by the student. Support for related
summer work may also be available. Funds are available to support the sample preparation and microanalysis. Database manipulation and model development have no costs.
Reading List
Manning, C.J. & Thirlwall, M. (2014). Isotopic evidence for interaction between Öræfajökull mantle and the
Eastern Rift Zone, Iceland, Contributions to Mineralogy and Petrology, 167, 959
Neave, D.A. et al.,(2014) Crystal storage and transfer in basaltic systems: the Skuggafjöll eruption, Iceland,
Journal of Petrology, 55, 2311-2346
Neave, D.A. et al.,(2013) Crystal–Melt Relationships and the Record of Deep Mixing and Crystallization in
the AD 1783 Laki Eruption, Iceland, Journal of Petrology, 54, 1661-1690
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Part III Projects 2016-17
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Topic:
Supervisors:
Investigating ocean circulation patterns during early rifting of Pangea: a multidisciplinary approach.
Morag Hunter, Liz Harper and Alex Piotrowski
The sedimentary sequences on the North Yorkshire Moors coastline were deposited during the earliest stages
of Jurassic extension. This period is associated with several extinction events culminating in the early
Toarcian Oceanic Anoxic Event, a period characterised by sudden and severe palaeoclimatic change and
enhanced global burial of organic carbon. Early break-up was characterised by the creation of many small
basins along the extending margin linking the warm and salty Tethys to the cooler and fresher Boreal Ocean
via the Transcontinental Laurasian seaway. The extant of Tethyan-Boreal connection through these shallow
corridors is likely to have been controlled by regional tectonics, affecting inter-basin sill depth, and eustatic
sealevel changes. The resulting ocean circulation may have affected regional heat and moisture transport,
with implications for local climate, continental runoff, nutrient supply, biological productivity and organic
preservation. The Cleveland Basin is one of these basins.
Previous studies (Caswell & Coe, 2014, 2015) have looked at changes in size and abundance of fauna over
this interval and correlated these with geochemical proxies for palaeoenvironmental indicators but there has
been very little work done to try to link these with the sedimentary record and basin circulation.
Geochemical tracers such as oxygen and neodymium isotopes have been used to try to reconstruct global
changes in ocean circulation, continental runoff and palaeoclimate, but the existing low resolution
palaeoproxy records have high variability (Dera et al., 2014) suggesting that these records are either subsampling cyclical Milankovich variability, or are biased by local river inputs, or the record has been
diagenetically altered. We will test this by measuring coupled oxygen and neodymium isotopes on fossil
carbonate and associated silicate sediment at higher resolution for just one part of the story to see if the early
Jurassic in Yorkshire shows evolution of discrete and not yet interconnected basins with local restricted
circulation during early extension, or a truly global OAE.
This project presents a unique opportunity to link sedimentary and ichnofacies variation with faunal analysis
and new Nd isotopic analysis to investigate local versus global change leading up to the Toarcian OAE.
Integration with the sedimentary and palaeobiological data will allow us to determine whether (1) the Nd
isotopes reflect advected Tethyan and Boreal seawater or change with local sediment input, (2) water masses
or local sediment source change with sea level cycles, and (3) correlate with productivity and/or preservation
of organic carbon.
Training
There will be an element of field work in North Yorkshire where the student will be trained in sedimentary
logging, trace fossil and fossil data collection. Back in Cambridge the student will undertake statistical
analysis of fossil data, sedimentary rock processing, elemental and radiogenic isotopic sample preparation in
a clean laboratory, measurement by inductively coupled mass spectrometer (ICPMS) and multicollectorICPMS, and interpretation of the resulting geochemical data.
References
Caswell, M.A., and Coe, A.L., The impact of anoxia on pelagic macrofauna during the Toarcian Oceanic
Event (Early Jurassic), Proceedings of the Geologists’ Association, 125, pp. 383-391 (2014).
Caswell, M.A., and Coe, A.L., Primary productivity controls on opportunistic bivalves during Early Jurassic
oceanic deoxygenation. Geology, 41, pp 1163-1166 (2015).
Dera G. et al., Nd isotope constraints on ocean circulation, paleoclimate, and continental drainage
during the Jurassic breakup of Pangea, Gondwana Research, Volume 27, Issue 4, pp. 1599-1615 (2014)
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Part III Projects 2016-17
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Topic:
Boron Isotope and B/Ca Study of Marine Carbonates During Over Glacial – Inter
Glacial Climate Transitions
Supervisors:
Sambuddha Misra, Mervyn Greaves and Harry Elderfield
Aims
Atmospheric CO2 (pCO2), a potent greenhouse gas, is one of the key modulators of global climate. A longterm record of pCO2-atmosphere is essential for understanding past climate changes and the factors
responsible for climate forcing. However, there are few direct archives of past variations in pCO 2atmosphere (viz. Antarctic / Greenland ice-core records) with limited temporal coverage. CO2 is a reactive
gas, which rapidly attains equilibrium between the surface ocean and the atmosphere, within the atmospheric
residence time of CO2 (CO2). This exchange between the surface ocean and the atmosphere implies that
changes in pCO2-Ocean and pCO2-atmosphere are coupled; so knowing one can provide information about
the other. Moreover, dissolved CO2 in seawater is the primary controller of surface seawater pH. Hence, a
long-term record of paleo-seawater pH change can provide a first order estimate of atmospheric CO2
concentrations.
A promising candidate for a paleo-pH tracer is the boron isotope composition of marine calcium carbonate.
The two dominant species of dissolved boron in seawater are the tetrahedral B(OH) 4– (~20%) and the
trigonal B(OH)3 (~80%). Boron speciation is pH controlled with the trigonally coordinated species being
isotopically heavier than the tetrahedrally coordinated one. As marine calcite predominantly incorporates
B(OH)4– in their lattice a knowledge of foraminifera based boron isotope record can be used as a paleo-pH
proxy to reconstruct changes in atmospheric CO2 over geologic timescales.
Methods
Foraminifera samples from ODP Site 1123 will be chemically cleaned and analysed for boron isotope ratio
and trace element composition by Inductively Coupled Plasma – Mass Spectrometry (ICP-MS).
Approximately 20 – 25 samples at a temporal resolution of 500 – 2000 yr (subject to availability) will be
selected across the last Glacial – Inter Glacial cycle and/or across MIS 11.
Logistics
This project is entirely lab based. Sample preparation and analyses will involve the following steps: (a)
sample picking under optical microscope – one week; (b) chemical cleaning of samples – two weeks; (c)
sample purification for boron isotope analyses – two weeks; (d) boron isotope and trace element analyses by
ICP-MS – one week; (e) data analyses and modeling – one week. For timely completion of the project it is
desirable that the student starts early.
Finances
Instrument running costs and the cost of chemicals for the analyses will be borne by the Godwin Laboratory
for Palaeoclimate Research. There are no other expenditures associated with this project.
Reading
(a) Pearson, P. N. and Palmer, M. R., (2000); Atmospheric carbon dioxide concentrations over the past 60
million years. Nature (Vol 406) Pg. 695-699
(b) Rae, J. W. B. et al., (2011); Boron isotopes and B/Ca in benthic foraminifera: Proxies for the deep ocean
carbonate system. EPSL (Vol 302) Pg. 403-413
(c) Hemming, N. & Honisch, B., (2007); Boron isotopes in marine carbonate sedimentsand the pH of the
ocean. In: Hillaire-Macrel, C., De Vernal, A. (Eds), Proxies in late Cenozoic paleoceanography, Vol. 1 (17).
Elsevier Science Ltd, Pg. 717-734
(d) Pagani M. et al., (2005); A critical evaluation of boron isotope pH-proxy: The accuracy of ancient ocean
pH estimates. GCA (Vol 69) Pg. 953-961
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Part III Projects 2016-17
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Topic:
Boron Isotopes of Marine Carbonates During Paleocene – Eocene Thermal Maxima
(PETM)
Supervisors:
Sambuddha Misra, Mervyn Greaves and Harry Elderfield
Aims
In the last 65 Ma (Cenozoic) of Earth history the PETM (55 Ma) was the warmest period with global
average temperatures estimated to be 8 – 12 ºC higher than modern day. Atmospheric CO2 (pCO2), a key
modulator of global climate, was estimated to be at its Cenozoic maximum during PETM. To understand the
atmospheric-pCO2 driven PETM global warming a clear knowledge of contemporary pCO2-atmosphere is
necessary. However, there are few direct archives of past variations in pCO2-atmosphere with limited
temporal coverage. CO2 is a reactive gas for which the surface ocean rapidly attains equilibrium with the
atmosphere within the atmospheric residence time of CO2 (CO2). This exchange between the surface ocean
and the atmosphere implies that changes in pCO2-Ocean and pCO2-atmosphere are coupled; so knowing one
can provide information about the other. Moreover, dissolved CO2 in seawater is the primary controller of
surface seawater pH. Hence, a long-term record of paleo-seawater pH change can provide us with a first
order estimate of atmospheric CO2 concentrations.
A promising candidate for a paleo-pH is the boron isotope composition of the marine calcium carbonate. The
two dominant species of dissolved boron in seawater are the tetrahedral B(OH)4– (~20%) and the trigonal
B(OH)3 (~80%). This speciation is pH controlled with the trigonally coordinated species being isotopically
heavier than the tetrahedrally coordinated one. As marine calcite predominantly incorporates B(OH)4– in
their lattice a knowledge of foraminifera based boron isotope record can be used as a paleo-pH proxy to
reconstruct changes in atmospheric CO2 over geologic timescales.
Methods
Foraminifera samples from ODP Site 1262 and 1267 will be chemically cleaned and analysed for boron
isotope ratio and trace element composition by Inductively Coupled Plasma – Mass Spectrometry (ICP-MS).
Approximately 20 – 25 samples (total) at a temporal resolution of ~10,000 yr (subject to availability) will be
selected across PETM.
Logistics
This project is entirely lab based. Sample preparation and analyses will involve the following steps: (a)
sample picking under optical microscope – one week; (b) chemical cleaning of samples – two weeks; (c)
sample purification for boron isotope analyses – two weeks; (d) boron isotope and trace element analyses by
ICP-MS – one week; (e) data analyses and modeling – one week. For timely completion of the project it is
desirable that the student starts early.
Finances
The cost of chemicals / analyses will be borne by the Godwin Research Lab. They are no other expenditure
associated with this project.
Reading
(a) Pearson, P. N. and Palmer, M. R., (2000); Atmospheric carbon dioxide concentrations over the past 60
million years. Nature (Vol 406) Pg. 695-699
(b) Zachos, J. et al., (2001); Trends, rhythms, and aberrations in global climate 65 Ma to present. Science
(Vol 92) 686-693
(c) Hemming, N. & Honisch, B., (2007); Boron isotopes in marine carbonate sedimentsand the pH of the
ocean. In: Hillaire-Macrel, C., De Vernal, A. (Eds), Proxies in late Cenozoic paleoceanography, Vol. 1 (17).
Elsevier Science Ltd, Pg. 717-734
(d) Pagani M. et al., (2005); A critical evaluation of boron isotope pH-proxy: The accuracy of ancient ocean
pH estimates. GCA (Vol 69) Pg. 953-961
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Part III Projects 2016-17