Title
Unravelling the behaviour of basaltic volcanoes by combining field observations, 4D
imaging of HPHT basaltic magma kinetics experiments and analytical investigations
Supervisors (including Title; Dr, Prof etc): Prof Mike Burton (SEES, University of Manchester), Dr
Margherita Polacci (SEES, University of Manchester), Prof Peter Lee (School of Materials,
University of Manchester), Dr Nolwenn Le Gall (School of Materials, University of Manchester), Dr
Fabio Arzilli (SEES, University of Manchester)
Primary Contact Name and Email: Prof Mike Burton ([email protected])
Is this a CASE studentship? NO
Introduction:
Basaltic volcanism is the most widespread volcanic activity on Earth. Basaltic eruptions can manifest
through different types of eruptive styles, from quiet lava emissions, to mild/moderate Strombolian
explosions, to more violent fire fountaining events and paroxysmal activity. Understanding basaltic
volcanism and its eruptive styles is therefore key to forecasting the impacts of eruptions. A crucial
limitation of previous work is that it has been predicated almost exclusively on the assumption of
equilibrium between melt, crystals and volatiles. The volcanological community has traditionally assumed
that the processes of basaltic magma degassing and solidification/crystallisation occur nearly
instantaneously in response to depressurisation associated with magma ascent and eruption. However, it
is now recognised that the timescales required to achieve equilibrium for both crystal growth (Vona and
Romano, 2013) and volatile exsolution (Pichavant et al. 2013; Lloyd et al. 2004) are longer than the
timescales of magma ascent in low viscosity basaltic magmas, meaning that basaltic eruptions are
particularly prone to disequilibrium processes. The impact of disequilibrium is profound because gas and
crystal content control magma viscosity, density, ascent rate, and the fragmentation process. These are
the dominant factors controlling the eruption style, which ultimately dictates the nature and scale of the
hazard posed. Quantifying disequilibrium processes in volcanic systems remains an enormous challenge:
the P, T, volatile content, melt composition and rate-of-ascent parameter space is huge, and, until now,
laborious experiments requiring interruption and quenching were required to capture each individual data
point. In addition, experimental work (Brugger and Hammer 2010; Arzilli and Carroll 2013)] on
crystallisation kinetics has been mostly done through the study of 2D textures. However, the texture of a
volcanic rock is the final product of a dynamic process, which is difficult to quantify with 2D
measurements. Magmatic crystallisation is generally considered as the growth of single crystals from the
melt, but growth could be related to a sequence of processes, from Ostwald ripening, to crystal
aggregation (Schiavi et al. 2009) or dissolution/formation of new phases, which significantly complicates
the understanding of crystal texture evolution in both space and time. This PhD project proposal will make
a breakthrough in understanding disequilibrium crystal kinetics in basaltic magmas by integrating
volcanological observations of basaltic eruptions with analytical work on basaltic erupted products and 4D
(space+time) X-ray microtomography imaging of HPHT crystallisation experiments in basaltic magmas.
The PhD project is directly linked to the recently awarded NERC Large Grant ‘Quantifying disequilibrium
processes in basaltic volcanism’ (DisEqm), based in the Schools of Earth and Environmental Sciences
and Materials in Manchester and led by Prof Mike Burton.
Project Summary:
The project will integrate field, experimental and analytical work. The PhD candidate will first review the
existing literature on the dynamics of basaltic eruptions and on crystallisation in basaltic magmas. The
student will be involved in at least one field trip to Italy or Iceland to study basaltic tephra deposits directly
in the field and collect samples of basaltic products from Mount Etna and/or Laki eruptions. The student
will then be engaged in performing 4D X-ray microtomography imaging of basaltic sample textures
produced during HPHT experiments of crystallisation kinetics at Diamond Light Source, the UK
Synchrotron in Harwell. The aim of such work will be to be able to visualise and quantify time sequences
of crystal (and vesicle) textures directly in 3D and link these features to disequilibrium processes in
basaltic conduits and the eruption dynamics. The X-ray microtomography experimental work will be
complemented by petrological and geochemical analyses of natural and experimental basaltic samples.
Results from field observations, 4D imaging and analytical work will be combined to produce an improved
holistic model of the dynamics of basaltic eruptions.
The student will be involved in a dynamic, international research group based in Manchester and Harwell
(Oxfordshire), and will travel abroad for conferences and fieldwork to an active, hazardous basaltic
volcano together with the other project partners.
We seek an able and enthusiastic individual with a strong background in geoscience or physical science
to join our volcanology research group. The project will suit a numerate candidate with enthusiasm for
field studies and analytical/experimental work. At the end of the project, the student will have gained a
broad range of practical, intellectual and interpersonal skills, opening multiple career opportunities, from
academia to industry or government roles.
Our studentships are funded by NERC and are available to UK nationals and other EU nationals who
have resided in the UK for three years prior to commencing the studentship. If you meet these criteria,
funding will be provided for tuition fees and stipend. Students from EU countries who do not meet the
residency requirements may still be eligible for a fees-only award. Overseas students may be able to join
the programme but will need to have arranged funding from other sources.
Image 1: A basaltic eruption
Image 2 Caption 3D X-ray microtomography view of volcanic pumice from Stromboli volcano (left) and 3D
view of reconstructed plagioclase crystals in the same sample (right).
References
Arzilli F, Carroll MR (2013) Crystallization kinetics of alkali feldspars in cooling and decompressioninduced crystallization experiments in trachytic melt. Contrib Mineral Petrol 166:1011-1027.
doi:10.1007/s00410-013-0906-1
Brugger CR, Hammer JE (2010) Crystal size distribution analysis of plagioclase in experimentally
decompressed
hydrous
rhyodacite
magma.
Earth
Planet
Sci
Lett
300:246–254.
doi:10.1016/j.epsl.2010.09.046
Lloyd SA, Ruprecht P, Hauri EH, Rose W, Gonnermann HM, Plank T (2014) NanoSIMS results from
olivine-hosted melt embayments: Magma ascent rate during explosive basaltic eruptions. J Volcanol
Geotherm Res 283:1-18. doi.org/10.1016/j.jvolgeores.2014.06.002
Schiavi F, Walte N, Keppler H (2009) First in-situ observation of crystallization processes in a basaltic
andesite melt with moissanite cell. Geology 37:963–966. doi: 10.1130/G30087A.1
Vona A, Romano C (2013) The effects of undercooling and deformation rates on the crystallization
kinetics of Stromboli and Etna basalts. Contrib Mineral Petrol 166: 491-509, doi: 10.1007/s00410-0130887-0