Marine Sediments and
Sedimentary Rocks
Interest in Marine Sediment
• Sediments reveal
– Past climates
– Ocean floor movements
– Circulation patterns
– Nutrient supplies
– Ocean chemical history
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Rock Cycle
1.
2.
3.
4.
5.
6.
7.
Sediments deposited
Lithification
Burial, compression
Deformation, melt
Re-crystallization
Tectonic uplift
Weathering and further deposition
Prof. Rosenheim
EENS/EBIO 223
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7
5
3
1
4
2
Introductory Oceanography
1
Sedimentary Rock
• Deposited in horizontal layers
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Strata (s. Stratum) –
horizontal layers
deposited on top of one
another
Law of Superposition
Sedimentary layers are deposited in a time sequence,
with the oldest on the bottom and the youngest on the
top.
Nicholas Steno
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Retrieval of Ancient Marine
Sediment
• Drilling ships needed to access oldest
marine sediments under sea – R/V JOIDES
Resolution
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
2
Retrieval of Ancient Marine
Sediment
• Drilling ships now can theoretically drill to
mantle – R/V Chikyu is a riser drilling
platform
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Drill Ship Operations
• Core through sediment layer
– Continuously pull core sections to the
surface for analysis
• Find hole with sonar beacon
– Ship uses thrusters for this purpose –
dynamic positioning
• Rotary drill or Riser drill into
compacted, lithified layers below the
sediment
– Continuously bring core sections to
surface for analysis
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Sediment Coring
• http://www.iodp.org/coring-procedure/
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
3
Marine Sedimentation
• Lithogenous Sediment
– Generated from pre-existing rock material
• Biogenous Sediment
– Originating from living organisms
• Hydrogenous Sediment
– Precipitated from dissolved material in water
• Cosmogenous Sediment
– Sourced extraterrestrially
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Sedimentation
• Energy dependent
• Smallest grains in basins
• Coarse grains nearer
coasts
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
From Sediment to Rock
• Lithification
– Sediment compaction
– Cementation
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Figure: Dr. Bruce Railsback, UGA
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Sampling Lithified Marine Sediment
• http://www.iodp.org/deep-sea-drilling/2/
• http://www.iodp.org/rotary-drilling/2/
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Core Analysis
•
•
•
•
Retrieve core
Non-destructive analysis
Split
Measure and analyze
– Sample (one half)
– Archive (the other half)
• http://www.iodp.org/coreanalyzing-process/2/
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Sediment History
• What changes in sediment type ratios are
there? (lithogenous vs. biogenous)
• How does biogenous sediment change
through time? (biogenous)
• What evidence of impact sediments is
apparent? (cosmogenous)
• How has ocean chemistry changed in the
past? (hydrogenous and biogenous)
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
5
Lithogenous Sediment
• Generated from pre-existing rock
• Weathering, erosion, transport to ocean basin
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment Deposition
• Neritic deposits – continental margins and
islands, dominated by lithogenous
sediment
• Pelagic deposits – deep ocean basins
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment Sources
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
6
Lithogenous Sediment Composition
• SiO2
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment Transport
• Water
– Terrigenous sediment
transported in rivers
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment Transport
• Water
– Deposited in basins
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
photo: Lonnie Leithold
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Lithogenous Sediment Transport
• Air
– Loess
• Wind blown dust
• Finer material
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Quartz Distributions – Wind
Transport
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment Transport
• Ice
– Calving ice sheets and
glaciers
– Large, coarse fragments
– Carried long distances by
icebergs
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
8
Lithogenous Sediment Transport
• Ice-rafted debris
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment Transport
• Ice-rafted debris
– High rates of glaciation
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment Transport
• Sea level change
– Direct erosion of
vulnerable coastline
– Transport out to sea and
deposition in basin
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
9
Lithogenous Sediment Transport
• Volcanoes
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment Transport
• Tephra layers
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment Maturation
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
10
Lithogenous Sediment Maturity
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Turbidites – From Neritic to Pelagic
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Turbidites – From Neritic to Pelagic
• Gravity transport – density current
– underwater landslide
• Unique depositional record
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
11
Turbidites – From Neritic to Pelagic
• Gravity transport – density current
– underwater landslide
• Unique depositional record
• High rate of speed
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment
• Which ocean has the highest proportion of
lithogenous sediments?
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Lithogenous Sediment
• Which ocean has the highest proportion of
lithogenous sediments?
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
12
Biogenous Sediment
• Sediment originating from living organisms
– Foraminifera
– Coccolithophorids
– Radiolarians
– Diatoms
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Calcareous Biogenic Sediment
• Ca2+ + CO32-
Prof. Rosenheim
EENS/EBIO 223
CaCO3 (s)
Introductory Oceanography
Calcareous Biogenous Sediment
• Calcareous Organisms
– Foraminifera
– Coccolithophorids
– Pteropods
White cliffs of Dover (England)
are made of chalk deposited in
the Cretaceous Period. These
cliffs are almost entirely made of
coccoliths from ancient
coccolithophorids.
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
13
Coccoliths and Coccolithophorids
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Coccoliths and Coccolithophorids
Coccoliths
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Coccolithophorids
• Floating algae
• Build coccoliths for protection and perhaps
light manipulation
• Responsible for 25%
CO2 sequestration by
oceans every year
http://www.jochemnet.de/fiu/bot4404/BOT4404_16.html
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
14
Coccolithophorids
• Dominant during Cretaceous Period
– “creta” Latin for chalk
• Abundant in shallow inland seas
• Warm and tropical
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Pteropods
Swimming sea
snails, some form
tine snail-type
calcareous shells.
These form a small
part of calcareous
sediment.
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Foraminifera
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
15
Foraminifera
Foraminifera are floating and
benthic protists (first ones –
Greek for early life forms) . They
form complex calcareous shells
(tests) and use a cellular “net” to
trap food. Those living in the
surface of the oceans are
normally symbiotic with
photosynthetic algae.
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Foramifera
• Planktonic forams
– Surface dwellers
– Need and use light
– Symbiosis
– Tests fall to bottom
upon death
O.R. Anderson
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Foramifera
• Benthic Forams
– Dwell bottom
sediments
– Leave shells mixed
with planktic species
upon death
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
16
Foraminifera Records
• Many species are geologically short-lived,
making them useful for paleontologist to
date rocks
• Also useful for paleoceanography
– Assemblages tell of climate change and
extinctions
– Test (or shell) chemistry tells of global climate
change
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Foraminifera and
Paleoceanography
• Cesare Emiliani –
Father of
Paleoceanography
• Sir Nicholas
Shackleton – Emiliani’s
counterweight
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Foraminifera and
Paleoceanography
• Cesare Emiliani – isotopic change
of oceans, recorded in foram tests,
is related to temperature
• Sir Nicholas Shackleton – isotopic
change of oceans is related to
isotopic composition of oceans
• Answer – Both.
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
17
Foraminifera and
Paleoceanography
Whereas temperature probably played a large role in the
isotope composition of planktic foraminifera, Shackleton
measured benthic species which also showed change. We
know that the deep oceans are fairly resistant to temperature
change. Deep benthic foraminifera showing isotope variations
meant that the isotope composition of the water had changed in
concert with the temperature. More ice meant heavier values in
the oceans. Cold temperatures meant heavier values in the
oceans. Benthics vs. planktics offered a solution to this
argument.
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Siliceous Biogenic Sediment
• Diatoms
– Planktonic
– Photosynthetic
• Radiolarians
– Planktonic
– Heterotrophic
• Siliceous Ooze
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Diatoms
Photosynthic plankton with two
halves (frustules). Like radiolarians,
these collect in areas of high
productivity.
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
18
Radiolarians
Noted for their beauty, are best
preserved in areas of high
productivity where they rain at a
higher rate than dissolution.
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Siliceous vs. Calcareous Ooze
• Siliceous
deposits form
in tropics and
Antarctica –
high
productivity
• Calcareous
deposits form
where ocean
chemistry
allows
preservation of
delicate
carbonate tests
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Carbonate Compensation Depth
• Lysocline
– Stability of CaCO3 is related to temperature and pH
– Lower temperatures dissolve more CO2, making
water more acidic
– CaCO3 tends to dissolve when temperatures are low
(i.e. deep water)
• CCD
– Where dissolution of CaCO3 balances production and
CaCO3 can no longer accumulate
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
19
Siliceous vs. Calcareous Ooze
• Pacific is
largely
below
present day
CCD.
• Abyssal
clay is
undiluted
here
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Productivity and Preservation
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Productivity and Preservation
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
20
CCD and Lysocline
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
CCD and Lysocline
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Sedimentation on the Ocean Floor
• Sediment grows thicker away from midocean ridge (spreading center)
• Oldest (thickest) sediment found toward
continental margins
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
21
Biogenous Sediments in Neritic
Zone
• Coral reefs
– Calcium carbonate
skeletons
– Fragments
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Biogenous Sediments in Neritic
Zone
• Mollusks
– Calcium carbonate
skeletons
– Shell hash
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Hydrogenous Sediments
• Forming from within the water column
– Precipitation from dissolved constituents of
seawater
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
22
Whitings – Calcium Carbonate
• Oceans can be supersaturated with
regards to calcium carbonate (surface)
• Whitings
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Why so blue?
• Reflection of light through shallow waters
and white carbonate sands.
– Biogenous
– Hydrogenous
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Manganese Nodules
• Manganese, iron, and other metals
– 5 cm in diameter, layered
– Nucleates around a pre-existing grain
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
23
Ooids – Calcium Carbonate
• Round grains of layered calcium
carbonate
• Formed by repeated agitation in shallow,
supersaturated water
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Ooids – Calcium Carbonate
• Make wonderful beach sand because of
uniform spherical shape
• Lithified to oolite
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Metal Sulfides – Black Smokers
• Precipitation of reduced chemicals in
hydrothermal vent fluids
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
24
Cosmogenous Sediments
• Derived from extraterrestrial sources
– Spherules
– Meteorite debris
Microscopic debris
• Tektites
• 300,000 tons of space debris reach
Earth’s surface every year
• Macroscopic debris is more rare
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Impact Debris
• Large impacts have been
responsible for dramatically
altering Earth’s conditions
– Extinctions evidenced by impact
debris
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
Impact Debris
• Would the Permian extinction
impact event (if there was
one) be observable in ocean
sediments?
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
25
Key Concepts
•
•
•
•
•
Sediment types and genesis
Transport and deposition
Preservation
Uses of sediment records
Sampling techniques
Prof. Rosenheim
EENS/EBIO 223
Introductory Oceanography
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