Marine Sediments
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OCEN 10: Foothill College
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Dr. Christopher DiLeonardo
Geology & Oceanography Departments
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General Oceanography
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The Process of
Sedimentation
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• Particles of material that accumulate on the sea floor
– Solid rock fragments, precipitated minerals, &
organism “hard parts” (shells, skeletons, etc.)
• Preserve evidence of the past
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– Provide information about sediment
transport, tectonics, climate,
ecosystems, etc.
– Rocks made from marine sediments
may contain fossils (preserved
portion of plant or animal), which
provide direct evidence of past life
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Sediment Types &
Sources
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4 Major Types of
Marine Sediments
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• Lithogenous
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• Biogenous
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• Hydrogenous
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• Cosmogenous
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Lithogenous
Sediments
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• Originate from continental land
masses, volcanic activity in the
open ocean, and/or glacial activity
• Major constituents include:
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Quartz (pure silicate… just Si & O)
Feldspars (K and Na silicates)
Mica (K, Al silicate)
Clay minerals
Rock fragments
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Basalt
(Oceanic crust)
Granite
(Continental crust)
Weathering of rocks rich in ferromagnesian
minerals produce clays (and Fe & Mg ions);
rocks rich in non-ferromagnesian minerals
generate silicate mineral grains
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Lithogenous Sediment
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Lithogenous Sediments
• Particle size is used to distinguish between
the various types of lithogenous sediment
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Biogenous Sediment
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Biogenous Sediments
• Organically produced
particles… namely, calcium
carbonate (CaCO3) or silica
(SiO2)
• Silica comes from diatoms
(algae) & radiolarians
(animals)
• Calcium carbonate mostly
from foraminifera (animals)
& coccolithophores (algae)
Coquina
Coral reef
material &
stromatolites
are other forms
of calcareous
deposits
Stromatolite Mounds
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Hydrogenous Sediment
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Hydrogenous Sediments
• Manganese Nodules
• Phosphorites
Hydrogenous Sediments
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Glauconite – greenish hydrous
Fe, K silicate of complex &
variable composition
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Carbonates – mostly biogenic,
but non-biogenic types also occur
Hydrogenous Sediments
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Evaporites – salt
minerals that precipitate
as sea water evaporates
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Metal Sulfides –
hydrothermal vent
deposits
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Cosmogenous Sediment
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Depositional Systems
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Depositional Systems
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• Neritic Sediment Deposits
– Found near the continents and show a variety
of particles sizes
– Mostly lithogenous sediment entering from
shore and transported across marine provinces
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• Pelagic Sediment Deposits
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– Fine grained sediments that collect slowly on
deep ocean floor
– Lithogenous, biogenous, and hydrogenous
sediments common (but in different regions)
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Neritic Depositional Systems
• Beach Deposits
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• Relict Sediments
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• Turbidites
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• Glacial Deposits
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• Stromatolites
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Pelagic Depositional Systems
• Abyssal clay
• Oozes
– Calcareous
– Siliceous
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Biogenous Sediment Accumulation
• Rate of accumulation depends on: sedimentation rate,
degree of preservation, & amount of other materials
(clays) deposited
Pelagic Sediment Deposits
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