marine sediments types (detailed)
DESCRIPTION
Lithogenous, Biogenous, Hydrogenous, and Cosmogenous sediment are explained in detail in this powerpoint.TRANSCRIPT
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Silica in Biogenous Sediments
DiatomsPhotosyntheti
c algaeDiatomaceous
earth Radiolarians
ProtozoansUse external
food
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Silica in Biogenous Sediments
Tests from diatoms and radiolarians generate siliceous ooze.
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Calcium Carbonate in Biogenic Sediments
Coccolithophores Also called nannoplankton
Photosynthetic algae
Coccoliths – individual plates from dead organism
Rock chalk Lithified coccolith-
rich ooze
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Calcium Carbonate in Biogenic Sediments
Foraminifera ProtozoansUse external
foodCalcareous
ooze
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Distribution of Biogenous Sediments
Depends on three processes: Productivity Destruction Dilution
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Neritic Deposits
Dominated by lithogenous sediment, may contain biogenous sediment
Carbonate Deposits Carbonate minerals containing carbon trioxide
(CO3 ) Marine carbonates primarily limestone –
CaCO3 Most limestones contain fossil shells
Suggests biogenous origin Ancient marine carbonates constitute 25% of
all sedimentary rocks on Earth.
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Carbonate Deposits
Stromatolites Fine layers of
carbonate Warm, shallow-
ocean, high salinity Cyanobacteria
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Sea Floor Spreading and Sediment Accumulation
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Distribution of Modern Calcium Carbonate Sediments
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Hydrogenous Marine Sediments
Minerals precipitate directly from seawaterManganese nodulesPhosphatesCarbonatesMetal sulfides
Small proportion of marine sediments
Distributed in diverse environments
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Manganese Nodules
Fist-sized lumps of manganese, iron, and other metals
Very slow accumulation rates
Grows ~1 centimeter over several million years
Many commercial uses
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Phosphates and Carbonates
Phosphates Phosphorus-bearing Occur beneath areas in surface ocean of very
high biological productivity Economically useful as fertilizer
CarbonatesAragonite and calciteOolites
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Metal Sulfides
Metal sulfides Contain:
Iron Nickel Copper Zinc Silver Other metals
Associated with hydrothermal vents
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Evaporites Evaporites
Minerals that form when seawater evaporates
Restricted open ocean circulation
High evaporation rates
Halite (common table salt) and gypsum
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Cosmogenous Marine Sediments
Macroscopic meteor debris
Microscopic iron-nickel and silicate spherules (small globular masses) Tektites Space dust
Overall, insignificant proportion of marine sediments
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Worldwide Marine Sediment Thickness
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Resources from Marine Sediments
Energy resourcesPetroleum
Mainly from continental shelves
Gas hydrates Sand and gravel (including tin, gold, and
so on) Evaporative salts Phosphorite Manganese nodules and crusts
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Mining Sea Salt
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Distribution of Manganese Nodules