KIM3701 Marine Sediment

8/3/2019 KIM3701 Marine Sediment

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BIOGENOUS VS HYDROGENUS


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SEDIMENT

Sediment is a broad term used by geologists for anyparticulate matter that is transported by fluid flow.

The deposition of suspended matter on the bed or

bottom of a body of water by settling is known assedimentation.

In most places the sea floor is covered with a layer ofsediment.

The exceptions would be a newly formed volcanic

island or the bottom of a submarine canyon recentlyscoured by a turbidity current.

Sediment layers in the ocean are records of processesoccurring both in the oceans and on land.


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CLASSIFYING SEDIMENTS

Geologists group these sediment into 4 maingroups based on the origin or source of thesediment:1) Terrigenous Sediment

2) Biogenous Sediment

3) Hydrogenous Sediment

4) Cosmogenous Sediment


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Origin organic material

Remains of biological organisms

(animals & plants)

Biogenous Sediments

CLASSIFICATION OF MARINE

SEDIMENTS


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Biogenous sediments: Origin

Hard parts: shell, bones, teeth

Accumulates as biogenous sediment

Classified as either macroscopic or microscopicbiogenous sediment

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Biogenous sediments: Origin

MACROSCOPIC

Can be seen with bare eyes:

shells, bones, teeth

Not common (except coralreefs)

MICROSCOPIC

Microscopic organisms produce

tiny shells teststests sink after organism die

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Biogenous sediments: Microscopic

Microscopic tests accumulates in deposits called

Ooze(fine-grained mushy material)

Biogenous ooze must contain at least

30% biogenous test material (by weight)

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Biogenous sediments: Composition

Most common chemical compounds in

biogenous sediment are:

silica (SiO2) quartz

calcium carbonate(CaCO3) calcite


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Silica in biogenousooze

Radiolarians(protozoan) &

Diatoms (microscopic algae)

Biogenous sediments: Composition

Calcium carbonatein biogenous ooze

Foraminifera (protozoan) &

Coccolithophores(microscopic algae)


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Radiolarians (protozoa)

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Diatoms (microscopic algae)

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Foraminifers (protozoa)

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Coccolithophores (microscopic algae)

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Origin chemical precipitationof minerals dissolved in water

Hydrogenous Sediments

CLASSIFICATION OF MARINE

SEDIMENTS


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Hydrogenous sediments: Origins

Seawater contains many dissolved materials

Chemical reactions cause materials to come out ofsolution precipitate(from dissolved to solid

state)

Precipitation occurs as environmental conditions

change (temperature, pressure, salinity)


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Hydrogenous sediments: Composition

Many different composition

As the composition of the ocean itself


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Chemical composition of seawater

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Mineral Deposits

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Manganese nodules composition

Major components: MnO2 (30%) + FeO (20%)

Minor components (less than 1%) copper (wiring, pipe, brass and bronze)

nickel (stainless steel)

cobalt (strong magnets and steel tools)



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Manganese nodules

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Manganese nodules


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Mineral Deposits

Oolites

Formed from calcium carbonate and magnesiumcarbonate in warm, shallow productive waters

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Mineral Deposits

Phosphate deposits

Coatings on rocks & shallow water nodules (


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Mineral Deposits

Metal sulfides deposits

Associated with hydrothermal vents (mid-ocean ridge)

Contain: iron, nickel, copper, zinc, silver,

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Mineral Deposits

Evaporite deposits

Restricted circulation + high evaporation saturation

Chemical precipitation

Examples: halite (rock salt) + gypsum (CaSO4)

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Biogenous sediments


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Hydrogenous sediments

Documents

KIM3701 Marine Sediment