Marine Depositional Environment Specificities

Continental Margins consist of

The shelf, slope, and rise

Continental shelf

the flat part of the edge of continent containing beaches and shallow waters

Continental slope

the big drop off

Continental rise

Where most of the sediment is deposited

Abyssal plain

true oceanic crust

Continental shelf size and crust detials:

Underlain by continental crust, averages 70 km wide today

Turbidity Currents

Under water avalanches that can carve submarine canyons

Turbidity currents deposit sediment

at the base of continental slope, and look similar to alluvial fans

Indus Fan

one of the largest turbidity current deposits

Turbidity currents are caused by some sort of disturbance, such as

Earthquakes, extreme storms, oversteepend slopes, gas hydrate sublimation

Gas hydrate sublimation

When CH4 in ice goes directly from a solid to a gas

Deep ocean basins are comprised of

The abyssal plain and MORs

Abyssal plains are (characteristics)

deep and very flat, averaging 4500-6000 m below the sea

Seamounts

underwater mountains

Accretionary wedges

wedges in rock where sediment accumulates

Most terrigenous sediment is carried to the deep ocean through

Settling from wind transport

Terrigenous sediment enters the ocean (location)

downwind of continents with good sediment sources

Biogenous Sediment

Hard parts of once-living organisms like shells, “tests”, teeth, and bones

Ooze

Sediment where composition is 30% or more biogenic

Reverse Dissolution of calcium carbonate:

Calcium carbonate dissolves in cold water and precipitates in warm water

Calcium Carbonate Organisms are more common in ________ water

warm

Silica organisms are more common in ______ water

cold

Diatoms

Silica algae with a ton of microscopic holes

Radiolarians

Silica protozoans which typically have glass spikes and appendages, which help them float

Coccolithophores

Calcium carbonate algae which group into spheres and are the primary component of chalk

Coccolith

Broken up coccolithophore spheres

Foraminifers

Calcium carbonate protozoans that look like shells or blobs

Calcareous ooze

Ooze mainly made of calcium carbonate organisms

Siliceous ooze

Ooze mainly made of silica organisms

Biogenic distribution depends upon:

Productivity, destructions/dissolution of organisms, dilution from other sediment sources

productivity

How much the lowest part of the food chain (algae) is thriving

CCD

The depth past which calcium carbonate dissolves

Oozes are usually deep water sediments because of:

Dillution, too much terriginous sediment near the surface

Microscopic ocean organisms that make up oozes mostly float near the surface, but ooze is at the bottom of the ocean. It gets down there through:

Fecal pellets

why does calcareous ooze tend to line up with Mid Ocean Ridges?

so that it doesn’t dissolve below CCD

Cold water can be found at the equator because of

upwelling

Hydrogenous sediments

Chemical precipitates directly out of ocean water

Hydrogenous sediments form in:

Restricted basin evaporites, manganese nodules, hydrothermal vents (ores)

Cosmogenous sediments

space dust

Water conditions of shallow carbonate environments

Clear water for photosynthesis, warm but not hot water, wave action to circle nutrients and refresh oxygen

A good example of accretion (aggradational coastline) is

A coral reef