Ch 5 Oceanography Sediments Vocabulary

piston corer

A seabed-sampling device capable of punching through up to 25 meters (80 feet) of sediment and returning an intact plug of material.

poorly sorted sediment

A sediment in which particles of many sizes are found.

Evaporites

An important group of hydrogenous deposits that include many salts important to humanity.

Would you say the "memory" of sediments is long or short (in geologic time)?

Because the deep sea sediment record is ultimately destroyed in the subduction process, the ocean's sedimentary "memory" does not start with the oceans formation (which was early reasoning)

How does the CCD affect the ooze deposition at great depths?

Below this depth the tiny skeletons of calcium carbonate dissolve on the seafloor, so no calcareous oozes can accumulate

neritic sediment

Continental shelf sediment consisting of mainly terrigenous material

How do evaporites form?

Evaporites are hydrogenous deposits that include salts that salts precipitate as water evaporates from isolated arms of the ocean or from landlocked seas or lakes.

Minerals

Inorganic crystalline substances found naturally in the earth with specific chemical compositions

terrigenous sediment

Most abundant Sediment derived from the land and transported to the ocean by wind and flowing water.

How do neritic sediments differ from pelagic ones?

Neritic sediments consist primarily of terrigenous material. Deep-ocean floors are covered by finer sediments than those of the continental margins Sediments of the slope, rise, and deep-ocean floor that originate in the ocean are called pelagic sediments.

Is there a compensation depth for the siliceous components of once-living things?

No its made up of algae called diatoms that dissolves very slowly at all depths

siliceous ooze

Ooze composed mostly of the hard remains of silica-containing organisms

calcareous ooze

Ooze composed of mostly the hard remains of organisms containing calcium carbonate

Oolite sands

Sands composed of ooliths; abundant in warm, shallow waters like the bahamas

How might past climate be inferred from studies of marine sediments?

Scientists have instruments capable of analyzing very small variations within carbonate shells of fossils found in deep sea sediments. they can interpret changes in temp. of surface and deep water over time

pelagic sediment

Sediments of the slope, rise, and deep-ocean floor that originate in the ocean.

What sediments accumulate most rapidly? Least?

Terrigenous is quickest, Cosmogenous is slowest

which type of sediment is most abundant

Terrigenous sediments are the most abundant. The largest terrigenous deposits form near continental margins.

calcium carbonate compensation depth (CCD)

The depth at which the rate of accumulation of calcareous sediments equals the rate of dissolution of those sediments. Below this depth, sediment contains little or no calcium carbonate.

How have studies of marine sediments advanced our understanding of plate tectonics?

The discovery that marine sediments are comparatively young (to terrestrial sed.) is a prime proof of tectonic theory (SUBDUCTION ZONES!)

Lithification

The process that converts neritic sediments into solid rock by compaction or cementation.

Paleoceanography

The study of the ocean's past.

what products containing marine sediments have you used today?

Toothpaste contains finely-ground diatomaceous residue, gravel for concrete is often of marine origin, gasoline, heating oil, natural gas, and the raw material of plastics

Microtektites

Translucent oblong particles of glass, a component of cosmogenous sediment. Formed by the violent impact by large meteors on the crust of the earth.

turbidity current

a downslope movement of dense, sediment-laden water from dislodged sand and mud on the continental shelf and slope

Foraminifera

a main component of calcareous ooze, small mollusks

Coccolithophores

another component of calcareous ooze, tiny algae

Is the thickness of ooze always an accurate indication of the biological productivity in a given area

beyond certain depths, both calcareous and siliceous ooze will tend to dissolve in the water. So you're not able to tell

which type of sediment covers the greatest seabed area?

biogenous sediments

How are sediments classified?

by particle size and origin

which type of sediment is rarest?

cosmogenous sediment

ooze

deep-ocean sediment containing at least 30% biogenous material

What type of particles compose most marine sediments?

finer particles: sand, silt, clay

authigenic sediment

formed in the place it occupies aka hydrogenous

Radiolarian

forms siliceous ooze, amoeba-like animal

Diatoms

forms siliceous ooze, single celled algae

Turbidites

graded layers of terrigeneous sand interbedded with finer pelagic sediments of the deep sea floor due to turbidity currents

cosmogenous sediment

least abundant; sediment derived from outer space from interplanetary dust and impacts by astroids/comets and typically greatly diluted by other sediments

Why are very few areas of the seabed completely free of sediments?

marine processes that generate sediments are widespread

Sediment

matter that settles to the bottom of the seafloor. Occurs in a broad range of sizes and types

hydrogenous sediment

minerals that have precipitated directly from seawater. ex) manganese nodules, phosphorite nodules

How do hydrogenous materials form? es of h sediment

most originate from chemical reactions that occur on particles of the dominant sediment. ex) manganese nodules

biogenous sediment

organic; accumulation of hard parts of some marine organisms, calcareous and siliceous

What is the origin of oozes?

remains of small single celled drifting plant like and animal organisms

Other than petroleum and natural gas, what is the most valuable material taken from marine sediments?

sand and gravel

well sorted sediment

sediments composed of particles of mostly one size

How do well-sorted sediments differ from poorly sorted sediments?

sorting is a function of the energy of the environment-the exposure of that area to the elements

four main types of marine sediments

terrigenous, biogenous, hydrogenous, cosmogenous

Are neritic sediments generally terrigenous or biogenous?

terrigenous, eroded from the land and carried to streams which transports them to the ocean

Why are Atlantic sediments generally thicker than Pacific sediments?

the atlantic bottom is covered to a thickness of 1km while the pacific is 0.5km

Example of lithified sediment on land

the grand canyon aka the colorado plateau

Stratigraphy

the study of layered sedimentary deposits and the sequence of events they reflect