Oceanography - Sediments - Chapter 5

well-sorted sediments

A sediment in which particles are of uniform size.

poorly-sorted sediments

A sediment in which particles of many sizes are found.

pteropods

A small planktonic mollusk with a calcareous shell, which contributes to biogenous sediments.

biogenous sediment

Sediment of biological origin. Organisms can deposit calcareous (calcium containing) or siliceous (silicon-containing) residue.

cosmogenous sediments

Sediment of extraterrestrial origin.

pelagic sediments

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

ooze

Sediment of at least 30% biological origin.

minerals

A naturally occurring inorganic crystalline material with a specific chemical composition and structure.

clamshell sampler

A sampling device used to take shallow samples of the ocean bottom.

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.

turbidites

A terrigenous sediment deposited by a turbidity current; typically, coarse-grained layers of nearshore origin interleaved with finer sediments.

coccolithophore

A very small planktonic alga carrying discs of calcium carbonate, which contributes to biogenous sediments

neritic sediments

Continental shelf sediment consisting primarily of terrigenous material.

lithification

Conversion of sediment into sedimentary rock by pressure or by the introduction of a mineral cement.

evaporites

Deposit formed by the evaporation of ocean water.

diatoms

Earth's must abundant, successful, and efficient single-celled phytoplankton. They possess two interlocking valves made primarily of silica. The valves contribute to biogenous sediment.

sand, silt, and clay

Fine particles that make up most marine sediments

oolite sands

Hydrogenous sediment formed when calcium carbonate precipitates from warmed seawater as pH rises, forming rounded grains around a shell fragment or other particle.

foraminiferan

One of a group of planktonic amoeba-like animals with a calcareous shell, which contributes to biogenous sediments

radiolarian

One of a group of usually planktonic amoeba-like animals with a siliceous shell, which contributes to biogenous sediments.

calcareous ooze

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

siliceous ooze

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

sediment

Particle of organic or inorganic matter that accumulate in a loose, unconsolidated form.

terrigenous sediments

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

authigenic sediments

Sediment formed directly by precipitation from seawater. Also known as hydrogenous sediment.

nodules

Solid mass of hydrogenous sediment, most commonly manganese or ferromanganese nodules and phosphorite nodules.

stratigraphy

The branch of geology that deals with the definition and description of natural divisions of rocks; specifically, the analysis of relationships of rock strata.

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 not calcium carbonate.

paleoceanography

The study of the ocean's past.

microtektites

Translucent oblong particles of glass, a component of cosmogenous sediment