Chapter 5 - Sediments

Completed

Sediment

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

weathering, erosion, biological activity, volcanism, space, chemical reactions

Sedimentation originates from:

Sand

sediment particle between 0.062 and 2 millimeters in diameter

Silt

sediment particle between 0.004 and 0.062 mil meter in diameter

Clay

sediment particle smaller than 0.004 millimeter in diameter; the smallest sediment size category

smaller

_____ particles are best transported by water and wind:

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

well

Calm environments produce _____ sorted sediments:

poorly

Environments with energy fluctuations produce _____ sorted sediments:

Sir John Murray & A. F. Renard

studied and classified sediment types in 1981 based on Challenger data

Terrigenous (Lithogenous) Sediments

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

Minerals

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

most abundant

Terrigenous are the ____ in the ocean (volume):

15 billion metric tons

_____ of terrigenous sediments are transported by rivers each year:

100 million metric tons

_____ of terrigenous sediments are transported as dust and volcanic ash:

Biogenous Sediments

sediment of biological origin; organisms can deposit calcareous (calcium-containing) or siliceous (silicon-containing) residue

solutions in rivers or dissolved an the ocean ridge

The compounds in biogenous originate from:

organisms incorporate compounds into their structures, which fall and accumulate on the ocean floor

Biogenous sediments accumulates when:

55%

Biogenous sediments cover _____ on ocean floor area:

Hydrogenous Sediments

a sediment formed directly by precipitation from seawater; also called authigenic sediment

submerged rock, ocean crust, hydrothermal vents, and river runoff

Hydrogenous sediments originate from minerals from:

manganese nodules and phosphorite nodules

_____ are the prominent hydrogenous sediments, occurring in deep sea beds

Cosmogenous Sediments

sediment of extraterrestrial origin

interplanetary dust or asteroids

Cosmogenous sediments originates from:

Microtektites

translucent oblong particles of glass, a component of cosmogenous sediment, forming from melting and solidifying of impacted crust

Neritic Sediments

continental shelf sediment consisting primarily of terrigenous material; neritos = of the coast

Pelagic Sediments

sediments of the slope, rise, and deep-wean floor that originate in the ocean; pelagios = of the sea

glaciers and icebergs

_____ deposit poorly-sorted sediment onto high-latitude continental shelves

high productivity on the continental margin

Neritic sediments often contain lots of biogenous material due to:

Lithification

conversion of neritic sediment into sedimentary rock by pressure or by the introduction of a mineral cement

Turbidites

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

38%

_____ of the deep seabed is covered by clays

2 mm per year

Terrigenous accumulation on the deep sea floor is about:

Ooze

sediment of at least 30% biological origin

Siliceous Ooze

ooze composed mostly of the hard remains silica-containing organisms

Calcareous Ooze

ooze composed mostly of the hard remains organisms containing calcium carbonate

1-6 cm per thousand years

Ooze accumulates at about:

Foraminifera

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

Pteropods

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

Coccolithophores

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

Calcium Carbonate Compensation Depth

the depth at which the rate of accumulation of calcareous sediments equals the rate of dissolution of those sediments

4500 m

The CCD is at about:

48%

About ____ of the surface of deep ocean basins is covered by calcareous oozes

Radiolarian

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

Diatoms

Earth’s most abundant, successful, and efficient single-called phytoplankton; diatoms have two interlocking valves made primarily of silica, contributing to biogenous sediment

much slower

Dissolution of siliceous material is _____ than calcareous material:

in the basins surrounding Antarctica due to nutrient abundance

Diatomaceous oozes are most common:

everywhere

Calcareous oozes are most common:

on the equator in the Pacific

Radiolarian oozes are most common:

the Pacific due to volcanic weathering and emission

Pelagic clays are most common in:

near the poles - Arctic and Antarctic ice sheets

Glacial marine sediments are most common:

Nodule

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

manganese, iron oxides, cobalt, nickel, chromium, copper, molybdenum, zinc

Nodules contain:

1 - 10 mm per million years

Manganese nodules grow at rates of:

20-50%

Manganese nodules are found on _____ of the Pacific Ocean:

continental rise of South Africa and the continental slope of California, Japan, Argentina

Phosphorite nodules are found on:

Evaporites

deposit formed by the evaporation of ocean water

salts precipitate out of evaporating water in lakes or landlocked seas

Evaporite formation:

Gulf of California, Red Sea, Persian Gulf

Evaporites form in the _____ today:

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

shallow areas with high productivity (less carbon, more pH)

Oolite sands are formed in:

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 of sediment and returning an intact plug of material

W. J. Sollas

theorized in 1899 that deep sea deposits could reveal much of the planet’s history

Stratigraphy

the branch of geology that deals with the definition and description of natural division of rock, specifcially, the analysis of relationships of rock strata

Paleoceanograhpy

the study of the ocean’s past

rock composition, microfossils, depositional patterns, geochemical/physical character

Deep sea stratigraphy utilizes variations in _____ to correlate distinctive sedimentary layers:

continental margins - away from the ridge

The thickest deposits of sediments are found at:

nuclei

Manganese nodules grow on _____ , being something like a shark tooth, shell fragment, or rock fragment

carbonate salts; sulfate salts; rock salt

Salt evaporite formation occurs in three steps: _____ first, _____ second, _____ third

Rafting

transport of sediment, rock, silt, and other land matter out to sea by ice and plants, with the deposition of the rafted material when the carrying agent disintegrates

Relicit Sediments

sediments deposited by processes no longer active

Dredge

cylindric or boxlike sampling device made of metal, net, or both, which is dragged across the bottom to obtain biological or geological samples

Acoustic (Seismic) Profiling

the use of seismic energy to measure sediment thickness and layering on the seafloor

clays

The finest and most easily transported terrigenous sediment:

diatomaceous

Ooze most common at high latitudes:

area ; volume

Biogenous sediments cover the most _____ while terrigenous sediments cover the most _____ :

Gulf of Mexico, South China Sea, Bay of Bengal

places with highest sediment concentration:

JOIDES Resolution

scientific vessel that frequently samples sediment

quartz and clay, both originating from granite

The two most common components of terrigenous marine sediments are:

Authigenic Sediment

sediment formed directly by precipitation from seawater

the continental slope and rise

72% of the total volume of all marine sediments are associated with:

terrigenous

The majority of neritic sediments are:

Atlantic

The thickness of the _____ sediment bottom is about 1 km:

Pacific

The thickness of the _____ sediment bottom is less than 0.5 km:

it has more rivers, smaller area, and not as many trenches

The Atlantic sediment bottom is thicker than the Pacific because:

small, single-celled, drifting, plant-like organisms or the small ones that feed on them

Organisms that make up ooze are:

with the greater acidity of the deeper with the ability to hold more CO2 and because cold pressurized water dissolves it easier

Calcium carbonate shells are dissolved easiest:

greater depths and polar regions

Siliceous oozes are prevalent at:

planktonic skeletons are compressed into fecal pellets of their predators, which can fall faster to the ocean bottom

Oozes take on the characteristics of overlying water because:

diatomaceous earth

Uplifted ooze deposits that are fine-grained and siliceous are called:

the HMS Challenger

Manganese nodules were discovered by:

nuclei of shark teeth, bone fragments, microscopic alga and animal skeletons, or small crystals

Manganese nodules form around:

absent sediment, bioturbation, or slow currents sweep sediments away

Manganese nodules aren’t buried on the ocean bottom because of:

carbonates (calcium carbonate), then gypsum (calcium sulfate), then sodium chloride

Evaporite precipitation occurs in the order of:

oolith

An individual grain of oolite sand is called an: