OCE1001 HW 4

All the following are examples of lithogenous sediment:

- beach sand - glacial deposits - clays - volcanic particles

The four main types of marine sediment are:

- cosmogenous sediment - biogenous sediment - lithogenous (terrigenous) sediment - hydrogenous sediment

All the following are examples of hydrogenous sediment:

- halites - phosphates - manganese nodule - evaporites

Based on this data, choose the statement that offers the best explanation for the differences in sediment abundance between the Atlantic and Pacific basins.

Abyssal clays are more abundant in the Pacific than the Atlantic because calcareous oozes dissolve before reaching the sea floor in the latter ocean basin.

What would happen if the depth of the CCD were above the top of the mid-ocean ridge?

Calcareous ooze would not be found below the CCD.

True/False: Radiolarian tests are dissolved beneath the carbonate compensation depth

False

ooze

Marine sediment with more than 30% biogenous material

ice rafting

associated with glacial deposits

Marine sediments that originate in the warm tropical surface ocean would create deposits in the deep sea composed primarily of ___________

calcium carbonate

What three steps are required for calcareous ooze to exist below the CCD?

deposition of calcite shells above the CCD, cover of these shells by a non-calcareous material, and movement of the sea floor over millions of years

lysocline

depth at which calcium carbonate begins to dissolve

What can you infer about the ocean environment from a core sample composed of the following layers: 1. siliceous ooze (youngest layer) 2. calcareous ooze 3. basalt rock (oldest layer)

The core was collected in a region of high surface productivity in water deeper than 4,500 meters.

What do manganese nodules, metal sulfides, and evaporites all have in common?

They all precipitate from water oversaturated in their respective minerals.

True/False: Calcareous shells generally will not accumulate on the ocean floor when the water depth exceeds about 4,500 meters (around 15,000 feet)

True

True/False: The organisms that contribute to biogenous sediment are chiefly algae and protozoans

True

What is calcareous ooze?

a fine-grained, deep ocean sediment containing the skeletal remains of calcite-secreting microbes

Sediments derived from pre-existing rocks on land are called

lithogenous

abyssal clay

lithogenous (terrigenous) sediment

A sediment sample dominated by microscopic lithogenous sediment grains would be classified as a ___________

pelagic deposit

Neritic sediments are most likely to be composed of __________

sand, silt, and gravel

What is the calcite compensation depth, or CCD?

the ocean depth below which calcite is unstable and will dissolve quickly

All the following statements are true of ocean sediments:

- ocean sediments may form from the remains of living organisms falling to the ocean floor - ocean sediments include the remains of ancient rocks of cosmic origin. - ocean sediments can include the fossilized remains of ancient marine life. - ocean sediments may be composed of chemical precipitates such as calcium carbonate or manganese dioxide.

Oozes are uncommon on continental margins because __________

the biogenous component tends to be overwhelmed by the amount of lithogenous material derived from the nearby continent