Chapter 4

The most likely place to find abundant manganese nodules is on the:

abyssal plain far from a continent.

coccolithophores

biogenous sediment

siliceous ooze

biogenous sediment

Sediment that begins as rocks on continents or islands is called:

lithogenous (terrigenous) sediment.

Sediments derived from pre-existing rocks on land are called:

lithogenous.

Calcium carbonate is most likely to dissolve in water with which characteristics?

lots of carbon dioxide and colder temperatures

The particles found in some sediment that suggests that an extraterrestrial impact event are:

tektites.

The most abundant mineral in lithogenous sediments is __________.

quartz

Calcareous ooze is found in cooler waters at depth around the world.

False

Which of the following is not an important control on oceanic sediment accumulation?

All of the above factors are important.

Ocean sediments provide all of the following mineral resources except:

Coal

Which of the following organisms are responsible for the creation of siliceous ooze?

Diatoms

The Wentworth scale is used to arrange the amount of sorting in a sediment deposit.

False

The deposition of radiolarian oozes is affected by the carbonate compensation depth.

False

Describe the origin, composition, texture, and distribution of lithogenous sediment.

Lithogenous sediment is derived from pre-existing rock that is weathered and transported to the oceans by streams, wind, glaciers, and gravity from land. The composition of lithogenous sediment reflects the material from which it was derived. The size of the sediment particles is dependent on the energy needed to lay down the deposit, as well as its sorting. Lithogenous sediment can be found nearly everywhere on the ocean floor.

What is the difference between neritic and pelagic deposits? Give examples of lithogenous sediment found in each.

Neritic (of the coast) deposits are found on continental shelves and in shallow water near islands; these deposits are generally coarse grained. Pelagic (of the sea) deposits are found in the deep-ocean basins and are typically finer-grained materials.

Which of the following conditions allows for calcareous ooze to be found beneath the CCD?

The ooze accumulates above the CCD and then is covered before being transported to deeper depths by sea floor spreading.

List the two major chemical compounds that comprise most biogenous sediment, as well as examples of the organisms that produce them.

The two most common chemical compounds in biogenous sediment are calcium carbonate (produced by foraminifers and coccolithophores) and silica (produced by diatoms and radiolarians).

Describe the process of how a deep-sea drilling ship such as the JOIDES Resolution obtains core samples from the deep ocean floor.

This ship has a tall metal drilling rig to conduct rotary drilling. The drill pipe is made up of individual sections that can be screwed together to make a single string of pipe. The drill bit, located at the end of the pipe string, rotates as it is pressed against the ocean bottom. A core can then be raised to the surface from inside the pipe.

Coastal sand dunes are usually well sorted due to winds.

True

Organisms that live on the ocean floor may be responsible for keeping manganese nodules from being buried in the sediment.

True

Texture refers to the size and shape of sediment particles.

True

The organisms that contribute to biogenous sediment are chiefly algae and protozoans.

True

Sediments that are poorly sorted were most likely deposited by:

a glacier.

ice rafting

associated with glacial deposits

turbidite

associated with submarine canyons and deep-sea alluvial fans

You take a sediment sample from the ocean floor at a depth of 5500 m. The area has low biological productivity and the CCD is at 4500 m depth. Your sample will probably consist of __________.

clay

Of the following sediments, which one(s) is/are considered hydrogenous?

coatings of metal sulfides near black smokers

tektites

cosmogenous sediment

Sediments with an extraterrestrial origin are called:

cosmogenous.

Which of the following contains calcium carbonate (CaCO3)?

foraminiferans

halite

hydrogenous sediment

metal sulfides

hydrogenous sediment

Salt beds of the U.S. Gulf Coast are __________.

hydrogenous sediments

Of the following environments, where would you expect to find large amounts of lithogenous sediment?

in deep trenches not far offshore

Pelagic clays contain lots of material that settles to the seafloor through the water column and are:

less than 30% biogenous material.

Sediments found on continental margins are called:

neritic

All of the following are hydrogenous sediments except:

stromatolites.

Marine sediments provide valuable clues about which of the following Earth history events?

the ancient geographical locations of ocean basins

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

All of the following are true concerning neritic sediment deposits except:

they are primarily composed of calcareous deposits of biological origin.

Tektites are glassy rock fragments created during impact events.

true

Sediments with all grains of about the same size are classified as __________.

well sorted