OCE 1001 Quiz 2

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

They all precipitate from water oversaturated in their respective minerals

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

True

Oceanic ridges are cut by a number of transform faults, which offset spreading zones.

True

What is calcareous ooze

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

Continental shelf

a generally flat zone extending from the shore to the shelf break

Which are associated with a passive continental margin

a wide continental shelf turbidity currents, which are initiated here and flow down submarine canyons

Volcanic features on the ocean floor that are less than 1,000 meters (0.6 miles) tall are called:

abyssal hills or seaknolls

Ice rafting

associated with glacial deposits

ocean trench

deep linear scars on the deep-ocean floor caused by plate convergence

passive continental margins are characterized by all of the following except

deep-sea trenches

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

All of the following are examples of lithogenous sediment except

diatom ooze

Due to the very harsh environmental conditions, very few types of organisms are found in association with hydrothermal vents

false

Echo sounding is not a very reliable way to measure ocean depth because water is a poor transmitter of sound

false

Mid-ocean ridges are rises that occupy a small portion (around 10%) of the deep ocean basins.

false

Radiolarian tests are dissolved beneath the carbonate compensation depth

false

The three major provinces of the ocean floor are continental margins, deep-ocean basins, and submarine canyons

false

abyssal plain

flat depositional surfaces that cover extensive portions of the deep-ocean basins

The direction of motion along a seafloor transform fault is

in the same direction as the plates are spreading

Sediments derived from pre-existing rocks on land are called

lithogenous

Abyssal clay

lithogenous (terrigenous) sediment

Submarine canyon

narrow and deep valleys on continental slopes

All of the following statements are true of ocean sediments except

ocean sediments are thickest in pelagic waters overlying the oceanic ridges

New lithosphere is produced in association with

oceanic ridges

Along the margins of the Pacific are found most of Earths

oceanic trenches

Marine sediment with more than 30% biogenies material is called

ooze

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

Continental margin

shallow-water areas close to continents

The two relatively flat areas on the physiographic curve represent

some interior continental areas/coastal plains and abyssal plains on the ocean floor

All of the following are examples of hydrogenous sediment except

stromatolites

Oozes are uncommon on continental margins because

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

What is the calcite compensation depth, or CCD?

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

Relatively few abyssal plains are located in the Pacific Ocean due to

the presence of convergent active margins

A sediment-laden current that flows off the continental shelf is called a turbidity current

true

Black smokers are hydrothermal vents that discharge superheated water with high concentrations of metal sulfides.

true

Oceans with passive plate margins have continental slopes with more gradual slopes than oceans with active plate margins

true

The Pacific Ring of Fire is the seismically active area along the margins of the Pacific Ocean where earthquakes and volcanoes are common

true

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

true

The shape of Earths hypsographic curve can be used to support the existence of plate tectonics

true

the four main types of marine sediment include all of the following except:

zoogenous sediment

Based on this date, 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

Hydrothermal vents are seafloor cold seeps with high concentrations of sulfur and salts.

False

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 rocks (oldest layer)

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

Characteristics of active continental margins include all of the following except

broad continental shelves

Direct and indirect observations indicate that rivers on land are responsible for the formation of submarine canyons.

false

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

calcium carbonate

Directly seaward of the continental shelf is a more steeply sloping region called the

continental slope

Hypsographic curve

cumulative plot of area versus depth or elevation

What process(es) affect the shape and structure of continental shelves?

erosion of sediment major climate changes, such as ice ages exposition of sediment large fluctuations in sea level