oceanography chapter 4 hw
The tests from which of the following organisms will dissolve below the CCD?
foraminifera coccolithophores
Why doesn't siliceous ooze dissolve after it accumulates on the seafloor?
once deposited on the seafloor, siliceous organisms bury each other
What is the limiting factor in determining the accumulation of siliceous ooze/calcareous ooze, respectively?
productivity/water depth
How are seafloor sediments useful in reconstructing past ocean conditions?
sediments that accumulate on the seafloor provide information about ocean conditions at the time that the sediment was deposited. changes in the composition of the seafloor sediment reflect changes in the depositional environment.
Which of the following materials would constitute biogenous sediment? Choose all that apply.
shark teeth microscopic shells whale bones
Which of the following organisms thrive in cold surface waters? Choose all that apply.
siliceous organisms radiolarians diatoms
Which of the following sediments would you expect to find in a lagoon?
broken bits of coral salt
Where might one find calcareous oozes on the seafloor? Choose all that apply.
buried beneath abyssal clay buried beneath siliceous oozes along the crests of mid-ocean ridges, above the CCD
Where do calcareous oozes exist on the seafloor?
underneath areas where calcareous organisms live, above the CCD.
What process allows siliceous organisms to thrive in areas along the equator?
upwelling
What is the approximate depth of the calcite compensation depth (CCD) in the ocean?
3 miles (4.5 kilometers)
On average, at what ocean depth does calcite readily dissolve into seawater?
4500 meters (14,764 feet)
Where in the figure above would you expect to find the accumulation of siliceous ooze? (https://session.masteringgeology.com/problemAsset/2461915/3/MGEO_2461915_E.jpg)
D
What common household item is used in this video to demonstrate rotary drilling?
an apple corer
What did the discovery of tillite in South Africa reveal about southern Africa's past?
an ice sheet covered southern Africa 300 million years ago
What is calcareous ooze composed of?
at least 30% the remains of calcareous organisms
Why is this drilling process called rotary drilling?
because the drill bit turns around in a circle
Why does calcareous material dissolve below the CCD?
below the CCD, weak acid is formed, which dissolves calcareous material.
Which of the following are examples of pelagic sediments?
biogenic ooze volcanic dust abyssal clay
What have oceanographers determined from analyzing sea floor cores?
climate change and past extinctions
What conditions exist below the CCD?
cold temperature high carbon dioxide concentration high acidity
Why might ocean floors be better than continental locations for studying long-term changes in the size of ice sheets?
continental records are fragmented and discontinuous, missing parts of the climate record
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
Which of the following materials could form a siliceous ooze? Choose all that apply.
diatoms silicoflagellates radiolarians
The two major types of microscopic, planktonic organisms that produce siliceous oozes are __________ and __________.
diatoms; radiolarians
Generally, what has been the pattern of global temperature change during the past 70 million years?
earth's average temperature is approximately 15° cooler now than than it was 70 million years ago
Which of the following are examples of neritic sediments? Choose all that apply.
evaporite deposits beach sand
Siliceous ooze is particularly abundant on the seafloor at __________ and at __________.
high latitudes; equatorial upwelling zones
Where would you expect to find a high concentration of siliceous ooze?
off the coast of alaska near the equator in areas of upwelling surrounding antarctica
In which setting would calcareous ooze be most likely to form?
on the crest of a seamount under warm surface water
Where on the ocean floor do abyssal clays develop?
on the deep-ocean floor, far from land
Which of the following factors affect the distribution of biogenic oozes on the seafloor?
seafloor spreading dissolution biological productivity water depth
How does siliceous ooze accumulate on the seafloor if silica-based residues are dissolved slowly at all depths?
silica tests accumulate faster than seawater can dissolve them
Where would you expect to find a high concentration of calcareous ooze?
surrounding hawaii along the crest of the mid-atlantic ridge
In the demonstration, what does the apple represent?
the deep sea floor
What is the calcite compensation depth, or CCD?
the ocean depth below which calcite is unstable and will dissolve quickly
What conditions are necessary for siliceous ooze to accumulate on the seafloor?
the surface waters must be nutrient-rich
What is calcareous ooze?
a fine-grained, deep ocean sediment containing the skeletal remains of calcite-secreting microbes
Sediments derived from the remains of the hard parts of once-living organisms are called __________ sediments.
biogenous
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
Which sediment below cannot accumulate below the CCD?
calcareous tests
Two common types of chemical compounds found in biogenous sediments are __________ and __________.
calcium carbonate; silica
Forams, which are composed of calcium carbonate, __________ above the CCD and __________ below the CCD.
do not dissolve; dissolve
Diatomaceous earth, which is composed of silica, __________ above the CCD and __________ below the CCD.
does not dissolve; does not dissolve
How does the analysis of forams in ocean sediment cores reveal climate change?
the presence and relative dominance of different species of forams reveal different global climate conditions
Why do some organisms thrive in warm surface waters?
warm water is generally saturated in carbonate
