Since calcareous ooze is formed from the hard parts of the bodies of free-floating organisms, this means that unlike ooids, which are nearshore sediments, and unlike reefs, which require shallow water, calcareous ooze can be deposited over
vast swathes of the deep ocean floor
.
Where are calcareous oozes found?
Calcareous ooze dominates
ocean sediments
. Organisms with calcium-based shells such as foraminifera are abundant and widely distributed throughout the world’s ocean basins –more so than silica-based organisms.
What is calcareous ooze and where does it accumulate on the seafloor?
Oozes are basically deposits of soft mud on the ocean floor. They form on
areas of the seafloor distant enough from land
so that the slow but steady deposition of dead microorganisms from overlying waters is not obscured by sediments washed from the land.
Where is calcareous ooze most likely to be found?
Where is calcareous ooze most likely to be found in surface sediments in the ocean? Calcareous ooze is most likely to be found in
relatively shallow areas with warm surface water
.
Where is calcareous ooze deposits and preserved?
The calcareous forams and coccoliths live at
the surface of the ocean
, not at the bottom. Furthermore, these organisms live virtually everywhere in the surface waters from the equator to the poles, so the answer to their preservation in deep water is not their distribution in surface waters.
How deep is the calcareous ooze?
The CCD is usually found at depths of
4 – 4.5 km
, although it is much shallower at the poles where the surface water is cold. Thus calcareous oozes will mostly be found in tropical or temperate waters less than about 4 km deep, such as along the mid-ocean ridge systems and atop seamounts and plateaus.
What is the difference between calcareous ooze and siliceous ooze?
The oozes are subdivided first into calcareous oozes (containing skeletons made of calcium carbonate) and siliceous oozes (containing skeletons made of silica) and then are divided again according to the predominant skeleton type.
What is calcareous ooze an example of?
Calcareous ooze is an example of
pelagic biogenous sediment
. The term pelagic means related to the ocean.
Where would you expect to find a high concentration of siliceous ooze?
Typically, siliceous ooze is present only in
regions of high biological surface water productivity
(such as the equatorial and polar belts and coastal upwelling areas), where depth of the seafloor is deeper than the CCD.
Why is calcareous ooze found near the ridge?
The distribution of modern calcareous ooze is generally found along mid-ocean ridges and in low-latitude ocean basins. The reason for this occurrence is that
most mid-ocean ridges are at a level higher than the CCD
and that low-latitude ocean basins are typically warm and often not as deep as the CCD.
Which is most likely to form siliceous ooze?
The proportion of lithogenous sediment decreases however as you move away from the continental shelf. In nutrient rich areas such as upwelling zones in the polar and equatorial regions,
silica-based organisms such as diatoms or radiolarians
will dominate, making the sediments more likely to be a siliceous-based ooze.
What conditions are needed in order for calcareous ooze to form?
Deeper in the ocean, changes in temperature, pressure, and water chemistry
cause calcareous tests to dissolve. At a certain depth, the tests dissolve faster than they accumulate, so calcareous oozes do not form below this depth; this depth is called the calcite compensation depth (CCD) (Figure 2).
What part of the oceans do not have calcareous ooze?
Calcium carbonate dissolves readily under pressure and in cold water, therefore
deeper ocean floors
will have less calcareous ooze.
Under what conditions is calcium carbonate more likely to dissolve?
Calcium carbonate is most likely to dissolve in
water
which has come from high latitudes and in which the carbon dioxide content has been increased by oxidative processes.
What three steps are required for calcareous ooze to exist below the CCD?
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
.
What is the most rapidly accumulating pelagic deposit on the seafloor?
Red clay
, also known as either brown clay or pelagic clay, accumulates in the deepest and most remote areas of the ocean. It covers 38% of the ocean floor and accumulates more slowly than any other sediment type, at only 0.1–0.5 cm/1000 yr.
