Plot the distribution of various oozes using information from sediment maps.
- Describe the characteristics of different types of seafloor sediments and oozes.
- Predict distribution of calcareous and siliceous oozes.
- Compare and discuss locations of sediments and oozes.
Terrigenous, Biogenous, Hydrogenous, Cosmogenous, Calcareous ooze, Siliceous ooze, Foraminifera, Diatoms, adiolaria, Carbonate compensation depth
Just as ocean beaches display a variety of sediment types, the ocean
floor may be made of sand, rock, remains of living organi
Just as ocean
beaches display a variety of sediment types, the ocean floor may be made of
sand, rock, remains of living organisms, or other material. The grains and
particles that make up the seafloor sediments are classified by their size and
their point of origin. Sediments can come from land (terrigenous), from living
organisms (biogenous), from chemical reactions in the water column
(hydrogenous), and even from outer space (cosmogenous).
sediments dominate the edges of the ocean basins, close to land where they
originated. As you move deeper into the ocean basins, biogenous sediments begin
to dominate. Biogenous sediments can consist of waste products or remains of
organisms, including those of microscopic phytoplankton and zooplankton. When
skeletal remains of microscopic organisms make up more than 30% of the
sediment, it is called "ooze."
There are two
types of oozes, calcareous ooze and siliceous ooze. Calcareous ooze, the most
abundant of all biogenous sediments, comes from organisms whose shells (also
called tests) are calcium-based, such as those of foraminifera,
a type of zooplankton. Foraminifera are one of the most abundant types of
zooplankton and are widely distributed throughout the surface of the world's
are made up of the remains of diatoms, a microscopic phytoplankton, and radiolaria, a microscopic zooplankton. Diatoms are one of
the most important primary producers in the ocean. Because they are primary
producers, diatoms are found in nutrient-rich areas of the ocean especially in
areas of upwelling like the polar seas. As you move from continental shelf to
open ocean areas, the number of diatoms present decreases. Radiolarians, the other source of siliceous ooze, feed on
phytoplankton and thus are also more abundant in nutrient-rich water. However,
radiolaria favor the equatorial upwelling zones as opposed to the polar
that affects where biogenous sediments will occur is the depth of the ocean
floor. Calcium carbonate dissolves readily under pressure and in cold water,
therefore deeper ocean floors will have less calcareous ooze. At a depth of
about 5 km, the rate of dissolution (how quickly calcium carbonate dissolves)
is faster than the rate at which calcium shells are raining down from above.
This depth is called the carbonate compensation depth or CCD.
you've learned about the distribution of diatoms, radiolaria and foraminifera
and about the carbonate compensation depth, predict where you think you would
find calcareous and siliceous oozes. Print a global map,
and mark your predictions on it.
the IUPUI's Introduction to Oceanography: Marine Sediment Map. This map shows the general location of
- Were your predictions close to where
calcareous and siliceous oozes actually occur?
- How does your map compare with the
sediment distribution map?
- Which type of ooze dominates the ocean
sediments, calcareous or siliceous? Why?
- What parts of the oceans do not have
calcareous ooze? What might be some reasons for this? (Hint: depth,
distribution of organisms)
- Where are large deposits of siliceous
diatom ooze? Are these deposits mostly near the edges of continents or in
the middle of the ocean basins? Why? (Hint: areas of upwelling/high
- Where do you see large deposits of
siliceous radiolarian ooze? Why?