- Also called:
- biogenic sediment
biogenic ooze
-
What is biogenic ooze?
Biogenic ooze is pelagic sediment on the sea floor with at least 30% skeletal material from dead microscopic organisms.
These remains are either:
* calcium carbonate in the form of the mineral calcite or aragonite
* opal (amorphous, hydrated silica)The distribution of biogenic oozes depends on the supply of skeletal material, how quickly the skeletons dissolve, and how diluted they are by other sediment types like turbidites or clays.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How does biogenic ooze form in the ocean?
Biogenic ooze forms in the deep sea from the accumulation of at least 30% skeletal remains of microscopic floating organisms. These remains are either calcareous (calcium carbonate) or siliceous (silica).
Calcareous oozes come from microorganisms like foraminiferans and coccoliths, while siliceous oozes are composed of diatoms, radiolarians, and other organisms. The distribution of biogenic oozes relies on the supply of skeletal material, how well the skeletons dissolve, and how diluted they are by other sediment types.
4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What kinds of tiny organisms contribute to biogenic ooze?
Biogenic ooze is a pelagic sediment on the deep sea floor with at least 30% skeletal remains of microscopic floating organisms. These organisms include foraminiferans, which leave behind calcareous tests, and diatoms and radiolarians, which leave behind siliceous skeletons. Coccoliths, microscopic carbonate plates coating some marine algae and protozoa, also contribute to biogenic ooze.
4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Where on the ocean floor is biogenic ooze most commonly found?
Biogenic oozes, pelagic sediments with over 30% skeletal material, are either calcareous (carbonate) or siliceous. Their distribution hinges on skeletal material supply, skeleton dissolution, and dilution from other sediments.
Carbonate oozes dominate the deep Atlantic seafloor above 4,500 meters, covering about half the world's seafloor. Siliceous oozes are most common in the Pacific and around Antarctica. High primary productivity at the Equator, in coastal upwelling zones, and near Antarctica supports siliceous ooze deposition. Radiolarian oozes are common near the Equator in the Pacific, while diatom oozes prevail at high latitudes, especially around Antarctica.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What are the main types of biogenic ooze, and how are they different?
Biogenic oozes are pelagic sediments with at least 30% skeletal remains of marine organisms and are divided into calcareous and siliceous types.
-
Calcareous Oozes These contain calcium carbonate, often as calcite or aragonite, from microorganisms like foraminifera and coccoliths. They are common above 4,500 meters, especially in the Atlantic, as carbonate dissolves in deeper water.
-
Siliceous Oozes Made of opal, a hydrated silica, from diatoms, radiolarians, and siliceous sponges, these are indicators of high productivity. They are typical around Antarctica and near the Equator in the Pacific.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
-
How do scientists use biogenic ooze to learn about Earth’s history?
Scientists analyze biogenic ooze, a deep-sea sediment with at least 30% skeletal remains of tiny floating organisms, to understand Earth's history. The distribution of these oozes is affected by the supply of skeletal material, how the skeletons dissolve, and dilution from other sediment types.
Analyzing the skeletal remains of microfossils within the ooze helps determine the temperature and isotopic composition of the seawater at the time the organisms lived. The marine oxygen isotope record from these microfossils provides a continuous record of past glaciations and interglaciations, serving as a standard for correlating terrestrial records and understanding long-term climatic changes.
8 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
biogenic ooze, any pelagic sediment that contains more than 30 percent skeletal material. These sediments can be made up of either carbonate (or calcareous) ooze or siliceous ooze. The skeletal material in carbonate oozes is calcium carbonate usually in the form of the mineral calcite but sometimes aragonite. The most common contributors to the skeletal debris are such microorganisms as foraminiferans and coccoliths, microscopic carbonate plates that coat certain species of marine algae and protozoa. Siliceous oozes are composed of opal (amorphous, hydrated silica) that forms the skeleton of various microorganisms, including diatoms, radiolarians, siliceous sponges, and silicoflagellates. The distribution of biogenic oozes depends mainly on the supply of skeletal material, dissolution of the skeletons, and dilution by other sediment types, such as turbidites or clays.
Primary productivity, the production of organic substances through photosynthesis and chemosynthesis, in the ocean surface waters controls the supply of material to a large extent. Productivity is high at the Equator and in zones of coastal upwelling and also where oceanic divergences occur near Antarctica. Productivity is lowest in the central areas of the oceans (the gyres) in both hemispheres. Siliceous oozes are more reliable indicators of high productivity than carbonate oozes. This is because silica dissolves quickly in surface waters and carbonate dissolves in deep water; hence, high surface productivity is required to supply siliceous skeletons to the ocean floor. Carbonate oozes dominate the deep Atlantic seafloor, while siliceous oozes are most common in the Pacific; the floor of the Indian Ocean is covered by a combination of the two.
Carbonate oozes cover about half of the world’s seafloor. They are present chiefly above a depth of 4,500 metres (about 14,800 feet); below that they dissolve quickly. This depth is named the Calcite Compensation Depth (or CCD). It represents the level at which the rate of carbonate accumulation equals the rate of carbonate dissolution. In the Atlantic basin the CCD is 500 metres (about 1,600 feet) deeper than in the Pacific basin, reflecting both a high rate of supply and low rate of dissolution in comparison to the Pacific. The input of carbonate to the ocean is through rivers and deep-sea hydrothermal vents. Variation in input, productivity, and dissolution rates in the geologic past have caused the CCD to vary over 2,000 metres (about 6,600 feet). The CCD intersects the flanks of the world’s oceanic ridges, and as a result these are mostly blanketed by carbonate oozes.
" height="20" alt="HEW Logo">
Siliceous oozes predominate in two places in the oceans: around Antarctica and a few degrees of latitude north and south of the Equator. At high latitudes the oozes include mostly the shells of diatoms. South of the Antarctic Convergence diatom oozes dominate the seafloor sediment cover and mix with glacial marine sediments closer to the continent. Seventy-five percent of all the oceans’ silica supply is being deposited in the area surrounding Antarctica. Radiolarian oozes are more common near the Equator in the Pacific. Here, both siliceous oozes and calcareous oozes occur, but carbonate deposition dominates the region immediately near the Equator. Siliceous oozes bracket the carbonate belt and blend with pelagic clays farther north and south. Because siliceous skeletons dissolve so quickly in seawater, only the more robust skeletal remains are found in the siliceous oozes. Thus, fossils of this kind are not completely representative of the organisms living in the waters above.