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Chalk is so common in Cretaceous marine beds that the Cretaceous Period was named for these deposits. The name Cretaceous was derived from Latin creta, meaning chalk. [10] Some deposits of chalk were formed after the Cretaceous. [11] The Chalk Group is a European stratigraphic unit deposited during the late Cretaceous Period.
Marine biogenic calcification is the production of calcium carbonate by organisms in the global ocean.. Marine biogenic calcification is the biologically mediated process by which marine organisms produce and deposit calcium carbonate minerals to form skeletal structures or hard tissues.
Water is the medium of the oceans, the medium which carries all the substances and elements involved in the marine biogeochemical cycles. Water as found in nature almost always includes dissolved substances, so water has been described as the "universal solvent" for its ability to dissolve so many substances.
Marine sediment, or ocean sediment, or seafloor sediment, are deposits of insoluble particles that have accumulated on the seafloor.These particles either have their origins in soil and rocks and have been transported from the land to the sea, mainly by rivers but also by dust carried by wind and by the flow of glaciers into the sea, or they are biogenic deposits from marine organisms or from ...
The chalk of the White Cliffs of Dover is almost entirely formed from fossil skeleton remains , biomineralized by planktonic microorganisms (coccolithophores). Biomineralization plays significant global roles terraforming the planet, as well as in biogeochemical cycles [ 17 ] and as a carbon sink .
The coccolithophores lived in the upper part of the water column. When they died, the microscopic calcium carbonate plates, which formed their shells settled downward through the ocean water and accumulated on the ocean bottom to form a thick layer of calcareous ooze, which eventually became the Chalk Group.
The putative galloanseran bird Austinornis lentus has been found in the Austin Chalk. [2] [3] The general absence of dinosaurs is a reflection of the Austin limestone being marine in origin, primarily composed of microscopic shell fragments from floating sea organisms known as "coccolithophores" (the same organisms that contributed to the White Cliffs of Dover, on the south coast of England). [4]
It is the part of the broader oceanic carbon cycle responsible for the cycling of organic matter formed mainly by phytoplankton during photosynthesis (soft-tissue pump), as well as the cycling of calcium carbonate (CaCO 3) formed into shells by certain organisms such as plankton and mollusks (carbonate pump).