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Marine biological consequences of the Cretaceous/Tertiary mass Extinction

Steve D’Hondt
University of Rhode Island

Wednesday, March 22, 2000
3:00 p.m.—Pacific Forum

The 65-Ma Cretaceous/Tertiary (K/T) mass extinction was one of the largest biological catastrophes of all time. Studies of Ocean Drilling Program cores show that the flux of organic carbon to the deep sea and the accumulation of planktonic carbonates in deep-sea sediments drastically declined at the time of mass extinction. The deep-sea organic flux did not fully recover for more than three million years. Deep-sea carbonate accumulation did not recover for four million years. These long delays in geochemical and sedimentological recovery indicate that global biogeochemical cycles and open-ocean ecological structure were altered for more than three million years by the K/T extinction event. These biological consequences may have changed ocean chemistry and climate for millions of years. Oceanic alkalinity, atmospheric concentrations of carbon dioxide, and the oceanic residence times and concentrations of calcium, magnesium, and a host of trace elements are all affected by marine fluxes of biologically fixed carbon and/or carbonate minerals. Final ecological and biogeochemical recovery may have required the evolution of new species at key trophic levels to replace those lost during the mass extinction.

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 Last updated: December 19, 2000