233-6 Consequences of the Cretaceous/Paleogene mass extinction for marine ecosystems

Session: Impact Cratering and the Evolution of Life

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One of the greatest mass extinctions in Earth’s history occurred at the end of the Cretaceous era, 66 million years (Myr) ago. Considerable evidence indicates that the impact of a large asteroid or comet was the ultimate cause of this extraordinary event. At the time of mass extinction, the organic flux to the deep sea collapsed, and production of calcium carbonate by marine plankton radically declined. The open-ocean carbon cycle did not fully recover for a few million years. The drastic decline and long lag in final recovery of these processes are most simply explained as consequences of open-ocean ecosystem alteration by the mass extinction. Diverse studies indicate that primary productivity was at least locally high, community taxonomic composition varied considerably from one oceanic region to another, and organic export to shallow water depths at least locally recovered early during this long period of globally altered carbon cycling. Given these complexities, marine biological productivity probably recovered quickly after the impact, but full marine carbon-cycle recovery was delayed until open-ocean ecosystem structure crossed a critical recovery threshold. Once that happened, the biogeochemical recovery may in turn have created new evolutionary opportunities for a diverse array of marine organisms.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11156

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