End-Cretaceous marine mass extinction not caused by productivity collapse

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doi: 10.1073/pnas.1110601109
Author(s): Alegret, Laia; Thomas, Ellen; Lohmann, Kyger C.
Author Affiliation(s): Primary:
Universidad Zaragoza, Departamento de Ciencias de la Tierra, Zaragoza, Spain
Yale University, United States
University of Michigan, United States
Volume Title: Proceedings of the National Academy of Sciences of the United States of America
Source: Proceedings of the National Academy of Sciences of the United States of America, 109(3), p.728-732. Publisher: National Academy of Sciences, Washington, DC, United States. ISSN: 0027-8424 CODEN: PNASA6
Note: In English. 48 refs.; illus., incl. sketch map
Summary: An asteroid impact at the end of the Cretaceous caused mass extinction, but extinction mechanisms are not well-understood. The collapse of sea surface to sea floor carbon isotope gradients has been interpreted as reflecting a global collapse of primary productivity (Strangelove Ocean) or export productivity (Living Ocean), which caused mass extinction higher in the marine food chain. Phytoplankton-dependent benthic foraminifera on the deep-sea floor, however, did not suffer significant extinction, suggesting that export productivity persisted at a level sufficient to support their populations. We compare benthic foraminiferal records with benthic and bulk stable carbon isotope records from the Pacific, Southeast Atlantic, and Southern Oceans. We conclude that end-Cretaceous decrease in export productivity was moderate, regional, and insufficient to explain marine mass extinction. A transient episode of surface ocean acidification may have been the main cause of extinction of calcifying plankton and ammonites, and recovery of productivity may have been as fast in the oceans as on land.
Year of Publication: 2012
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Acidification; Assemblages; Atlantic Ocean; Benthic taxa; C-13/C-12; Carbon; Carbon cycle; Causes; Cenozoic; Cretaceous; DSDP Site 465; Deep Sea Drilling Project; Ecosystems; Foraminifera; Geochemical cycle; Hess Rise; IPOD; Impacts; Invertebrata; Isotope ratios; Isotopes; K-T boundary; Leg 113; Leg 198; Leg 208; Leg 62; Lower Paleocene; Mass extinctions; Maud Rise; Mechanism; Mesozoic; Microfossils; Morphology; North Pacific; Northwest Pacific; O-18/O-16; ODP Site 1210; ODP Site 1262; ODP Site 690; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleo-oceanography; Paleocene; Paleoecology; Paleogene; Pelagic environment; Photochemistry; Photosynthesis; Productivity; Protista; Shatsky Rise; South Atlantic; Southern Ocean; Stable isotopes; Stratigraphic boundary; Tertiary; Upper Cretaceous; Walvis Ridge; Weddell Sea; West Pacific
Coordinates: N321300 N321300 E1581600 E1581600
S271100 S271100 E0013500 E0013400
S650938 S650937 E0011218 E0011218
N334914 N334914 E1785508 E1785508
Record ID: 2014035875
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