Upper Cretaceous African climate development and implications for the marine carbon cycle

Beckmann, B., Flögel, Sascha, Hofmann, P., Schulz, M. and Wagner, T. (2005) Upper Cretaceous African climate development and implications for the marine carbon cycle Nature, 437 . pp. 241-244. DOI 10.1038/nature03976.

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The tropics have been suggested as the drivers of global ocean and atmosphere circulation and biogeochemical cycling during the extreme warmth of the Cretaceous period1, 2; but the links between orbital forcing, freshwater runoff and the biogeochemistry of continental margins in extreme greenhouse conditions are not fully understood. Here we present Cretaceous records of geochemical tracers for freshwater runoff obtained from a sediment core off the Ivory Coast that indicate that alternating periods of arid and humid African climate were driven by orbital precession. Our simulations of the precession-driven patterns of river discharge with a global climate model suggest that ocean anoxia and black shale sedimentation were directly caused by high river discharge, and occurred specifically when the northern equinox coincided with perihelion (the minimum distance between the Sun and the Earth). We conclude that, in a warm climate, the oceans off tropical continental margins respond rapidly and sensitively to even modest changes in river discharge.

Document Type: Article
Keywords: Africa, climate, upper Cretaceous, marine carbon cycle, ODP Leg 159, Ivory Coast
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
DOI etc.: 10.1038/nature03976
ISSN: 0028-0836
Projects: ODP
Date Deposited: 03 Dec 2008 16:50
Last Modified: 10 Mar 2017 11:04
URI: http://eprints.uni-kiel.de/id/eprint/681

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