HR: 0800h
AN: PP41A-0582    [Abstracts]
TI: Causes of the marine productivity and oxygen changes associated with the Permian - Triassic boundary: A reevaluation with general ocean circulation models
AU: * Winguth, A
EM: amwinguth@wisc.edu
AF: University of Wisconsin-Madison, Center for Climatic Research 1225 W. Dayton St, Madison, Wi 53706 United States
AU: Maier-Reimer, E
EM: maier-reimer@dkrz.de
AF: Max-Planck-Institute for Meteorology, Bundesstr. 55, Hamburg, 20146 Germany
AB: Widespread anoxic and dysoxic deposition in marine sediments has been associated with a stagnant ocean at the Permian-Triassic (P-Tr) boundary. This P-Tr boundary is also associated with one of the largest mass extinctions of species in the Paleozoic. Here we review recent three-dimensional numerical model studies that investigated possible circulation patterns at the P-Tr boundary. In addition, we conduct new sensitivity experiments with a coupled ocean-atmosphere model of intermediate complexity including marine chemistry to study changes of the deep sea oxygen distribution associated with 1) a significant change in the hydrological cycle and 2) a massive release of methane gas hydrates from marine sediments. Freshening of sea surface water masses in the magnitude of the Permian deglaciation produces a significant local minimum in oxygen in the eastern tropical Panthalassa ocean at intermediate depth and at the sea floor. The methane release experiment simulates a strong increase in sea surface temperature (about 7 K) and a vigorous deep sea circulation. In contrast to the conclusions drawn from previous studies, this reanalysis of the ocean circulation at the P-Tr boundary favors a strong ventilation in most parts of the deep sea. Thus, a significant change in the oceanic carbon inventories and a reorganization of the marine productivity associated with a stronger biological pump may be required to explain the anoxic sedimentary deposits.
UR: http://drake.aos.wisc.edu/~winguth/Papers/Papers1.html
DE: 4805 Biogeochemical cycles (1615)
DE: 4267 Paleoceanography
DE: 4532 General circulation
DE: 3099 General or miscellaneous
DE: 0330 Geochemical cycles
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting