Paleo-redox Reconstructions Across the Paleocene-Eocene Thermal Maximum
Abstract
Manganese and Uranium enrichment factors (EF) relative to crustal averages from nine Deep Sea Drilling Project and Ocean Drilling Program sites are presented to examine paleo-redox changes across the Paleocene-Eocene Thermal Maximum (PETM). We use geochemical tracers to infer the bottom-water oxygen concentrations during this abrupt warming event. Determining redox changes will test the hypothesis that low oxygen concentrations caused the benthic foraminifera extinction event as well as contribute to our understanding of where the source of isotopically light carbon was released. The comparison of Mn EF before and after a reductive cleaning procedure allows us to determine the presence of Mn-oxides or Mn-carbonates. Mn EF representing Mn oxides and no U EF suggest oxygenated bottom-waters. Mn-carbonates and U EF suggest reducing conditions and an early diagenetic phase. We will present our results relative to the orbitally tuned age model of Site 1263. Mn EF range from 1-9 in Atlantic sites, 1-35 Southern Ocean sites, and 5-400 in Pacific sites. U EF range from 1-5 in Atlantic sites, 1-90 in Southern Ocean sites, and crustal averages EF =1 in Pacific sites. Our initial results indicate reducing conditions prior, during, and in the recovery of the PETM at intermediate depth sites in the Atlantic and Southern Ocean while the Pacific sites remain oxygenated. Reducing bottom- water conditions in the Atlantic and Southern Ocean may have contributed to the benthic foraminifera extinction event. Release of methane in the oceans oxidizes to carbon dioxide, depleting bottom-water oxygen concentrations. Because our sites in the Atlantic have the most reducing bottom-waters, we suggest the Atlantic Ocean could have been the source for isotopically light carbon release during the PETM.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMPP32A..05C
- Keywords:
-
- 1050 Marine geochemistry (4835;
- 4845;
- 4850);
- 1065 Major and trace element geochemistry;
- 4900 PALEOCEANOGRAPHY (0473;
- 3344);
- 4924 Geochemical tracers;
- 4948 Paleocene/Eocene thermal maximum