UTILIZING BIOTURBATION TO CONSTRAIN PALEOCENE-EOCENE THERMAL MAXIMUM CARBON CYCLING IN THE PACIFIC

The Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) was an abrupt period of greenhouse warming during which thousands of gigatons of isotopically depleted carbon were added to the atmosphere over a few thousand years, leading to a global negative carbon isotope excursion (CIE) and carbonate dissolution. Deep sea sediment cores are the primary source of information for these changes in climate and global carbon cycling, but these are subject to alteration through animal activity within the sediments after deposition (bioturbation). One of the great challenges in paleoclimate research is identifying where and how the sediment record has been distorted through bioturbation or erased through dissolution. Across the PETM, differences in bioturbation intensity between ocean sites can provide unique insight into the benthic environment, and may correlate to spatial patterns in carbonate dissolution, changes in ocean oxygenation, CIE magnitude, and event recovery timescale. Here, we analyze the sedimentology and bioturbation from Deep Sea Drilling Project Site 577 and Ocean Drilling Program (ODP) Sites 865, 1209, 1210, 1220, and 1221. We find major differences in the intensity of bioturbation between the different locations, with cessation of bioturbation found at four of the six sites. With dramatic changes in lithology, we are able to identify and measure a variety of traces fossils such as Chondrites and Planolites throughout the recovery period. We then compare bioturbation intensity with wt% CaCO₃ and bulk carbon isotopes from these sites. Our analyses of the cores show a lithology-dependent response in bioturbation, and a delayed cessation relative to the carbon isotope excursion.