THE IMPACT OF SAMPLING IN BURROWS ON GEOCHEMICAL RECORDS ACROSS THE PALEOCENE EOCENE THERMAL MAXIMUM

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 ichnofabric index from International Ocean Discovery Program (IODP) sites from all over the globe. We find major differences in the intensity of bioturbation between the different locations, with cessation of bioturbation found at some of the sites. At three Pacific sites, we utilize a novel burrow-specific sampling technique to determine the impact of bioturbating organisms in bulk geochemical records. Our analysis shows that with a decrease in bioturbation intensity, there is an increase in isotopic difference between samples from inside and directly outside of burrows.