Spatial and Temporal Patterns in Petrogenic Organic Carbon Mobilization During the Paleocene‐Eocene Thermal Maximum
Emily H. Hollingsworth, Felix J. Elling, Marcus P. S. Badger, Richard D. Pancost, Alexander J. Dickson, Rhian L. Rees-Owen, Nina M. Papadomanolaki, Ann Pearson, Appy Sluijs, Katherine H. Freeman, Allison A. Baczynski, Gavin L. Foster, Jessica H. Whiteside, Gordon N. Inglis
Abstract
Abstract The Paleocene‐Eocene Thermal Maximum (PETM) was a transient global warming event and is recognized in the geologic record by a prolonged negative carbon isotope excursion (CIE). The onset of the CIE was due to a rapid influx of 13 C‐depleted carbon into the ocean‐atmosphere system. However, the mechanisms required to sustain the negative CIE remains unclear. Enhanced mobilization and oxidation of petrogenic organic carbon (OC petro ) has been invoked to explain elevated atmospheric carbon dioxide concentrations after the onset of the CIE. However, existing evidence is limited to the mid‐latitudes and subtropics. Here, we determine whether: (a) enhanced mobilization and subsequent burial of OC petro in marine sediments was a global phenomenon; and (b) whether it occurred throughout the PETM. To achieve this, we utilize a lipid biomarker approach to trace and quantify OC petro burial in a global compilation of PETM‐aged shallow marine sites ( n = 7, including five new sites). Our results confirm that OC petro mass accumulation rates (MARs) increased within the subtropics and mid‐latitudes during the PETM, consistent with evidence of higher physical erosion rates and intense episodic rainfall events. High‐latitude sites do not exhibit drastic changes in the source of organic carbon during the PETM and OC petro MARs increase slightly or remain stable, perhaps due a more stable hydrological regime. Crucially, we also demonstrate that OC petro MARs remained elevated during the recovery phase of the PETM. Although OC petro oxidation was likely an important positive feedback mechanism throughout the PETM, we show that this feedback was both spatially and temporally variable.