EXPANDED RECORD OF THE PALEOCENE-EOCENE THERMAL MAXIMUM ONSET IN THE APPALACHIAN AMAZON

Expanded Paleocene-Eocene Thermal Maximum (PETM) sections recording the attendant carbon isotope excursion (CIE) (up to 15 m thick) make the New Jersey Coastal Plain (NJCP) an excellent locale for high-resolution analyses. The rapid onset of the PETM has made it an attractive analog for modern warming, though the rate of the initiation ranges from millennial-scale (~ 4 kyr for 2000+ GtC e.g. Zebee et al., 2016) to nearly instantaneous (e.g. Wright and Schaller, 2013). New cores from the updip Medford auger project provide a proximal anchor for building a cross-shelf PETM depositional model. Multiple records at Medford preserve the CIE onset and the lower portion of the CIE “body/core” through a 2 m thick section; the CIE onset (< 4 kyr) occurs in a 60 cm interval indicating rapid sedimentation rates (> 15 cm/kyr). We use δ¹³C, percent CaCO₃, and percent sand fraction to correlate Medford with records along a paleoslope dip transect (ODP Leg 174AX Wilson Lake, Millville, and Bass River), showing that different parts of the CIE were preserved and expanded updip (the oldest part) compared to down dip (the youngest part). This pattern can be best explained by the progradation of mud clinoforms, similar to those observed on the modern Amazon continental shelf. Our data indicate rapid sedimentation that we explain by fluid mud driven deposition on clinoform foresets, similar to the modern Amazon. Despite the massive input of muds from this “Appalachian Amazon”, isotope and faunal data indicate near normal salinities, suggesting episodic transport from these hyperpycnal flows with intervening normal marine sedimentation. Our subaqueous-clinoform delta model explains the variability of the CIE records across the NJCP and ties this isotopic trend into the regional lithology, providing a framework for successive PETM studies in the region.