Warming and Carbon Injection at the Paleocene‐Eocene Boundary: Bayesian Modeling Supports Synchroneity

Abstract We evaluate lead‐lag relationships between warming associated with the Paleocene‐Eocene thermal maximum (PETM) and the attendant carbon isotope excursion (CIE) recorded in sedimentary archives from the mid‐Atlantic continental margin. Cores from the New Jersey coastal plain (NJCP) provide thick (up to 15 m), rapidly deposited shelf PETM sections recording a 6–8°C warming based on the TEX 86 paleothermometer. Updip cores from Medford, NJ provide the most expanded CIE onset, associated with a gradual lithologic change from uppermost Paleocene glauconitic sands to the lowermost Eocene kaolinitic Marlboro Clay. The relative thickness of these transitional sediments and the CIE onset allow for high‐resolution stable isotopic (bulk sediment, foraminifera, and organic carbon) and lipid biomarker analyses. The TEX H 86 ‐derived temperature records from Medford cores show no warming prior to the CIE onset, with the carbon isotopic decrease in phase with temperature. Previous studies of more downdip PETM sections on the NJCP suggested that warming preceded the CIE, consistent with a thermal trigger for carbon release. Re‐evaluation of published records and Bayesian analysis of TEX H 86 ‐derived temperature and δ 13 C from five NJCP sites do not indicate a statistically discernible lead or lag of carbon injection and warming. Though we can not preclude that a lead or lag exists, our analysis suggests that a synchronous CIE onset and warming is the most likely scenario on the NJ paleoshelf.