BEYOND THE THERMAL TRIGGER: INSIGHTS ON CAUSES AND EFFECTS OF THE PETM FROM NEW HIGH RESOLUTION, SUBMILLENNIAL RECORDS FROM THE NEW JERSEY COASTAL PLAIN

Paleoenvironmental reconstructions using expanded sedimentary records are vital to understanding triggers, mechanisms, and impacts of the Paleocene-Eocene thermal maximum (PETM), the largest rapid global warming event of the Cenozoic. Here we evaluate lead/lag relationships of the PETM warming and the attendant carbon isotopic excursion (CIE) from thick sections in the New Jersey Coastal Plain (NJCP) that contain expanded CIE records of up to 15 m. Auger cores drilled at Medford, NJ in 2016 provide the most updip shelf records among NJCP sites. Medford cores recovered a 60 cm-thick PETM onset interval, showing a gradual lithologic change from uppermost Paleocene glauconitic silts to lowermost Eocene kaolinitic clays. We measured stable isotopes in bulk sediments and several taxa of planktonic and benthic foraminifera that showed a steady 3.5‰ δ¹³C decrease through the onset interval. We also analyzed lipid biomarkers to estimate TEX₈₆ paleothermometer-based temperatures. Sampling intervals of 3-8 cm across the expanded PETM onset section at Medford, therefore, provided submillennial resolution according to various chronologies (Wright and Schaller, 2013; Zeebe et al., 2016). The new TEX₈₆-derived temperature and foraminiferal δ¹⁸O records showed no warming prior to the CIE onset at Medford, calling into question a temperature trigger for the carbon release suggested by previous studies of downdip NJCP sites and open ocean locations. This requires an alternative trigger for the cause of the PETM.