2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 314-5
Presentation Time: 9:00 AM-6:30 PM


TRAMPUSH, Sheila and HAJEK, Elizabeth, Department of Geosciences, The Pennsylvania State University, University Park, PA 16802, smt254@psu.edu

Understanding the impact of the Paleocene-Eocene Thermal Maximum (PETM) on the North American mid-Atlantic shelf is important for evaluating how sedimentary and biological systems on continental shelves respond to abrupt warming. While specific biological and geochemical responses have been extensively studied in this region, a comprehensive picture of sedimentary environments and depositional processes throughout the PETM remains elusive. Constraining these changes in sedimentary dynamics is necessary to both assess the sensitivity and resilience of North American shelf environments and to evaluate the completeness and fidelity of the PETM record in general. In order to improve paleoenvironmental and sedimentary-process interpretations of the PETM mid-Atlantic shelf, we analyzed 16 cores drilled in New Jersey, Maryland, and Virginia. First, we evaluated the precision of previously published environmental interpretations for before, during, and after the PETM carbon isotope excursion based on the strength of the evidence (e.g., water depths constrained by specific fossil assemblages are stronger than depth-interpretations based solely on grain size). We then constructed a depositional model that accounts for both the available environmental indicators and state-of-the-art sedimentary-process understanding. We used the depositional model to create a regional correlation between all 16 cores and evaluated depositional variability within different environments at a range of scales. Despite eustatic sea-level rise during the PETM, the large-scale sedimentary pattern through the interval can be explained by a substantial increase in fine-grained sediment (silt and clay) supply to the mid-Atlantic margin resulting in clastic progradation. Additionally, smaller-scale heterogeneities indicate that sedimentary responses varied regionally across the shelf.