CHRONOSTRATIGRAPHIC FRAMEWORK AND COMPOSITE SECTION COMPILATION OF UPPER PALEOCENE AND LOWER EOCENE SEDIMENTS FROM THE SALISBURY EMBAYMENT, USA (Invited Presentation)

Upper Paleocene and lower Eocene sediments from the Salisbury Embayment of New Jersey and Maryland have recently been the focus of numerous studies centered on the Paleocene-Eocene Thermal Maximum (PETM) and subsequent Eocene hyperthermal events. Research has focused on the timing and rates of sediment input and biotic response due to changing paleoclimatic conditions. However, Atlantic Coastal Plain sediments rarely reflect continuous deposition and are often truncated due to erosion, current activity, and faulting. These factors can affect correlation among cores and also our ability to provide meaningful estimates of sedimentation rates through time.

Using data from the Knapps Narrows (KN), Howards Tract 1&2 (HT), and South Dover Bridge (SDB) cores on the Eastern Shore of Maryland (Talbot and Dorchester Counties), we present a preliminary composite section that spans the upper Paleocene Aquia Formation to a lower Eocene unnamed unit equivalent in age to the oldest part of the lower to middle Eocene Shark River Formation of New Jersey. Paleomagnetic data place these units in Chron 24r through the lower part of Chron 21r and biostratigraphy suggests concordant placement in the upper part of calcareous nannofossil Zone NP9a through the lower part of Zone NP14. Numerous unconformities are present and differ from core to core. The entire record of the PETM (Marlboro Clay) is missing from KN, which instead has a greatly expanded lower Eocene (Nanjemoy Formation) section. All of upper NP11 and part of lower NP12 are truncated in HT and an unconformity is present at the top of the Nanjemoy Formation in both HT and SDB. Negative shifts in bulk δ¹³C isotopes occur at the base of the PETM (SDB and HT), in lower NP10 (Chron 24r; HT and KN), in upper NP10/lower NP11 (Chron 24r; KN), and in upper NP11 (Chron 24n; SDB and KN). The three early Eocene isotope shifts most likely correlate to the ETM2, H2, and I1 hyperthermal events, respectively. By combining all available data (magnetostratigraphy, biostratigraphy, geochemistry, and lithostratigraphy), we are able to produce a composite and continuous reference section that spans the latest Paleocene through early Eocene and can be used for correlation of sediments across the Salisbury Embayment.