DISSECTING THE PALEOCENE-EOCENE BOUNDARY SEQUENCES ALONG THE NEW JERSEY COASTAL PLAIN

The Paleocene-Eocene thermal maximum (PETM) is the most extreme of a series of short episodes of global warming. Its sedimentary and biotic expression at shelf-depths in the New Jersey (NJ) Coastal Plain has only recently been explored intensively, although a unit of silty clays, unusual for NJ where glauconitic sands are common, has long been recognized (Olsson and Wise 1987). This unit is now correlated to the Marlboro Clay in Maryland and Virginia, and isotopic and biotic data unequivocally show that it was deposited during the PETM. The exact part of PETM-time represented in the sediments remains unclear, however, with a widespread unconformity truncating its upper part. We use high-resolution stable isotope and benthic foraminiferal assemblage records (with published isotope, nannofossil and dinoflagellates records) to correlate in detail between 4 NJ cores along an onshore-offshore transect: Clayton, Wilson Lake, Ancora and Bass River. The onset of the PETM at the base of the abrupt carbon isotopic excursion (CIE) occurs at the transition from glauconitic sand to silty clay, where opportunistic benthic foraminiferal taxa become abundant, indicating dysoxic conditions (Tappanina selmensis, Pulsiphonina prima and Anomalinoides acutus). Transitional faunas occur in the more onshore sites, but the transition is condensed further offshore. Diversity trends indicate a steady recovery during the PETM, as reflected in the gradual increase in abundance of less opportunistic taxa (Spiroplectinella and Pseudouvigerina spp.). Stable isotope records show that all sites contain the CIE “core”, but its upper part is truncated at the more onshore sites, so that < 70 kyr is reflected in the sediment. Stable isotope records indicate that in more offshore sites the later parts of the PETM are represented, including parts of the recovery phase (Bass River: recovery phase I; Ancora: recovery phases I and II). During this recovery phase, oxic bottom water conditions became re-established (Bulimina callahani). Our proposed stratigraphic framework enables development of a better age model, thus correlation between US coastal plain sites as well as with the global record, improved estimates of accumulation rates, and construction of a composite sequence.