PALEOCENE SEQUENCE STRATIGRAPHY ON THE NEW JERSEY COASTAL PLAIN

We used benthic foraminifers and integrated stratigraphic studies to assess water-depth changes of four Paleocene sequences identified in coreholes at Bass River, Ancora, and Millville, NJ (ODP Leg 174AX). These sequences are located in the Vincentown Formation (glauconitic silts and clays) and the underlying Hornerstown Formation (glauconitic clay). Sequence boundaries were identified by hiatuses, unconformities and variations in benthic foraminiferal biofacies. Factor analysis was performed on benthic foraminifers at each corehole to identify foraminiferal assemblages and aid sequence boundary identification and paleoenvironment interpretation. We identified three distinct benthic foraminiferal assemblages and estimated their associated paleowater depths. Gavelinella beccariformis parvula is a middle-outer shelf species that dominated the first assemblage. The second assemblage represents an outer shelf environment dominated by Pulsiphonina prima and Anomalinoides acuta. Tappanina selmensis is an opportunistic species that dominated the third assemblage. We use faunal metrics (e.g., % planktonic foraminifera and census data) and a paleoslope model to interpret the paleowater depth of each assemblage. Paleowater depths were ~80 m during the early Paleocene, with a maximum water depth of 100 m at Bass River. A long-term water depth shallowing of ~20 m is observed through the middle-late Paleocene toward the Carbon Isotope Excursion (CIE). The shallowing trend reverses at the CIE, with a water depth increase of ~80 m. Location, identification and paleoenvironments of these sequences are consistent with previous New Jersey coastal plain studies at Island Beach (ODP Leg 150X) and DSDP Sites 605, 612, and 613. We compare the ages of Paleocene sequence boundaries in NJ with global oxygen isotope records. Oxygen isotope increases at 59.5 Ma and 64.6 Ma may correlate with sequence boundaries in NJ, potentially linking sea level falls with glacioeustatic lowering.