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

Paper No. 210-41
Presentation Time: 9:00 AM-6:30 PM


SPIVEY, Whittney E., U.S. Geological Survey, Reston, VA 20192; Department of Geology and Environmental Science, James Madison University, 395 S. High Street, Harrisonburg, VA 22807 and ROBINSON, Marci M., Eastern Geology and Paleoclimate Science Center, U.S. Geological Survey, MS 926A, 12201 Sunrise Valley Drive, Reston, VA 20192, wspivey@usgs.gov

The Paleocene-Eocene boundary is marked by a sudden and rapid negative Carbon Isotope Excursion (CIE) with an associated extreme warming event known as the Paleocene-Eocene Thermal Maximum (PETM; ~55.6 Ma). The Benthic Extinction Event in the deep sea and foraminiferal assemblage turnover events in neritic settings across the Paleocene-Eocene boundary were direct responses to this climatic event. The Atlantic Coastal Plain, from New Jersey to Georgia, has a relatively continuous record of the PETM in shelf sediments. In 2007, the U.S. Geological Survey drilled the South Dover Bridge core in Talbot County, Maryland. This site has an expanded PETM section including the latest Paleocene Aquia Formation and 51.3 ft. of the early Eocene Marlboro Clay. A relatively small (-2‰) pre-onset excursion (POE) within the Aquia Formation precedes the larger (-4‰) Paleocene-Eocene CIE onset that coincides with the Aquia Formation-Marlboro Clay contact. Both the POE and CIE are marked by the increase of agglutinated benthic foraminifers, not only relative to calcareous benthic foraminifers but also in number of specimens per gram. Between the two events, we recorded an agglutinated assemblage turnover. We will discuss what these changes mean in terms of dissolution, accumulation rate, paleodepth and benthic ecology.