GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 194-19
Presentation Time: 9:00 AM-6:30 PM


BROUSSARD, Joshua, Department of Geosciences, Mississippi State University, P.O. Box 5448, Mississippi State, MS 39762, CLARY, Renee M., Geosciences, Mississippi State University, Mississippi State, MS 39762 and PHILLIPS, George E., Paleontology, Mississippi Museum of Natural Science, 2148 Riverside Drive, Jackson, MS 39202-1353

Northeast Mississippi exposes the Cretaceous-Paleogene (K-Pg) boundary at multiple locales. These contacts are comprised of the Late Cretaceous (Maastrichtian) Prairie Bluff chalk or Ripley Formation, uncomfortably overlain by the Early Paleocene (Danian) Clayton Formation. The Clayton Formation is notable for being the first chronostratigraphic unit following the Cretaceous-Paleogene extinction in the southeastern United States. The Clayton Formation is a marine unit containing several fossiliferous layers of limestone, clay, sands, and sandstones. Several species of marine fossils can be found weathering out of Clayton outcrops, including mollusks, solitary corals, polychaetes, benthic foraminifera, fish teeth, and disarticulated fish bones. Notably, beds of the Clayton contain the index fossil for the early Danian in North America, the small oyster Pycnodonte pulaskensis (Smith, 1997). Faunal remains in these early Danian demonstrate distinct differences in faunal composition and diversity as a result of environment changes following the terminal Cretaceous extinction. Although exposures of the Clayton Formation and the K-Pg boundary are well documented in other locations, including Alabama and Texas, boundary exposures in Mississippi remain mostly unstudied, especially regarding early Danian macrofauna. This study utilizes outcroppings of the K-Pg boundary and Clayton Formation in three Mississippi counties (Oktibbeha, Noxubee, and Clay) for collection of fossils and stratigraphic data analysis. Results from Mississippi locales will be compared to more documented locations across the southeastern United States and mapped according to dominant fossils recovered. Analysis of benthic foraminifera conducted according to United States Geological Survey sampling guidelines will determine the age of beds to the lowest possible resolution. Results will be used to determine faunal turnover and changes in faunal diversity following the K-Pg extinction in northeast Mississippi.