Paper No. 13
Presentation Time: 11:30 AM
NEW INSIGHT INTO THE K/PG BOUNDARY RECOVERY COMMUNITY IN THE ATLANTIC AND GULF COASTAL PLAIN FROM SITES IN NEW JERSEY, MISSISSIPPI AND ALABAMA
Throughout the Atlantic Coastal Plain and Gulf Coastal Plain, the Cretaceous / Paleogene (K/Pg) boundary (~ 66 Ma) outcrops in a thin belt. Recently, new marine exposures of the K/Pg boundary have been discovered, providing new insights on how organisms were affected by the Chixculub impact, and how they recovered as the environment stabilized. One of these new sites is Lower Agony Creek, located in Monmouth County, NJ. The site contains the Burrowed Unit which Landman et. al.(2012) interpreted as being the last remnants of the dying Cretaceous community. Directly above this unit is the Hornerstown Formation, which contains a faunal community representative of the lowest Danian. A general description of the K/Pg recovery community in New Jersey by Gallagher (2002) suggests they were composed mainly of brachiopods with a few sponges and corals 2 m above the boundary. The area in between the brachiopod bed and the boundary were found to be mostly barren. However, at Lower Agony Creek, a community dominated by the small bivalve Ostrea pulaskensis was discovered directly above the boundary, suggesting a more rapid recovery than previously observed. O. pulaskensis and a similar oyster, Gryphaeostrea vomer have also been found in abundance at sites in Mississippi and Alabama at the base of the lower-most Danian Clayton formation. At The Prarie Bluff landfill near Houston, Mississippi, a clastic unit is observed directly above the K/Pg boundary with spherules at the base that is believed to be related to post-impact tsumais and shelf collapse. Above the clastic unit is a silty unit appears with very few fossils, followed by a chalkier unit where G. vomer is abundant, along with small gastropods. Similarly, a site near Starkville MS has a non-conformable K/Pg boundary above which is a silty unit that contains very few fossils, followed by a chalkier unit that contains abundant O pulaskensis, as well as small gastropods. “Mooseland”, a new site near Prairie Bluff AL, contains the boundary with similar post-impact deposits: a clastic unit containing spherules followed by a chalkier unit that contains O. pulakensis and small gastropods in abundance. These new sites provide a more detailed account of how marine fauna responded and recovered from the environmental changes assiated withthe K/Pg event.