Expression of Cenomanian-Turonian OAE2 on the East Coast of North America

Decades of warming oceans and increased terrigenous nutrient flux are causing a decline in dissolved oxygen in the world's marine ecosystems, particularly in coastal waters. To better understand the oceanographic processes that promote the development of anoxia on shelf environments, and how that anoxia effects the biota, it is necessary to look to the past. One of the best examples of widespread oceanic anoxia driven by eutrophication is the mid-Cretaceous Oceanic Anoxic Event 2, which spans the Cenomanian-Turonian boundary. Although recent work has shown that the highest rates of organic matter burial during this event occurred on shelf environments, much of these data come from continental margins prone to upwelling. Shelf environments along the northwestern Gulf of Mexico were not prone to upwelling in the Late Cretaceous, and record maximum carbon burial either before or after OAE2, driven primarily by local changes in sea level. It is unclear if these trends are limited to the Gulf Coastal Plain or if they characterize other shelf environments not predisposed to upwelling. Here, we present the first carbon isotope and organic carbon data from the Clubhouse Formation of the North Carolina Coastal Plain recovered from the Hope Plantation (BE-110) and Smith Elementary School (CR-675) cores drilled by the U.S. Geological Survey in the 2000s. The Clubhouse Formation consists of glauconite-rich clayey, silty sand deposited in a neritic environment and most likely represents one transgressive-regressive cycle with parasequences representing higher-order sea level changes. Preliminary work places the lower part of the study interval in the late Cenomanian calcareous nannofossil Zone CC10a, based on the presence of Lithraphidites acutus, Cretarhabdus loriei, and Axopodorhabdus albianus, combined with the absence of Corollithion kennedyi. The age of the upper part of the study interval is questionably placed in early Turonian Zone CC10b. Planktic and benthic foraminifera counts are used to tie observations of organic matter burial to sea level changes throughout the Clubhouse Formation. OAE2 is essentially unstudied on the US Coastal Plain between New Jersey and Mississippi, and this new work fills an important gap in our understanding of how the western Atlantic margin responded to this important event.