INTER-BASINAL DEVONIAN LINKAGES: A CORE-BASED GEOCHEMICAL AND ISOTOPIC TRANSECT ACROSS THE CUMBERLAND SADDLE OF THE CINCINNATI ARCH, SOUTH-CENTRAL KY

A potentially unique aspect of the evolution of the Appalachian and Illinois basins is explored through the examination of relatively thin (<15 meters), Devonian/Mississippian black shale intervals preserved along a structurally lower segment of the roughly N/S-trending Cincinnati Arch, known as the Cumberland Saddle. The saddle, situated along the crest of the Cincinnati Arch between the structurally higher Jessamine and Nashville domes, presumably acted as a barrier that, at times, hydrographically separated two major depositional basins in eastern North America (Illinois and Appalachian basins). The purpose of the present study is to further define the influence of the saddle on inter-basinal sedimentation and hydrography and to further assess the degrees to which the two basins were coupled or decoupled. A suite of five cores that transect the saddle (~120-km transect) were chosen in order to characterize temporal and spatial variability in depositional environment across the inundated basin margins. Stratigraphic, sedimentological, and geochemical signatures were used to characterize the spatial variability in depositional environment on the crest and flanks of the saddle. Preliminary geochemical analysis of the core centered on the crest of the saddle corroborates previously-assigned stratigraphic (gamma) divisions within the New Albany Shale, including the Clegg Creek, Camp Run, and Blocher/Duffin members. The high degree of organic preservation in the core (max = 24%C; avg. = 11%C) suggests that either high productivity and/or anoxic conditions prevailed in both basins during much of the deposition. The geochemical signatures from the saddle, when compared to contemporaneous deposits preserved basinward, potentially define the unique set of conditions that existed during inter-basin communication. A full assessment of redox-sensitive trace elements, %C and %N, C and N isotopes, and Rock Eval for each core will be presented.