High-resolution event stratigraphy (HiRES) of the Silurian across the Cincinnati Arch (USA) through integrating conodont and carbon isotope biochemostratigraphy, with gamma-ray and sequence stratigraphy

Abstract

ABSTRACT Silurian strata within the tristate area of Indiana, Ohio, and Kentucky have been thoroughly studied for well over a century. Due to rapid facies changes throughout the region numerous lithostratigraphic terminologies were established, many of which were difficult to correlate even over short distances. Recently these stratigraphic complexities have received renewed interest due to advancements in bio-, chemo-, and sequence stratigraphy that greatly improved our understanding of the tristate area. These improvements had significant implications for our ability to correlate Rhuddanian through lower Sheinwoodian strata between the Appalachian and Illinois basins and allowed unified nomenclatural and sequence stratigraphic hierarchies for this interval to be developed across the Cincinnati Arch. Recent advancements in regional chronostratigraphy of Silurian strata, however, highlight several discrepancies with regards to the 3rd- and 4th-order sequence stratigraphic hierarchies assigned within these basins. In an effort to alleviate these points of disagreement, we contribute new δ13Ccarb chemostratigraphic and sequence stratigraphic analyses of a basinward Appalachian section from Scioto County, Ohio, spanning upper Telychian through Gorstian strata assigned to the Estill through Tymochtee formations, complemented by gamma-ray core scans for localities traversing northwestward from the sampled core section into western Ohio. These new data allow unified nomenclatural and sequence stratigraphic hierarchies to be developed throughout the region for strata spanning the upper Telychian through Gorstian stages. Additionally, these findings highlight a significant shift in the primary sites of sediment accommodation during the studied depositional interval.