PROVIDING HIRES CHRONOSTRATIGRAPHIC CONSTRAINT TO THE UPPER SILURIAN SALINA GROUP WITHIN THE APPALACHIAN, AND MICHIGAN BASINS

Silurian strata assigned to the Salina Group within the Appalachian and Michigan basins have been thoroughly studied for well over a century. These former investigations provided a general understanding of unit distributions throughout the region and permitted the development of paleo-models for facies distribution, water-mass mixing, evaporite deposition, and sequence stratigraphy. Many of these regional and historic chronostratigraphic correlations hold strong still to this day; however, advancement within HiRES methodologies in the last few decades have highlighted several discrepancies throughout the region with some historic correlations off by as much as a full Series. These miscorrelations therein affect previous paleoenvironmental models and hamper reliable establishment and regional correlation of chronostratigraphic horizons and the extension of these chronostratigraphically constrained horizons to global Series and Stage boundaries.

Here, we provide new δ¹³C_carb chemostratigraphic data from central Ohio along the western margin of the Appalachian Basin where the Salina Group reaches its maximum regional thickness. These data are coupled with subsurface regional geophysical analyses that permit their extension to sites with previous biochemostratigraphic data located in western, and southern Ohio, and to subsurface salt nomenclature of the Salina Group in eastern Ohio. Our synthesis of these regional biochemostratigraphic data provides a chronostratigraphic constraint for strata of the Salina Group of the Appalachian, and Michigan basins and demonstrates that the Salina Group spans an interval encompassing the upper Wenlock through basal Pridoli. Furthermore, we demonstrate that the type sections for the Tymochtee and Greenfield formations are based on laterally equivalent lithostratigraphic units and that the historical use of Tymochtee to imply a majority of Salina Group strata should first be restricted to a chronostratigraphic position within the upper Wenlock and secondarily be abandoned in favor of the senior Greenfield nomenclature.