A LITHOSTRATIGRAPHIC, BIOSTRATIGRAPHIC, AND PETROGRAPHIC ANALYSIS OF MIDDLE AND UPPER ORDOVICIAN STRATA IN THE SOUTHERN CHAMPLAIN VALLEY, NEW YORK: PRELIMINARY CORRELATION OF STRATIGRAPHY AND NOMENCLATURE IN THE CENTRAL AND NORTHERN APPALACHIANS

The Middle and Upper Ordovician stratigraphic framework throughout the Appalachians is complex and has created confusion in nomenclature for over a century. A better understanding of the depositional environments and facies changes in this mostly carbonate rock sequence will result in a more precisely defined local and regional lithostratigraphic framework. To achieve this goal, we focused on previously measured sections, newly measured sections provided by the authors, conodont biostratigraphy, microfacies analysis, and detailed 1:24,000 scale geologic mapping from West Virginia, Virginia, New York, and Vermont. Previous workers have made detailed measurements of representative sections throughout this region, and those measurements and descriptions are compared with our work in these states. Samples of various dolostones and limestones are used to provide detailed petrographic characterization of framework grains, matrix, cement, porosity, characterization of microfacies, and these data have been used to target rocks for further processing for conodonts. The recovery of conodont elements has resulted in regional conodont biostratigraphic correlations, thus aiding in the correlation of various microfacies and formational contacts throughout the region both along and across strike. A comparison of measured sections shows that issues of nomenclature which predate the North American Stratigraphic Code have persisted into the present time. Our work in Middle and Upper Ordovician Appalachian stratigraphy includes a multi-faceted analysis of stratigraphic sections of Middle and Upper Ordovician carbonates, and it provides a model for future use that can be applied to efforts involving the reconciliation of stratigraphic and nomenclature issues throughout this and other areas of the central and northern Appalachians.