A Regional Geologic Cross Section Through the Appalachian Basin from near the Findlay Arch, Erie County, North-Central Ohio, to the Valley and Ridge Province, Bedford County, South-Central Pennsylvania

Robert T. Ryder, Michael H. Trippi, Christopher S. Swezey, Robert D. Crangle, Jr., Rebecca S. Hope, Elisabeth L. Rowan, and Erika E. Lentz
U.S. Geological Survey, Reston, VA 20192

A new geologic cross section through the Appalachian basin provides a regional perspective for evaluating petroleum systems, thermal maturity patterns, and burial history models. The cross section is constructed from eleven wells, three of which bottom in Grenville-age crystalline basement rocks. Sedimentary rocks along the cross section span most of the Paleozoic Era and their approximate preserved thicknesses range from 3,000 ft near the Findlay arch to 32,000 ft near the Rome trough and Laurel Hill anticline in Fayette County, southwestern Pennsylvania. These rocks are broadly classified as follows: 1) Lower Cambrian to Upper Ordovician rift and passive margin siliciclastic and carbonate deposits; 2) Upper Ordovician to Lower Silurian Taconic orogeny foreland basin siliciclastic deposits; 3) Lower Silurian to Middle Devonian shallow marine carbonate and evaporite deposits; 4) Middle Devonian to Lower Mississippian Acadian orogeny foreland basin siliciclastic deposits; 5) Upper Mississippian shallow marine carbonate deposits; and 6) Upper Mississippian, Pennsylvanian, and Lower Permian Alleghanian orogeny foreland basin siliciclastic deposits. Regional unconformities, such as the Knox unconformity, are caused by falls in eustatic sea level and (or) tectonic uplift. Styles of deformation illustrated are: 1) thin-skinned contractional structures of Alleghanian origin in the Valley and Ridge province (Wills Mountain and Evitts Mountain anticlines) and in the adjoining Allegheny Plateau province (for example, Laurel Hill and Chestnut Ridge anticlines) and 2) basement-involved Middle Cambrian extensional faults of the Rome trough. Several deeply rooted anticlines show aspects of both thin-skinned and basement-involved styles of deformation.

Presented AAPG Eastern Section Meeting, Pittsburgh, Pennsylvania 2008 © AAPG Eastern Section