Geologic Cross Section through the Appalachian Basin from Sandusky County, Ohio, to Hardy County, West Virginia
U.S. Geological Survey, Reston, VA
A new geologic cross section through the central Appalachian basin provides a regional structural and stratigraphic context to better understand petroleum systems, coal systems, and basinwide fluid-flow models. The cross section is constrained by 13 drill holes, 4 of which penetrate the Paleozoic cover rocks of the basin and bottom in Grenville-age crystalline basement rocks, and by regional structure contour maps. Sedimentary rocks shown on the cross section span most of the Paleozoic Era, and their preserved thicknesses range from about 3,000 ft on the Findlay arch to about 27,000 ft in the Rome Trough near the Chestnut Ridge anticline extension. These rocks are broadly classified as follows: (1) Lower Cambrian to Upper Ordovician siliciclastic and carbonate strata (rift and passive margin deposits); (2) Upper Ordovician to Lower Silurian siliciclastic strata (Taconic orogeny foreland basin deposits); (3) Lower Silurian to Middle Devonian carbonate and evaporite strata (shallow marine deposits); (4) Middle Devonian to Lower Mississippian siliciclastic strata (Acadian orogeny foreland basin deposits); (5) Upper Mississippian carbonate strata (shallow marine deposits); and (6) Upper Mississippian, Pennsylvanian, and Permian siliciclastic strata (Alleghanian orogeny foreland basin deposits). Styles of deformation illustrated are: (1) thin-skinned contractional structures of Alleghanian origin at the Allegheny structural front (Wills Mountain anticline) and in the adjoining foreland (Blackwater, Deer Park/Leadmine, and Etam anticlines) and (2) basement-involved Middle Cambrian extensional faults that flank the Rome trough. At several localities, deeply rooted anticlines that involve basement rocks appear to have been caused by fault-block reactivation during the Alleghanian orogeny.