Burial and Thermal History Models of the Central Appalachian Basin, Ohio, Pennsylvania, and West Virginia

Rowan, E.L., Ryder, R.T., Repetski, J. E., Trippi, M. H. and Ruppert, L. F.

U.S. Geological Survey, 12201 Sunrise Valley Dr., MS 956, Reston, VA 20192

Three models of burial and thermal history have been developed for the undeformed north-central Appalachian basin based on regional-scale, 2D cross-sections.  The models integrate thermal and geologic data to provide the most accurate possible burial, uplift, and erosion history.  The cross-sections extend from the Allegheny structural front in West Virginia and Pennsylvania northwestward across the Rome trough and terminate on the Findlay Arch in northwestern Ohio. 

The models incorporate sedimentation, compaction, uplift, and erosion, and assume a constant basement heat flow of 52 mW/m².  Relatively low thermal conductivities are assigned to Pennsylvanian coal beds (0.2 W/mºC) and to Devonian kerogen-rich shales (0.9–1.2 W/mºC), based on published values from the region. The models are constrained by corrected bottom hole temperatures and by measurements of conodont color alteration index (CAI) and vitrinite reflectance (R_o%) from Ordovician, Devonian, and Pennsylvanian rocks. To match the measured thermal maturities, the models require deposition of additional Permian-Triassic sediment, subsequently removed by erosion. We assumed that maximum burial occurred during the Triassic with deposition of a wedge of sediment, ~7700 ft thick at the southeast end of the section and thinning northwestward. The burial/thermal history models permit the thermal maturities of individual hydrocarbon source rocks to be calculated across the region.  The models also provide the regional-scale temperature and pressure framework needed to model hydrocarbon migration.