Abstract: Energy Resource Implications of 38th Parallel Lineament across Appalachian Basin

John M. Dennison, Garland R. Dever, Jr.

The 38th parallel lineament (fracture zone) across Kentucky, West Virginia, and Virginia, initially indicated by an alignment of igneous intrusions and structural features, is marked by distinct variations in sedimentary rock units, which are indicative of tectonic activity along the lineament. These factors have implications in the search for geothermal, oil, gas, coal, and uranium resources in the region.

Pulses of igneous activity have occurred along the trend of the fracture zone in late Precambrian, Devonian, Permian, Triassic, Jurassic, and Eocene times. Thermal-spring activity near the Eocene intrusions (western Virginia and eastern West Virginia) may be related to residual heat from a deep pluton still cooling, warranting exploration for geothermal resources.

Sedimentary rocks ranging in age from Cambrian to Pennsylvanian vary in distribution and thickness along the trend of the lineament. Early Paleozoic movement on the basement fault forming the northern boundary of the Rome trough in Kentucky resulted in depositional and erosional thinning of Cambrian and Lower Ordovician units northward across the fault. The Rome trough probably formed as a result of tectonic patterns accompanying the opening of the proto-Atlantic Ocean in late Precambrian time.

Mississippian tectonic activity is suggested by several patterns. In east-central West Virginia, the lineament is marked by an east-west belt where the Pocono Formation is absent, and by the northward disappearance of the Maccrady red beds and the Hillsdale (= St. Louis of Kentucky) and Denmar members of the Greenbrier Limestone. Uplift along an east-west axis in Mississippian time is proposed. Restriction of reported evaporites south of this axis suggests that it was positive during Maccrady deposition. The Gay-Fink and Cabin Creek channel deposits in the Berea Sandstone generally parallel the lineament and may represent westward drainage channeled along the sides of the uplift. Recurrent basement-fault movement in northeastern Kentucky is indicated by erosional removal of the St. Lo is and Ste. Genevieve members of the Newman Limestone and upper members of the Borden Formation in areas on the northern (upthrown) block.

Commercial coal in the Pottsville Group (Pennsylvanian) of West Virginia and Kentucky is concentrated in the area south of the lineament. In West Virginia, the New River and Kanawha Formations (Lower and Middle Pennsylvanian) are thick south of the lineament; on the north, they are thinner with a pronounced unconformity beneath the Pennsylvanian. The lower tongue of the Breathitt Formation (Lower Pennsylvanian) thins northward across the basement fault in northeastern Kentucky.

Uranium possibilities in the Hampshire Formation (Upper Devonian) may be enhanced by the unconformity at the top of the formation in the West Virginia area of no Pocono, where Mississippian geochemical cells could have concentrated uranium in the Hampshire. Uranium geochemical cell concentrations in the Pocono could occur along the flanks of the Mississippian uplift.

AAPG Search and Discovery Article #90975©1976 GCAGS- GC Section SEPM Annual Meeting Shreveport, Louisiana