Hydrocarbon Potential of Middlesboro Crater, Bell County, Kentucky

W. S. Hale-Erlich, J. L. Coleman, Jr., C. D. Faris

The Middlesboro crater is a 3.6 mi (5.8 km) diameter circular feature located within the Appalachian thrust belt, near the common junction of Kentucky, Tennessee, and Virginia. K. J. Englund first suggested that the feature was the result of a meteor impact. This study reinforces that position and suggests that it may have significant potential as a hydrocarbon producer. Productive analogous features are known from the Williston basin and south Texas.

Crater formation is believed to be post-Alleghenian thrusting (latest Pennsylvanian?), because the feature is not disturbed by Alleghenian transport of the Pine Mountain block, which it overlies. A postulated structural configuration was developed from outcrop data and empirical relationships between outer rim and central peak dimensions for complex type craters. Although the feature is developed in a normal stratigraphic section of Cambrian to Pennsylvanian units, the potential reservoir probably will be a commingled pile of rubble, composed of Mississippian to Lower Ordovician blocks. This brecciated mass represents the central uplift of the feature and the zone of most intensive deformation. Source rocks are regionally present in the Devonian Chattanooga Shale and, secondarily, in solated Mississippian and Pennsylvanian shales. A surface geochemical survey, conducted over the central part of the feature, indicates oil-prone hydrocarbons are present in the subsurface. Anomalously high geochemical values delineate a subcircular zone of hydrocarbon microseepage corresponding to a ring of massive fracturing bordering the central uplift.

Hydrocarbon reserves at the Middlesboro structure are estimated at 16 million bbl of oil, based on both theoretical and empirically derived relationships between central uplift and total crater dimensions.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.