Conodont-Based Reinterpretation of Bane Dome--Structural Reevaluation of Allegheny Frontal Zone: GEOLOGIC NOTES

Abstract

The F. P. Strader 1 well drilled on the crest of the Bane dome, in Giles County, Virginia, has been cited as direct evidence for basement uplift under the dome. This concept was based on the assumption that the well contained a normal stratigraphic sequence of Lower Cambrian rocks from Rome Formation at the surface to Shady Dolomite in the subsurface. Conodonts, recently recovered from cuttings of the Strader well show that the dolomites, thought to be Lower Cambrian, are actually Lower Ordovician and are part of the Knox Group. Therefore, the base of the Rome at 28 ft (8.5 m) in the Strader well is marked by a major thrust fault. We have interpreted this thrust as part of the Saint Clair fault system and attribute the formation of the Bane dome to imbrication at the trai ing edge of the Saint Clair footwall. The subsurface data refute active-basement tectonics and support thin-skinned tectonics in this area. Our reinterpretation adds more than 10,000 ft (3,300 m) of gas-prospective section and several attractive structural traps that remain to be drilled.