Regional Tectonic Implications of Seismic Reflection, Gravity, Structural, and Stratigraphic Data from New Appalachian Ultradeep Core Hole (ADCOH) Site Study

R. D. Hatcher, R. T. Williams, J. K. Costain, R. A. Phinney, J. L. Hopson, A. L. Stieve, K. Roy-Chowdhury

The Appalachian Ultradeep Core Hole (ADCOH) site study area is located in the eastern Blue Ridge Mountains and western Piedmont of the Carolinas and northeastern Georgia. The goal of the proposed project is an ultradeep core hole that would penetrate and prove the existence of the main detachment thrust of the Blue Ridge-Piedmont (BRP) thrust sheet. Intermediate objectives include study of higher level faults and rock units within the thrust sheet, as well as investigation of the Paleozoic platform cover and basement beneath the BRP thrust sheet.

Site study data have revealed that the level of the main BRP detachment may have shallowed rapidly west of the Brevard fault zone, possibly bringing lower Paleozoic carbonate platform rocks to within 3-4 km of the surface near Hayesville, North Carolina, in a large duplex structure. If so, there are implications here and farther west for possible hydrocarbon accumulations. Duplex structure appears to be a dominant style of deformation both within and beneath the BRP thrust sheet. A recently discovered shear zone on the Tallulah Falls dome may represent an imbricate from one of the blind duplexes.

Newly discovered late Precambrian rift basins visible beneath the BRP detachment and the platform sedimentary rocks in both seismic reflection and gravity data may provide an additional deep target for scientific drilling. It is possible that the ADCOH may be drilled from a younger compressional environment into an older rifted margin environment.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.