Summary

New contour maps have been constructed of the upper and lower bounds of the deformed wedge of Paleozoic sedimentary rocks the southern Appalachian foreland fold-thrust belt from AL to VA. Industry, academic, and U.S./state geological survey seismic reflection and surface geologic data have been used, along with crustal seismic lines in the more internal parts of the orogen for these preliminary 2-D and 3-D reconstructions. The basement surface (lower bound) in our reconstruction dips gently SE in the TN embayment from VA to GA and contains several previously unrecognized rift-related large and small-displacement Neoproterozoic-earliest Cambrian normal faults. Several important previously unknown features related to the base of the Blue Ridge-Piedmont sheet (upper bound) have also been recognized as a result of this reconstruction. Frontal duplexes obliquely overridden along the leading edge of the BRP sheet at present erosion level are traceable for considerable distances beneath the sheet; and several internal isolated domes probably also formed by interactive footwall-duplex arching of the overlying thrust sheet. Boundary conditions include temperatures <200°C and pressures < 3 kb over most of the belt. Presence of low grade metamorphic rocks in a large reentrant exposed beneath the sheet in GA., but not in windows farther north or along the frontal edge in TN, may indicate the up-dip westward palinspastic limit of the BRP sheet is near its present-day trace and that the sheet was also relatively thin in TN, whereas in GA it may have extended as much as 30 km farther west and was much thicker than the frontal 30 km in TN.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah