Thin-skinned tectonics in the crystalline southern Appalachians; COCORP seismic-reflection profiling of the Blue Ridge and Piedmont
COCORP seismic-reflection profiling in Georgia, North Carolina, and Tennessee and related geological data indicate that the crystalline Precambrian and Paleozoic rocks of the Blue Ridge, Inner Piedmont, Charlotte belt, and Carolina slate belt constitute an allochthonous sheet, generally 6 to 15 km thick, which overlies relatively flat-lying autochthonous lower Paleozoic sedimentary rocks, 1 to 5 km thick, of the proto-Atlantic continental margin. Thus, the crystalline rocks of the southern Appalachians appear to have been thrust at least 260 km to the west, and they overlie sedimentary rocks that cover an extensive area of the central and southern Appalachians. The hydrocarbon potential of these sedimentary rocks is unknown and untested. The data show that the Brevard fault is the surface expression of an eastward-dipping splay off the main sole thrust, and they show, or imply, that other major faults of this region have similar origins. The data support the view that large-scale, thin crystalline thrust sheets may be significant features of orogenic zones.