Abstract: The Appalachian Blue Ridge - A Frontier Province

By

Leonard D. Harris

Seismic-reflection studies in the southern Appalachians have established that the basic geologic framework of the Appalachian orogen consists of a low-angle megathrust-fault system, stretching from the Appalachian Plateaus to the Continental Shelf. In this system, igneous and metamorphic rocks of the Blue Ridge end Piedmont have been thrust westward, burying a large segment of the sedimentary rocks of the Valley and Ridge. Thus, the Blue Ridge, and perhaps a small part of the Piedmont, forms an unusual frontier province, in which the entire surface is composed of rocks commonly referred to as "basement" by petroleum geologists and the subsurface composed of sedimentary rock having unknown hydrocarbon potential. Our current studies indicate that within the Appalachian orogen, regional thermal patterns, which have a direct bearing on the maturity levels of organic matter in sedimentary rocks, existed prior to thrusting. Westward movement of thrust sheets disrupted and telescoped that pattern by placing thermally more mature eastern rocks over less mature western rocks. Palinspastic reconstruction of the original thermal pattern emphasizes that more than 10,000 feet of Lower Paleozoic rocks with possible commercial gas potential, extend eastward for about 60 miles in the subsurface beneath the Blue Ridge in the southern Appalachians.

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