Abstract

The Pulaski fault system is a complex series of Alleghanian thrusts which has juxtaposed rocks of the Pulaski thrust sheet over rocks as young as Early to middle Mississippian (Maccrady Formation) of the Saltville thrust sheet. The Salem branch, a later major branch of the Pulaski fault system within the Pulaski thrust sheet, displaced the complexly deformed plate containing a broken formation (a lithotectonic assemblage of complexly folded and faulted Elbrook and Rome carbonates and shales with associated breccias) over rocks as young as Early Mississippian (lower Price Formation) of the Salem synclinorium. The classic, ubiquitous Max Meadows breccias generally are confined to the broken formation, which forms the basal part of the complexly deformed plate and which is interpreted as an exhumed lower level décollement zone formed during an earlier Alleghanian stage and transported during a later Alleghanian stage of deformation to a much higher structural level.

Minimum displacement of the complexly deformed plate is on the order of 100–110 km, on the basis of a new palinspastic reconstruction of the Pulaski thrust sheet. On the basis of this reconstruction and of two balanced and restored cross sections for the western portion of the Valley and Ridge, minimum shortening for the Pulaski thrust sheet is ∼80%, whereas that for the western part of the Valley and Ridge province is only ∼10%–20%. The Pulaski fault system is interpreted to have originated below the Appalachian-wide basal décollement zone near the contact between the Cambrian Rome and Elbrook Formations.

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