QUANTIFYING SHORTENING ACROSS THE CENTRAL APPALACHIAN FOLD-AND-THRUST BELT OF WEST VIRGINIA

The Central Appalachian mountains are a blind fold-thrust belt with very few to no thrust faults reaching the surface. For a belt of this nature, the total amount of shortening accommodated by folded rocks must equal the total amount of shortening accommodated by subsurface faults. Early attempts to balance the Central Appalachian salient assumed that the differnence in shortening between measured values at the surface and those estimated in the subsurfaces was due to grain scale layer parallel shortening (LPS). In order to reconstruct the geometry and potential kinematic evolution of the central Appalachian fold-and-thrust belt, we conducted new geologic mapping and associated sampling across a transect running from Elkins, West Virginia to Staunton, Virginia. 55 samples and over 300 joint orientations were collected from the Appalachian Plateau through the Valley and Ridge Province for grain-scale strain analyses and paleo-stress reconstruction, respectively. Collected joint orientations show two main joint populations trending at 321^o and 047^o, similar to published orientations from western Pennsylvania and New York. Strike of bedding ranged from 175^o to 012^o with a mean of 070^o. We integrate grain–scale bulk finitie strain data into a balanced cross section extending along this transect to document the total magnitude of shortening and compare that estimate to others across Pennsylvania to provide insight into the formation mechanism for the central Appalachian salient.