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The Jacks Mountain anticlinorium is a high, continuous structure in the Pennsylvania Valley and Ridge Province midway between the Blue Mountain and Allegheny structural fronts. Evolution of its northwest limb proceeded through a number of structural stages that may be characteristic of the first-order anticlines of the middle Appalachians.

Prior to major folding, faults rising to the northwest off the proposed Antes-Coburn detachment developed in sequence as the Stone Mountain duplex, the Bearpen Hollow thrust and the Potlicker Flat thrust, all cutting Silurian rocks. These were later passively folded to northwest dips during growth of the anticlinorium above the contracting and imbricating Cambro-Ordovician duplex. The northwest limb near the Stone Mountain duplex underwent later-stage layer-parallel extension and steep out-of-sequence reverse or strike-slip faulting, which were caused by the larger amounts of limb rotation and fold flattening at this part of the anticlinorium. Faults associated with this later event have mineralized pressure-solved breccias, suggesting that different deformation conditions prevailed.

Evaluation of the poorly exposed Antes-Cobura detachment has not provided structural evidence of a systematic transport direction, but allows interpretation of this zone as both an early floor thrust for imbricates rising to the northwest into overlying Silurian rocks and a later boundary zone between parts of the stratigraphic section undergoing unequal layer-parallel shortening.

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