Abstract

Subhorizontal shear sense along subvertical mylonite zones marking the southeast and northwest flanks of the Pine Mountain belt in Alabama, i.e., the Towaliga, Bartletts Ferry, and Goat Rock fault zones, has been deduced from S-C composite planar fabrics, extensional shear bands, displaced broken grains, asymmetric folds, and porphyroclast systems. Quartz and feldspar elongation lineations are generally subhorizontal and closely correspond to estimated sliplines. Each of the fault zones records dominantly dextral shear; the Towaliga has an apparent minor oblique, down-to-the-north normal component, and the Goat Rock has a minor down-to-the-south normal component. The mylonite zones postdate the early to middle Paleozoic schistosity in rocks outside the shear zones and thus are considered to be late Paleozoic in age. Results imply persistence of the late Paleozoic (Alleghanian?) dextral shear system into the southernmost exposures of the Appalachian orogen.

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