Structural Analysis of the Great Smoky Thrust Sheet Along the Little Tennessee River

This study involves a structural analysis of a portion of the Great Smoky thrust sheet in the Great Smoky Mountains of Tennessee. Four groups of folds and related structures have been identified in this area. the earliest folds include second-order mesoscopic F1 folds with a slaty cleavage axial plane foliation (S1). These folds occur on the limbs of first-order macroscopic F1 folds which are discordant to the Great Smoky fault. In several places, the F1 folds are overprinted by mesoscopic F2 folds which are characterized by crenulation cleavage axial plane foliation (S2). F2 folds include tight to isoclinal folds with boudinage on fold limbs oriented subparallel to S2 and small, angular zigzag folds. Evidence indicates that some degree of transportation of foliations was involved in the formation of S2. Macroscopic F3 folds involve the folding of slaty cleavage (S1) and are probably related to the deformation of the Great Smoky fault surface, which resulted in its present undulatory nature. Mesoscopic F4 structures consist of kink bands and related thrust faults.

At least two major episodes of deformation can be recognized in the Taconic fold belt of the Blue Ridge province. The first episode involved the formation of "similar-type" folds with a slaty cleavage axial plane foliation, regional metamorphism, and thrusting on the Greenbrier fault. These structural features are believed to be representative of the Taconic orogeny (430-470 m.y. ago). A second period of deformation involved the formation of folds with a crenulation or slip cleavage axial plane foliation, emplacement of the Great Smoky and Blue Ridge thrust sheets and the creation of the Gatlinburg fault system. These events have been dated as Late Paleozoic (Mississippian or Pennsylvanian).

Structural elements in the area of this report can be differentiated into two major episodes of deformation. They can be integrated into the regional deformational history of the Blue Ridge in the following way. F1 folds correlated with the early period of deformation and regional metamorphism of Taconic age. F2 folds probably belong to the second period of deformation and are related to the Late Paleozoic thrust faulting. F3 and F4 postdate the Great Smoky fault.