STRUCTURAL AND STRATIGRAPHIC RELATIONSHIPS NEAR THE SOUTHERN TERMINUS OF THE PULASKI FAULT, ONE OF THE DOMINANT STRUCTURES IN THE APPALACHIAN FORELAND FOLD-THRUST BELT

The Pulaski is one of the master Alleghanian thrust faults in the Valley and Ridge fold-thrust belt of Tennessee and Virginia, along with the Saltville and Whiteoak Mountain faults. Detailed field mapping of Late Cambrian through Middle Ordovician strata in northeastern Tennessee provides a basis for determining emplacement kinematics near the southwestern terminus of the Pulaski fault. Mapping revealed key structural and stratigraphic characteristics for distinguishing the Pulaski thrust sheet from its footwall, the Saltville thrust sheet. Several tight, pre-faulting macroscale folds typify the folding style of the Pulaski fault hanging wall. Many of the folds are disharmonic, which is probably related to the presence of a mechanically weak Upper Cambrian shale unit sandwiched between the more competent carbonate units. In contrast, broad and mostly open folds occur northwest of the Pulaski fault trace, typical of folding in the thick Cambro-Ordovician carbonate sequence within the Saltville thrust sheet. Unlike most thrust systems in the Valley and Ridge, the Pulaski sheet may exhibit two folding phases. The irregular trace of the Pulaski fault in this area favors additional post-emplacement folding. Significant changes in stratigraphy are also present on opposite sides of the fault. Upper Conasauga and Knox Groups within the Pulaski thrust sheet consist of less dolomite and fewer stratigraphic markers useful for subdividing the Knox Group northwest of the fault, but some markers occur in the Pulaski sheet. Lower Conasauga Group rocks within the thrust sheet contain more dolomite and thin traceable to untraceable shale units. These dissimilarities between thrust sheets document key telescoped facies changes that can be used to locate the Pulaski fault trace and reconfirm its fundamental character. Our data suggest that the Pulaski fault was overridden by the thin-skinned Great Smoky fault, which marks the westernmost boundary of the Blue Ridge province. The kinematic and geometric interrelationships between the Pulaski and other Valley and Ridge faults provide useful insight into the processes of footwall/hanging wall deformation and thrust propagation in thin-skinned foreland fold-thrust belts.