GEOLOGIC MAPPING OF THE NEWPORT QUADRANGLE, TENNESSEE: MAKING A CASE FOR THE SOUTHWEST CONTINUATION OF THE PULASKI FAULT

Detailed geologic mapping of the Newport 7½' quadrangle located in the Tennessee portion of the southern Appalachian foreland fold-thrust belt was completed in 2005. The field work and open file GIS-based geologic map product was partially funded by the USGS STATEMAP program. The area was chosen by the Tennessee Mapping Advisory Committee because it contains a major transportation corridor (I-40), and numerous hazardous waste and superfund sites. One unexpected outcome of this work is data to support the southwest continuation of the Pulaski fault (or its equivalent) into the map area.

Previous work in the Newport area consisted of reconnaissance mapping to determine the extent of the Cambro-Ordovician Knox Group and Middle Ordovician Sevier Shale, and more detailed thesis mapping of the Lower Cambrian Chilhowee Group on English Mountain and Stone Mountain. The Tennessee State Geologic Map depicts the Pulaski fault either merging with the Neddy Mountain fault or being overridden by the Neddy Mountain thrust sheet in the adjacent quadrangle.

Where previously mapped the Pulaski fault in Tennessee is a distinctive boundary. Some of the geologic attributes that are characteristic of rocks contained within the Pulaski thrust sheet are: (1) the Upper Cambrian Maynardville Limestone is capped by a sandstone; (2) the Knox Group facies consists of the Upper Cambrian Conococheague Limestone and Lower Ordovician Jonesboro Limestone; (3) numerous tight upright and overturned map-scale folds; and (4) hinge zone cleavage development in the folded carbonates of the Knox Group. All of the preceding attributes occur in the hanging wall of a northeast-southwest striking fault mapped in the Newport area. Northwest of this fault, the footwall consists of: (1) the Newala Formation facies of the Knox Group; (2) one broad open fold and other map-scale folds in the Knox Group that are not overturned; and (3) except for a few instances, the folds in the Knox Group carbonates are devoid of cleavage. All of these attributes also typically occur to the northwest of the Pulaski fault. Therefore the fault mapped in the Newport area may be the southwest continuation of the Pulaski fault, but detailed mapping of the adjacent Neddy Mountain quadrangle is needed to confirm this hypothesis.