STRUCTURE AND DETAILED GEOLOGIC MAP OF THE NORTHERN PORTION OF THE DUMPLIN VALLEY FAULT ZONE

The Dumplin Valley fault zone (DVFZ) is the easternmost fault in the Appalachian Valley and Ridge in Tennessee at the latitude of Knoxville. The DVFZ extends some 150 km from E of Morristown to SW of Madisonville, TN. It is characterized by two or more major faults, folding of both rock units and faults, and 10-15 km displacement. We have compiled the detailed geologic maps of the DVFZ from the northeastern end to just north of Maryville. Most of the rocks involved in the DVFZ at present erosion level belong to the Rome Formation (Lower Cambrian sandstone and shale) and Conasauga Group (Middle-Upper Cambrian limestones and shales; CG). Footwall units are dominated by Chickamauga Group (Middle Ordovician carbonate, shale, and sandstone) with some Knox Group (Upper Cambrian-Lower Ordovician dolostone and limestone) rocks.

Two major thrust faults trace throughout most of the northern DVFZ, with the southeastern French Mill fault (FMF) increasing displacement and overriding the northwestern Shields Ridge fault (SRF) in the SW third of the northern DVFZ. Both faults occur at the NE end, but two large FMF hanging-wall anticlines become imbricated to the SW. To the SW the SRF brings up Rome Formation, whereas the FMF involves only CG rocks. Farther SW, the FMF increases displacement, brings up Rome Formation, and overrides the SRF. N of Maryville, the FMF splays into several small S-trending faults and S-plunging anticlines that die to the S.

Both the SRF and FMF continue to the SW at least as far as Vonore, TN. The SRF maintains displacement, faulting CG rocks over Chickamauga and Knox Group rocks, but the FMF increases displacement to again bring up the Rome Formation near Vonore.

The DVFZ is one of several that detached from the Saltville fault, and may have formed out of sequence as the Saltville fault moved northwestward. The multi-fault DVFZ may have been localized here because of the almost equal proportions of shale and limestone in the CG.