NEW DIGITAL GEOLOGIC MAP OF THE WESTERN BLUE RIDGE, SE TENNESSEE, SW NORTH CAROLINA, NORTHERN GEORGIA: A TOOL FOR REGIONAL ANALYSIS OF THE OCOEE BASIN

The southern Appalachian western Blue Ridge (WBR) in SE Tennessee, SW North Carolina, and northern Georgia is bound to the NW by the Great Smoky and Miller Cove-Cartersville faults, and to the SE by the Allatoona-Hayesville fault. It preserves Neoproterozoic-Ordovician (?) synrift, rift-to-drift, and platform rocks deposited along the SE Laurentian margin following the ~565 Ma breakup of Rodinia and Middle Ordovician clastic wedge (?) rocks (Murphy belt) deposited during the Taconic (Ordovician) orogeny. This sequence was originally deformed and metamorphosed ~455 Ma during the Taconic, and then transported westward during the Alleghanian (Permian) orogeny. The Ocoee Supergroup (OSG), the major WBR sequence, consists of Late Proterozoic-Early Cambrian rift-related siliciclastics and minor carbonates, estimated to have a maximum thickness of 15 km in Great Smoky Mountains National Park (GSMNP). The basal unit of the OSG (Snowbird Group) rests nonconformably on Grenville basement. The middle unit (Great Smoky Group) is overlain in the central WBR by Murphy belt rocks, and to the west by the upper OSG units (Walden Creek Group), Lower Cambrian Chilhowee Group and Shady Dolomite. Compilation and reanalysis of earlier geologic interpretations in the WBR, and recent detailed mapping in an area of regional structural/stratigraphic incompatibility provides new insight for correlation of OSG units. Recognition of facies and thickness changes, and termination of OSG units both along strike and across major Paleozoic thrust sheets permits realistic interpretation of primary relationships. The Shields Formation (Miller Cove sheet), while less feldspathic than the Dean Formation (Rabbit Creek and Greenbrier sheets), lies in the same stratigraphic position beneath the Wilhite Formation, possibly suggesting that the Shields is a more distal facies of the Dean. Based on map relationships SW of GSMNP, the Dean Formation is correlated with the Cades Sandstone (stratigraphic position previously unknown due to faulted contacts). The Copperhill Formation is correlated with the Elkmont and Thunderhead Sandstones in GSMNP based on lithologic similarities and stratigraphic position. The Wehutty Formation, overlying the Copperhill, is correlated with the Anakeesta Formation, which overlies the Elkmont/Thunderhead sequence in GSMNP.