16 Ordovician Tectonics of the Appalachians: New Ideas on an Ancient Orogen

Thursday, 19 March 2015
1:00 PM - 5:00 PM
Roberts

IMPLICATIONS OF THE VARIATIONS IN LITHOLOGY OF THE WILHITE FORMATION EXPOSED ALONG ROADS BY THREE RIVERS IN THE SOUTHEASTERN TENNESSEE BLUE RIDGE

Paper number: 16-5
Program: Theme Sessions
Time: 2:05 PM – 2:25 PM

Authors

  • Habte G. Churnet Presenting Author
    University of Tennessee at Chattanooga, Chattanooga, TN

Abstract

The little Tennessee, the Hiwassee, and the Ocoee rivers cut across the metamorphosed and deformed Ocoee Supergroup (OS) in the Southeastern Tennessee Blue Ridge. The rocks were likely metamorphosed during the Taconic orogeny. Hatcher (2012) shows the geology of southeastern Tennessee including the Wilhite Formation. The Wilhite is dominated by fine-grained turbidite northeast of Abrams Creek, and by carbonate rock outcrops along the Foothills Parkway near its junction with HWY 129 and southward. The Wilhite is composed of conglomeratic beds at the Chilhowee Dam. The Laurentian passive margin consisting of marginal marine siliciclastics dominated by the Great American Carbonate Bank could not have been a provenance for the conglomeratic Wilhite Formation at the Chilhowee Dam. The inference is that the provenance was gneissose, and the blue quart in it points to Precambrian rocks. In contrast, the Wilhite near the confluence of the Hiwassee River and Wolf Creek is cross-bedded (Petsch and Churnet, 2014) and likely formed in a shallow marine environment. At the Ocoee Gorge, the Wilhite conformably overlies the Dean Formation, or according to Tull et al. (2012) the Nantahala Formation overlies the Dean, which further up the stratigraphy, is unconformably overlain by the Wilhite.

The OS was likely transported from its depositional site some 400 km away from the southeast (Hatcher et al., 2007), and knowledge of the exact spatial depositional setting within the OS is subject to interpretation. The presence of conglomerates proximal to fine grained deposits and unconformable zones may likely be explained by formation in settings of half grabens with border faults and transfer zones, and the conglomerate developed at a border faults of the grabens. Nested half grabens described for East African Rift (Rosendahl, 1987) might explain features describe about the OS.