Sedimentation and Techtonics Within the Upper Precambrian Wilhite Formation of the Great Smoky Mountains, Eastern Tennessee

Naylor, Clifton

The Upper Precambrian Wilhite Formation lies within the upper portion of an 8- to 12-km thick sedimentary sequience, the Ocoee Supergroup, which is thought to have accumulated in one or more basins formed in association with the initial opening of the Iapetus Ocean. Seven major lithofacies are recognized from exposures of the Wilhite Formation along the Little Tennessee River west of the Great Smoky Mountains. All resulted from the resedimentation of carbonate and siliciclastic detritus as gravity flows within the inner-fan channel, interchannel, and slope environments of submarine fans. Although there is no preserved record of in situ shallow-water sediments in the area, petrographic and outcrop study of resdimented material indicates that the shallow-water environment was characterized by contemporaneous deposition of both carbonates and siliciclastics under very high-energy conditions. The coarse grain size and well-rounded nature of basement-derived siliciclastics suggests that they were derived from source areas of significant relief. The implied relief of these source areas, together with large sedimentary rock fragments of recycled Ocoee origin, indicates that deposition occured adjacent to a tectonically active basin margin. Similar high-energy, mixed carbonate/siliciclastic shelves are common within modern extensional basins exhibiting significant marginal uplift. Sedimentation upon such shelves is commonly characterized by fan deltas. Wilhite deposition is herin postulated to have occurred near the base of a submarine slope, below just such a fan delta-dominated shelf.