REEVALUATING STRATIGRAPHIC ASSIGNMENTS OF APPALACHIAN WESTERN BLUE RIDGE STRATIGRAPHY, GEORGIA AND TENNESSEE

The frontal metamorphic (Blue Ridge) allochthon in the S. Appalachians contains the Ocoee Sg. (OSG), recording the rifting of supercontinent Rodinia, followed by transition into Laurentia’s SE Atlantic-type margin. The OSG is conventionally subdivided into: Snowbird, Great Smoky (GSG), and Walden Creek (WCG) Groups, but tectonic separation of the latter two resulted in their stratigraphic relationships being indeterminate.

Along its NW flank the WCG is disconformably overlain by the Lower Cambrian Chilhowee Gp. (CG). However, adding to the uncertainty of the distribution of the WCG are recent paleontological discoveries indicating a fault-bounded part of the sequence (SE of the CG panel and structurally beneath [NW of] the Epperson synclinorium [ES]) formerly designated as WCG is as young as Siluro-Devonian. To the SE, within the Murphy synclinorium (MS), the GSG is overlain conformably by the Nantahala & Brasstown Fms. (NBF), outboard CG equivalents, marking the rift-to-drift transition. The NBF is stratigraphically overlain by the Murphy Marble, which is in turn unconformably overlain in the core of the MS by the post-Cambrian Mineral Bluff Gp. An observation not fully realized in regional correlations is that the NBF reappears to the W of the MS on the NW overturned flank of the Ducktown anticline (SE flank of the ES), and is stratigraphically overlain by rocks also assigned in conventional interpretations to the WCG. The current study seeks to determine if this controversial stratigraphic sequence is part of the OSG, or rather a Paleozoic successor basin.

Stratigraphically above the NBF on the overturned E limb of the ES the base of the sequence currently correlated with the WCG contains distinctive carbonate breccias/conglomerates interbedded with turbidites. The clasts range in size, sorting, and composition, from boulders to sands, angular to sub-rounded constituents, and include micrite, oolitic limestone, pisolitic limestone, oncolite-bearing carbonates, and multigenerational carbonate material. The matrix is composed of mixed quartz and carbonate sands. Mapping and a petrographic study are intended to confirm the NBF assignment on the SE flank of the ES via comparisons with the NBF in the MS. Carbonate units previously assigned to the WCG are being targeted for potential paleontological materials.