MIDDLE PALEOZOIC SUCCESSOR BASIN SEQUENCES IN THE SOUTHERN APPALACHIAN WESTERN BLUE RIDGE/TALLADEGA BELT: IMPLICATIONS FOR TECTONIC EVOLUTION

Four structurally isolated, likely middle Paleozoic successor basin sequences (SBS) occur in the southern Appalachian western Blue Ridge/Talladega belt (WBRTB), a composite metamorphic allochthon consisting of three major thrust sheets near the junction of Georgia, North Carolina, and Tennessee. These include: 1) the Maggies Mill Fm. (MMF), which is isolated as fault horses in the Maggies Mill-Citico thrust sheet with no lower or upper stratigraphic boundaries, 2) the structurally overlying Jacks River fm. (JRF) within the core of the Epperson synclinorium (ES), 3) the Mineral Bluff Gp. (MBG) within the core of the Murphy synclinorium (MS) to the SE, and 4) the Talladega Gp. (TG) to the SW. Each SBS is composed of similar but distinct lithfacies, dominated by rhythmites and/or calcareous metaturbidites, locally characterized by olistostromes and polymictic carbonate breccias containing granitic basement clasts. The latter three SBS occur within the main mass of the WBRTB above the Miller Cove fault, stratigraphically above a regionally extensive low-angle unconformity that steps across underlying units (L. Cambrian Chilhowee Gp. to Neoproterozic). Fossil assemblages in 3 of the 4 SBS (TG, JRF, & MMF) constrain their depositional ages to only as old as Silurian-Devonian. The MBG is paleontologically dated as post-Cambrian, but it maps directly along strike into rocks of the TG, and lies unconformably across the same units as the JRF to the NW across the Copper Hill anticline (CHA). The ES and MS share common limbs with the intervening CHA, and are large scale, 1^st generation, NW overturned, tight to isoclinal folds that formed contemporaneously during peak metamorphism (greenschist to upper amphibolite facies) and contain a pervasive regional axial planar foliation. The ES must be middle Paleozoic or younger. The region is marked by a single set of regional metamorphic isograds which overprint the SBS. Finite strain studies above and below the unconformity beneath the JRF and MBG indicate that all units experienced a very similar strain history. The regional metamorphic, structural, and stratigraphic relationships; and unique biostratigraphic constraints characterizing these successor basin sequences suggest a revised tectonic model detailing the evolution of these post-Taconic sequences.