A REVIEW OF THE FIELD RELATIONSHIPS AND GEOCHRONOLOGY OF THE CAT SQUARE TERRANE AND THEIR IMPLICATIONS FOR MIDDLE PALEOZOIC ACCRETION OF THE CAROLINA SUPERTERRANE

The Siluro-Dev. Cat Square terrane (CSt) is the only southern Appalachian terrane with a significant peri-Gondawanan provenance. Located in the eastern Inner Piedmont (IP), the CSt extends from NW of Winston-Salem, NC to SW of Griffin, GA and is bound by the Brindle Creek fault (BCf) to the NW, and the central Piedmont suture to the SE. Tectonic models describing the Paleozoic interactions between Laurentia and the Carolina superterrane (Ct) must address several key relationships presented by the CSt: (1) The CSt is juxtaposed over the Tugaloo terrane by the Brindle Creek fault (BCf), which has been traced at a scale of 1:24,000 or greater for ~73 km (~45 mi). The BCf is characterized by a 10–1000 m-wide zone of amphibolite grade mylonite and map-scale truncations, including CSt Dev. granitoids. (2) Syntectonic anatectic Dev. granitoids occur only in the CSt. (3) The CSt consists of metagraywacke, pelitic schist, lesser calc-silicate and amphibolite. Rare ultramafic rocks occur mostly in the eastern CSt, and locally along the BCf. (4) Detrital zircon populations from five CSt samples include a dominance of 1.5–1.0 Ga and 478–435 Ma, minor 629–589 Ma, and rare Paleoproterozoic and Archean zircons. (5) The age of the CSt is bracketed to 435–407 Ma. (6) SHRIMP U-Pb ages of metamorphic zircon indicate the entire IP and the eastern Blue Ridge were affected by the Neoacadian orogeny (365–345 Ma). This event produced the migmatitic, sillimanite and higher-grade core of the IP, the penetrative high-temperature D2 fabrics throughout the IP, and metamorphosed the CSt to sillimanite I and II zones (700–800 ºC, 5–6 kbar). (7) Paleogeographic models for the CSt must consider the large dextral offset (>250 km) associated with the Dev.–Miss. Brevard fault zone. The lithotectonic assemblage and mixed provenance CSt represents the Late Sil. to Dev. remnant Rheic ocean basin between Laurentia and approaching Ct that was closed from NE to SW. Net displacement estimates for the Brevard fault zone and provenance of ~430 Ma zircons support a restored position of the CSt near the PA embayment. This creates key orogen-scale links between the collision of Ct, deformation in the IP, SW migration of the Dev.–Miss. clastic wedge, and possible correlation of the CSt with the Putnam-Nahsoba terrane in New England.