NEW TECTONIC MAP OF THE SOUTHERN AND CENTRAL APPALACHIANS (V. 3.5

A new 1:1,000,000-scale tectonic map of the southern and central Appalachians (SCA) incorporates modern field and structural-stratigraphic, geochronologic (mostly SHRIMP ion microprobe and _Nd), geochemical, and geophysical data to identify crustal boundaries and blocks. Major tectonic units include the ~735 Ma Laurentian failed rift, ~565 Ma rifted margin sedimentary-volcanic assemblage deposited on Grenvillian and pre-Grenvillian crust, the Laurentian platform, and a series of distal Laurentian terranes (Cowrock, Cartoogechaye, Tugaloo-Chopawamsic-Potomac) accreted to Laurentia during the Taconian (Ordovician) or Neoacadian (Late Devonian-Early Carboniferous) orogenies. The Dahlonega gold belt contains Ordovician arc volcanic rocks, but a mixed detrital zircon suite of Laurentian and Gondwanan affinities. The newly recognized Cat Square terrane contains Laurentian, Avalonian, and 430 Ma, detrital zircons, and considered a remnant ocean that closed during Neoacadian accretion of the Carolina superterrane (CST). The Pine Mountain terrane (southernmost exposed Appalachians) consists of Grenvillian basement and a cover sequence bearing Gondwanan detrital zircons. The CST contains numerous Peri-Gondwanan terranes that were deformed, metamorphosed, and amalgamated prior to 530 Ma, then accreted to Laurentia during the Neoacadian along the central Piedmont suture. The Raleigh-Goochland terrane contains blocks of Laurentian basement and cover moved SW (dextrally) out of the collision zone to the N as the Theic ocean closed N to S during the early Alleghanian orogeny. This event also produced the Kiokee–Raleigh belt high-grade metamorphic core in the eastern Piedmont, and NE of the Pine Mountain window. The latter is framed by Alleghanian thrust and dextral faults, formed at different crustal depths (times?). Subsurface components of the SCA are delimited by potential field and limited drill data. The CST extends beneath the Coastal Plain—possibly to the East Coast Magnetic Anomaly (ECMA). The E–W Alleghanian suture with the Suwannee terrane is recognizable to the south beneath Georgia and Alabama in potential field data, truncating all NE–SW-trending Appalachian structures.