Paper No. 5
Presentation Time: 2:50 PM
CONFIRMATION OF THE ACADIAN–NEOACADIAN OROGENY DRIVEN BY MID-PALEOZOIC ACCRETION OF THE CAROLINA SUPERTERRANE IN THE SOUTHERN–CENTRAL APPALACHIANS
Until recently, few geologists accepted the idea that the Acadian/Neoacadian orogeny (ANO) had much impact in the southern and central Appalachians (SCA). Detrital and igneous zircon, zircon metamorphic rim, monazite TIMS and ion microprobe ages, and detailed geologic mapping, now provide concrete evidence of the ANO in the SCA. These data, along with N-to-S diachronous clastic wedges (Catskill, Bedford,–. . .–Chattanooga), have provided a difficult-to-refute case for mid–Paleozoic docking of both the Carolina superterrane (Cs) in the SCA, and Gander and Avalon in New England. Almost identical detrital zircon suites in the Tatnic Hill (Putnam-Nashoba terrane) and the Berwick and Hebron Formations (Merrimack synclinorium) in southern New England, and the Cat Square terrane (CSt) in the southern Appalachians, suggest a common provenance. Origin of Siluro-Devonian CSt sediments in a remnant ocean off southern New England, together with kinematic indicators in the Inner Piedmont, suggest Carolina collided obliquely with Laurentian terranes, closed the CSt remnant ocean, and overrode these terranes as far W as the eastern Blue Ridge, forcing SW-directed escape in a tectonically forced orogenic channel. Late Devonian to early Mississippian plutonism (much anatectic) in both the footwall and hanging wall of the Cst, and limited arc plutonism in the Cs hanging wall (e.g., 375 Ma Gladesville Gabbro in GA and Late Devonian Ma Salisbury plutons in NC) related to the small amount of subducted ocean crust, provide additional confirmation of the ANO in the southern Appalachians. Post-Early Silurian faults and folds truncated beneath the 360-Ma Chattanooga Shale unconformity provide additional support for the presence of the ANO in the SCA. Any of these facts taken separately could be suspect, but taken together they constitute a very strong case for the ANO in the SCA related to mid-Paleozoic docking of the Cs to the Laurentian/Taconian Appalachians during the Devonian.