THE APPALACHIAN PERI-GONDWANAN REALM: A PALEOGEOGRAPHIC PERSPECTIVE FROM THE SOUTH

The Appalachian peri-Gondwanan realm (APGR) is an extensive tract of exotic Neoproterozoic-early Paleozoic crustal blocks that occupies the eastern flank of the orogen. Traditionally, southern Appalachian peri-Gondwanan tracts have been correlated with those of the northern Appalachians on the basis of gross geological similarities. Most paleogeographic reconstructions of the APGR are based on data from the northern Appalachians; consequently in these reconstructions, southern APGR elements are commonly either viewed as being spatially affiliated with those of the north or ignored. However, emerging data from two areally significant southern Appalachian elements, the Smith River allochthon and the Carolina zone, give new insights into the paleogeography of the APGR. The Smith River allochthon is tentatively considered to represent a part of the APGR on the basis of U-Pb monazite and staurolite ages that are compatible with a Gondwanan origin. The allochthon and possibly a substantial portion of adjacent terranes appear to have followed a paleogeographic track independent from any other APGR elements. The Carolina zone, the largest APGR in the southern Appalachians, is recognized as peri-Gondwanan in origin on the basis of its i) geologic evolution, ii) fossil fauna and iii) tectonic history. Mid-Paleozoic regional kinematic patterns suggest that the Carolina zone and its commonly held northern counterpart, the Avalon zone, traveled together on the same lithospheric plate, but their contrasting tectonic histories may indicate that they formed along different margins of this plate. These interpretations lead to a new model for Paleozoic interactions of the APGR with Laurentia.