THE GREAT BALSAM MOUNTAINS WINDOW AND RE-EVALUATION OF THE EXTENT OF THE CHATTAHOOCHEE-HOLLAND MOUNTAIN FAULT

The Great Balsam Mountains window (GBMW) exposes the northeastern extension of the Dahlonega gold belt (DGB) in western North Carolina. It is bound by the Soque River fault to the NW and the Chattahoochee-Holland Mountain (CHM) fault to the SE. The Soque River fault is a postmetamorphic late Taconic(?) fault separating two central Blue Ridge terranes: the upper amphibolite to granulite paragneisses, mafic and ultramafic rocks, pelitic schist and Grenvillian basement of the Cartoogechaye terrane, and the middle to upper amphibolite facies metasedimentary and lesser mafic and ultramafic rocks of the DGB. The CHM fault separates rocks of the DGB from middle to upper amphibolite facies rocks of the Tallulah Falls-Ashe Formation of the Tugaloo terrane in the eastern Blue Ridge. Recent detailed geologic mapping requires re-interpretation of the southern part of the GBMW -— in particular, the location and geometry of the CHM fault. The CHM is a tightly folded postmetamorphic fault, and geochronologic data indicate that it is Alleghanian because it truncates the Rabun Granodiorite (335 Ma) south of the GMBW. Tight folding of the CHM fault and high temperature, axial planar fabrics indicate a late Paleozoic high temperature event affected the Tugaloo terrane and DGB. The northern extension of the Walnut Creek Granodiorite (335 Ma) and an unnamed pluton were also identified in the Tugaloo terrane. In addition, re-evaluation of several lithologic units previously mapped as DGB and Tallulah Falls Formation are now correlated with rocks of the Cartoogechaye terrane. This unit is dominantly composed of muscovite-rich, garnet schist and felsic orthogneiss (Trimont Ridge basement complex(?), 1103 Ma). This correlation moves the Soque River fault eastward where it borders the SW corner of the Great Balsam Mountains window and is truncated by the CHM fault.