CENOZOIC AND YOUNGER TECTONIC ACTIVITY IN SOUTHWESTERN GEORGIA

Cenozoic and younger tectonism has been documented at a number of locations in Southwestern Georgia (Warm Springs, Andersonville, and Thomasville). These structures were identified and delineated principally as a result of detailed mineral resource investigations at Warm Springs and Andersonville or the result of water well investigations (Thomasville). Earlier investigations (Zapp, 1965; Cofer and Manker, 1983) indicate that intermittent movement on the Andersonville Fault affected Paleocene to Holocene age sediments. Maximum vertical displacement is believed to be on the order of 100 feet and down to the north (Zapp, 1965). Deformation and displacement may occupy a zone up to a half-mile wide with the fault being marked by flowage of unconsolidated sediments and flexure and rupture of more indurated beds. Down to the north vertical displacement of Paleocene sediments on the order of 210 feet is suggested on the Warm Springs Fault (White, 1965). Similar displacement of up to 200 feet in Miocene and Oligocene rocks is recorded on the Ochlockonee Fault in Thomasville (Sever, 1966). Because of poor exposure, essentially no detailed mapping, and a paucity of reliable subsurface drill data, the extent of tectonic activity in Southwestern Georgia has been largely unknown. Quadrangle-scale mapping supported by the USGS-sponsored STATEMAP program has recently documented additional faulting, folding, drag folding associated with faulting, dip reversals of up to 60o W, locally extensive, multistage jointing, and local flowage features in Upper Cretaceous to Miocene age sediments. Additional, unmapped structures may be reflected in linear and abrupt changes in the directions of some major streams. Recently reprocessed aeromagnetic data (Daniels, 2001) suggest a number of structural lineaments that may be correlative with some of the major faults. Faulting has had a profound effect on the genesis and preservation of the kaolin and bauxite deposits in the Andersonville and Warm Springs districts. Faulting and folding also may affect groundwater flow patterns and ground water quality.