Southeastern Section - 54th Annual Meeting (March 17–18, 2005)

Paper No. 9
Presentation Time: 1:00 PM-5:00 PM


VANCE, R. Kelly, HOWELL, Susan and JONES, Martin, Department of Geology and Geography, Georgia Southern Univ, P.O. Box 8149, Statesboro, GA 30460,

Geologic mapping was conducted at a 1:24000 scale along the northwest side of the inundated Little River valley of Georgia in the Woodlawn and Aonia quadrangles, between the Modoc zone and the Charlotte belt. Resulting geologic maps were converted into digital images for use in ArcGIS. The GIS data base includes sample points, structural, petrographic and geochemical data. The map covers Neoproterozoic to Cambrian greenschist facies rocks of the Carolina slate belt previously assigned to the volcanic dominated Persimmon Fork Formation and mudstone dominated Richtex Formation. The dominant regional rock fabric is a foliation striking N 55-70o E, dipping 30-70o NW. Small folds in the southeast portion of the Aonia Quadrangle display a N 50o E axial trend plunging NE at 15o. Intermediate to felsic subaqueous tuffs and coarse volcaniclastic rocks are interlayered with increasing proportions of greenstones, greywacke and mudstones toward the southeast. Thin beds of uniform, fine-grained siliceous rocks between the pyroclastic flows and sedimentary rocks may be the submarine equivalent of surge or airfall deposits. Graywacke beds grading upward to fine sands and laminated mudstones with local convoluted bedding, probably originated as submarine fans. Graded bedding and cross-bedding indicate northeast and northwest tops, respectively, as relict bedding changes from a dominant N 70-85o W strike dipping 55-65o NE in the Aonia Quad to a dominant N 70-85o E strike with 50-74o dips to the NW in the central Woodlawn Quad suggesting a N-NE trending regional syncline. The entire succession is interpreted as interfingering between inner distal, mudstone-dominated deep water facies and a proximal facies dominated by pyroclastic rocks and coarse volcaniclastic deposits. Greenstones interlayered with the tuffs and mudstones represent mafic lava, volcaniclastic rocks, dikes and sills. The presence of mafic rocks and local sulfide mineralization in this transition zone favors an intra-arc basin produced by arc extension.