USING PETROLOGY TO DETERMINE MORPHOLOGY CONTROLS ON PASSAGE DEVELOPMENT IN RUSSELL CAVE, ALABAMA

Russell Cave, found in the Tennessee, Alabama, and Georgia (TAG) karst region of the eastern United States, was visited for this study. TAG is formed in Mississippian-age limestone and dolostone rocks affected by chemical weathering. Samples were collected from specific passages of Russell Cave in order to determine any geologic controls on passage development and morphology. This project was interested in petrographic characteristics within the carbonate rocks the cave using using thin-section microscopy to examine any facies changes within the carbonate rocks, specifically within various passage morphologies of Russell Cave. A facies change between up-stream and down-stream passages was documented, with the former representing lower-energy depositional conditions, increasing through the meandering passage towards higher-energy depositional conditions. It is unknown if this change in facies results in the corresponding change in passage morphology observed. An increased abundance of petrographic features associated with increased structural influence are documented in the down-stream samples. It is possible that the large meander passage bend between observed in Russell Cave is associated with a structural feature such as a fault in combination with a facies change that produces a lower permeability.