SEISMIC INTERPRETATION AND STRUCTURAL VALIDATION OF THE ROME AND COOSA THRUST FAULTS, NORTHWEST GEORGIA

The Alleghenian Orogeny of the late Paleozoic was the result of collision between the Laurentia and Gondwana paleo-continents, and is responsible for the structural deformation of Cambrian to Pennsylvanian age sedimentary strata within the Appalachian valley and ridge province. The aim of this project is to determine the subsurface geology of the southern Appalachian fold and thrust belt along a west-northwest trending profile in northeastern Alabama and northwestern Georgia. The study area crosses a vast majority of the valley and ridge, bounded to the southeast by the Blue Ridge metamorphic province and to the northwest by the Cumberland Plateau. The region is characterized by low angle detachment of Paleozoic thrust sheets sloping from ~8,000 feet to ~10,000 feet to the southeast.

Seismic interpretation has been conducted on the two way travel time section, with surface geology, seismic reflectors, and well log ties providing the basis for formation boundary and fault identification. The focus for this presentation will be the interaction of the Rome and Coosa Faults, seismic interpretation of a duplex below the Rome Fault, and implications to the formation of anticlines at the leading edge of the Paleozoic thrust sheets. The Coosa Fault is the only thrust in the region which brings Cambrian Rome Formation to the surface along this seismic line, and appears to have displaced this lower portion of Paleozoic strata a significant distance from the east. The Coosa Fault may be the roof thrust of the aforementioned duplex, which consists of several horses of Cambrian Rome and Conasauga Formations, and is analogous along strike to a similar surface structure to the southwest. The Rome Fault, which predates the Coosa Fault, is a sub-horizontal thrust that has been uplifted and eroded in the hanging wall of the Coosa Fault.

The seismic interpretation and determination of timing of these thrusts should provide insight regarding the development of the duplex and fault-related folds in the Valley and Ridge. The resultant seismic interpretation is then converted to depth, and balancing and restoration of the depth-converted cross section will then be used to structurally validate the final geologic interpretation.