Structure and stratigraphy of Cambro-Ordovician metapelites and carbonates in the Appalachian valley and ridge surrounding Carterville, Georgia.

摘要

The Cartersville area in Georgia lies at the junction between the Alabama Recess and the Tennessee Salient. The rocks here are the easternmost exposures in the foreland fold and thrust belt of the southern Appalachians. It is bounded to the east by the Blue Ridge, the south by the Piedmont and the northwest by the Appalachian Plateau. The lithology of the area is comprised of Cambro-Ordovician metapelites and carbonates that were deposited across the eastern Laurentian continental margin following rifting. Traditional interpretation of the structure of this area is considered to be deformed by a number of thrust fault systems into a duplex structure. Fieldwork and structural analysis of the rocks in this project suggest a regionally overturned tight recumbent folding have taken place. Highly cleaved rocks, stratigraphic reversals and intense deformation in the form of mesoscale folding corroborates to this re-interpretation of the structure of this area. Structural data indicates at least three phases of folding have taken place with one fold phase deforming the structures into a tight overturned recumbent fold and another phase that overprints the earlier one. A total amount of 56% shortening appears to have been accommodated here by the deformation phases. The rocks have undergone sub-greenschist facies metamorphism with the peak metamorphic temperature of about 300°C at ages of about 277+/-7 Ma. The deformational mechanism that conforms to a contractional regime at the corner of a oblique footwall ramp and a transverse footwall ramp also fits well with the reinterpreted structure in this area. The thrust motion across a large, oblique, sinistral, contractional footwall ramp during the compression and telescoping of the late Paleozoic collisional event that resulted in the alignment of thin-skinned transverse structures along the zone of inflection between Appalachian structural salient and recess in Georgia have also affected the rocks in the study area resulting into the complex folding pattern.