FIELD BASED STRUCTURAL INTERPRETATION OF THE TALLULAH FALLS DOME IN THE SOUTHERN APPALACHIANS

The Tallulah Falls Dome of the Southern Appalachians is located northwest of the terrane bounding Brevard Fault and is associated with rocks of the Eastern Blue Ridge thrust sheet. With a long axis of nearly 25 kilometers the Tallulah Falls Dome is a prominent map-scale geologic feature of the Southern Appalachians. The goal of this project is to document the geometry of the Tallulah Falls Dome and the kinematics associated with dome formation. We have synthesized existing published and unpublished maps of the Tallulah Falls Dome region along with our own field data. Using GIS we are able to explore spatial relationships and structural trends, and construct cross sections to investigate the overall geometry. The Tallulah Falls Dome is cored by the amphibolite grade Tallulah Falls quartzite and muscovite schist and is structurally below the Tallulah Falls Formation, an amphibolite grade meta-sedimentary sequence. Grenville-aged metaplutonic basement gneisses are found near the edges of the dome: both inside and outside. We observe a complex pattern of shear along with slight folding throughout the dome. The dominant lineation is sub-horizontal in the core of the dome but plunges away from the core near the boundary of the dome. The dome displays an axial ratio of 1:1.5 with the long axis parallel to the trend of the orogen. We constructed cross-sections of the Tallulah Falls Dome based on field observations of foliation and bedding. Inferences of dome shape based on foliation are nearly identical to those based on bedding attitudes; we therefore conclude that foliation and bedding are sub-parallel to parallel. This geometric relationship between bedding and foliation implies that the main flattening foliation predates or is coincident with doming.