DELINEATION OF MAP-SCALE TIGHT TO ISOCLINAL F1 FOLD STRUCTURES IN THE HANGING WALL OF THE TALLADEGA THRUST: RESULTS OF MULTIPLE EDMAP PROJECTS ALONG 180KM OF STRIKE LENGTH

The Talladega Belt (TB) in Alabama represents the eastern-most Laurentian continental margin terrane within the region and is composed of predominately metaclastic and metacarbonate units capped by metavolcanics. The lowermost stratigraphy within the TB is the Kahatchee Mountain Group (KMG) that represents early Paleozoic drift facies deposited during opening of Iapetus. The Talladega Group (TG) overlies the KMG along the regional Pre-Lay Dam Unconformity (PLDU), and represents a successor basin sequence related to mid-Paleozoic back-arc extension. Recent mapping funded by the USGS EDMAP program has discovered units of the KMG in the core of a map-scale, overturned to nearly-recumbent, tight to nearly isoclinal anticline. Repetition of KMG units and the PLDU on the flanks of the anticline in the hanging wall of the Talladega-Cartersville thrust fault (TCF) persists over significant portions of the 180 km strike length of the TB in Alabama. EDMAP mapping in the northern extent of the TB includes the 1:24,000 Oak Level, Fruithurst, Piedmont SE, Borden Springs, Alabama 7.5' quadrangles. In this region the hanging wall of the TCF contains a overturned nearly-isoclinal map-scale F1 anticline with axial planar S1 cleavage. Outcrop-scale bedding/cleavage relationships consistently differentiate overturned from upright stratigraphy, therefore, post F1 deformation was not of sufficient intensity to obscure these relationships. 180 km southwest along strike mapping in the Ozan, Shelby, and Bounds Lake, Alabama, quadrangles has delineated a F1 syncline-anticline pair with an amplitude of 6 kilometers and wavelength of 8 kilometers. S1 cleavage is consistently axial planar to these map scale structures.