ALONG STRIKE TRUNCATION OF A MEGASCOPIC RECLINED ANTICLINE IN THE HANGING WALL OF THE TALLADEGA-CARTERSVILLE FAULT: PIEDMONT SE AND JACKSONVILLE EAST QUADRANGLES, AL

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 megascopic reclined anticline, and repetition of TG units and the PLDU on the flanks of the fold in the Piedmont SE, AL 7.5' quadrangle. The megascopic structure controlling the distribution of these units consists of an overturned, northwest verging, reclined, closed anticline cored by the Waxahatchee slate formation, the basal unit in the KMG. Southeast of the axial trace of the anticline, the overlying Brewer and Wash Creek formations are exposed and overlain unconformably by units of the TG. Northwest of the axial trace units of the KMG and TG are overturned based on bedding/cleavage relations, and primary features. The overturned limb of the megascopic anticline composes the immediate hanging wall of the Talladega thrust in this portion of the Talladega Belt, and is truncated by the fault along strike to the southwest in the adjacent Jacksonville East quadrangle. The megascopic fold structure is interpreted to by syn-metamorphic because of axial planar S1 cleavage, and it pre-dates the Talladega-Cartersville Thrust that truncates the axial surface and limbs of the fold at depth.