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LEONARD, CLIFFORD, JR., and ROBERT R. PHILLIPS, SR., Accipiter, Marietta, CA

ABSTRACT: Tectonic Boundaries of the Eastern Gulf Coast of North America

Two Precambrian extensional fault episodes, recorded in mapping from central Arkansas across Mississippi, central Alabama, southern Georgia, and into the Atlantic Ocean affected later Pennsylvanian and Triassic tectonics. This interpretation is from magnetic anomaly data and is supported by seismic, gravity, core, and well-log data. The fault system was first suspected from an anomalous magnetic high, representing a feature that affected tectonism during the Ouachita and the Alleghenian orogenies of the eastern Gulf Coast and southeastern United States. The northernmost upthrown block is considered part of an ancient passive continental margin developed during the late Precambrian. The southern downthrown block is deformed by left-lateral transverse faults active during the Ouachita O ogeny. The Ouachita Orogeny may have deformed terrain farther east than the Black Warrior basin. These transverse fault blocks were buttressed by the footwall of the extensional fault system. These left-lateral faults were again displaced by later right-lateral Alleghenian wrench faults extending from Florida and Georgia into Alabama, Mississippi, and southern Arkansas.

AAPG Search and Discovery Article #90989©1993 GCAGS and Gulf Coast SEPM 43rd Annual Meeting, Shreveport, Louisiana, October 20-22, 1993.