Bennett L. Bearden¹
(1) The University of Alabama, Tuscaloosa, AL

Abstract: The Mobile Area salt basin: Early evolution of salt structures and attendant hydrocarbon trends in offshore Alabama

The eastern Gulf of Mexico region contains numerous underexplored sedimentary offshore basins with a host of siliciclastic and carbonate strata having high potential for hydrocarbon accumulation. The Mobile Area salt basin (MASB), a basinal area that appears to be separate from the Mississippi interior salt basin, is one of the more productive areas in the region having yielded more than 2 Tcf of gas from the Jurassic Norphlet Formation. Salt structures in this basinal area are being studied utilizing 494 miles of 2-D seismic reflection data and selected 3-D seismic data coupled with information from more than 40 test wells. Salt tectonics is the most important process in the geohistory of the MASB and along with attendant listric faulting is responsible for forming the traps. Early evolution of salt structures is observed in the MASB and is documented through time by pillow stage salt features and associated primary peripheral sinks (withdrawal basins or rim synclines). Further south, in Federal OCS waters, salt diapirs and post-diapir stage features are observed on seismic profiles. A simplified model of the downdip progression of structural features of this basinal area was developed which includes updip basement ridge (Wiggins arch complex); updip peripheral listric fault trend coincident with salt termination (Lower Mobile Bay fault trend); low relief salt pillows; salt diapirs; and post-diapir structures. The MASB model is easily transferred to other offshore basins in the eastern Gulf of Mexico as well as to international onshore and offshore rift basins.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana