ROWAN, MARK G.¹, ROBERT A. RATLIFF², JAIME BARCELO-DUARTE³, BRUCE D. TRUDGILL⁴, and PAUL WEIMER^4
1Boulder, CO
²GeoSystems, LLC
³Universidad Nacional Autonoma de Mexico, Mexico City, Mexico
⁴Department of Geological Sciences, University of Colorado, Boulder, CO

Abstract: Emplacement And Evolution Of The Mahogany Salt Body, Central Louisiana Outer Shelf

Interpretation of 3-D and 2-D seismic data shows that the Mahogany salt body is a composite structure comprising a subhorizontal salt tongue, a bulb-shaped salt stock, and an evacuated counter-regional feeder. 3-D structural restoration and analysis of the seismic, well, and biostratigraphic data suggest the following history of salt deformation and associated sedimentation: (1) evacuation of a deep salt sheet into a NW-SE striking, basinward leaning salt wall prior to 47.5 Ma; (2) evacuation of this wall into a narrow stock that inflated and expanded radially in lower to middle bathyal depths between 7.5 and 4.3 Ma, coincident with development of a basinward-thickening depocenter with common ponded and channel facies; (3) gravitational collapse of the bathymetrically elevated salt body, causing southeastward extrusion of a salt tongue and its rafted overburden between 4.3 and 3.65 Ma; (4) tectonic quiescence between 3.65 and 1.95 Ma, when abundant channel sands were deposited in middle bathyal depths; (5) gravity gliding/spreading of the salt and its overburden in middle to upper bathyal depths between 1.95 and 0.5 Ma, resulting in the formation of reactive diapirs, contractional folds and thusts, and strike-slip fault arrays; and (6) active diapirism between 0.5 Ma and the present, as the shelf margin prograded past the Mahogany salt body and continued loading of the salt inflated the footwalls of supra-salt normal faults.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas