TURNER, JOSHUA C.¹ and ROWAN, MARK G.^2
1BP Exploration, Houston, TX
²Boulder, CO

Abstract: Geometry and Origin of Salt Eings: Eugene Island 331 Region, Offshore Louisiana

Three-dimensional seismic data are used to document the geometry and evolution of salt wings that occur in a 265 km² area surrounding Eugene Island 331, located on the outer continental shelf 285 km southwest of New Orleans. Salt wings are small, inclined salt bodies that extend up and laterally from highs in the base salt. A regional composite salt canopy in the study area evolved from the merging of three progressively evacuated bulb-shaped salt stocks and a counter-regional ramp. Where salt from the different salt bodies merged, ridges and hinge lines in the base salt resulted. Salt bodies over these highs maintained positive bathymetric expression during passive growth. They subsequently collapsed either due to gravity spreading after depletion of the deeper source layer or due to thin-skinned extension adjacent to the salt bodies ' Sedimentation over the collapsed salt highs caused salt to extrude upward and laterally, back over the original sources, until the salt highs were depleted or sedimentation rates outpaced extrusion rates. Another possible origin for salt-wings is that they could be remnants of evacuated diapirs with flared sides. This mode of emplacement results in younger supra salt-wing sediments than does the progressive emplacement model. Based on age relationships between salt and correlated seismic reflectors, we favor the progressive emplacement model for the study area.

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