Print this pageOrigin and Evolution of Secondary Salt Welds, Southern Additions, Offshore Louisiana
HALL, DAVID J:, KENNETH J. THIES and BRUCE E. BOWEN
Interpretation and mapping of more than 15,000 km of 80-fold recent seismic data throughout the south additions has revealed the widespread presence of steeply-dipping secondary salt welds associated with Miocene and Pliocene slope basin sedimentation and deformation. The welds trend generally north-northeast, nearly perpendicular to the Miocene shelf edge, and can be traced directly into current salt walls and salt massifs in Green canyon and Garden Banks. Back-stripping of a network of depth-converted seismic lines demonstrates that the welds probably originate as passive structures in connection with down-building and ductile salt flow. Back-stripping of simplified models of slope basins and salt walls suggests that no compressive shortening is required to explain the geometry, though some shortening cannot be eliminated because unknown quantities of salt have flowed through the system. In general, basin subsidence, simple down-building and gravity spreading coupled with normal processes of turbidite slope sedimentation can be shown to account for observed geometries throughout the south additions with no attendant room problem. We suggest the sub-salt and sub-weld play structures are largely the accumulated result of currently observable processes in the modern slope.