Salt tectonics and sequence stratigraphy of central offshore Louisana, Gulf of Mexico

Integrated seismic and well data interpretation and mapping in the central offshore Louisiana show that salt tectonics, growth faulting and sedimentation are inter-related processes. Six types of salt structures have been identified in the area: salt pillows, rollers, ridges, pods, sheets, and stocks. Salt withdrawal results in five types of sedimentary basins. Developments of intrasalt basins include a slope, shelf-edge, and shelf stage. Salt sheets are primary allochthonous salt bodies formed by combined vertical and horizontal movement of autochthonous salt, i.e., the Louann salt pierced upper Jurassic and lower Miocene strata and then intruded laterally into middle and upper Miocene sediments. Differential sediment loading is the major driving forces for salt movement in the area.; Normal faults are either down-to-the-basin growth faults, or counter-regional growth faults. Fault shape varies along strike in plan-view. Fault groups usually become progressively younger basinward and coincide with paleoshelf breaks while active. Listric faults sole onto salt structures or merge with regional detachment surfaces that are believed to be related to once extensive but now largely evacuated allochthonous salt sheets. Progradational loading initiates allochthonous salt sheet withdrawal and progressive seaward development of growth faults.; Isochron maximas correspond to the depocenters that are closely related to sedimentary fairways and paleoshelf breaks. The isochron patterns show that deposenters and sediment fairways shifted during Plio-Pleistocene. The integration of major growth fault trends, isochron maxima, increased regional dip, and the outer neritic to upper bathyal paleoecologic zones shows the paleoshelf edge prograded seaward during Plio-Pleistocene.; The present outer shelf and upper slope, central offshore Louisiana was a slope environment characterized by six major intrasalt basins during the deposition of Plio-Pleistocene sediments. I have identified nine 4th order sequences in the section by integration of seismic, well log, and nannofossil data. The seismic and well log characteristics vary from sequence to sequence, between systems tracts, as well as from structural highs to salt withdrawal basins. Lowstand sediments onlap flanks of salt structures and consist of sand-prone portion of sequences. Transgressive systems tracts, highstand systems tracts, and partial progradational wedges may locally drape the top of salt structures. A new sequence stratigraphic model that includes salt tectonics, growth faulting and refined systems tract terminology developed for the study area may play an important rule in future petroleum exploration and development in this region.