Salt Control on Sedimentary Processes in Early Pleistocene: Ship Shoal South Addition Blocks 349-358, Gulf of Mexico.

摘要

The interpretation of 3D seismic data from Ship Shoal South Addition Blocks 349-358, Gulf of Mexico shows a complex interaction between salt, faults, and sedimentary strata.Reconstruction of the geometry of early Pliestocene (about 3.65 Ma) through recent salt and associated sediments reveals the evolution of a supralobal basin in the study area. The basin depocenter shifted from the northeastern part to the center of the study area through time. A small, bulb-shaped, salt-stock structure occurs in the northwest, and a salt sheet structure is present in the southeastern part of the study area. Those structures are part of a pennant-shaped structure bounded by counter regional faults trending northeastward.Salt movements created instability and triggered extensive faulting of the overlying strata. Three-dimensional reconstruction suggests that salt blocked the sediment during the early Pleistocene. The sediment was diverted around the salt high on both east and west sides of the salt body to the southwest and southeast.Stratigraphic interpretation of the interval between 1.35 Ma and 1.95 Ma led to the identification of a highstand systems tract (HST), a transgressive systems tract(TST), and two lowstand systems tracts (LST). The strata are developed normally in the depocenter area, whereas the strata at the basin margin were deformed by salt movement and faulting.Each systems tract is uniquely associated with a certain seismic facies. Three seismic facies were identified associated with LST, TST, and HST. Additionally, seismic sections reveal channel geometries in the LST. Seismic attribute analysis elucidates facies distribution in the systems tracts.Because of its ability to move, to divert sediment, to create instability, and to block sediment transport pathways, salt exercises the main control on the sedimentary processes in the study area.