The continental slope in the northwest Gulf of Mexico ranges in width from 110 km (59 nmi) off the Rio Grande to 240 km (130 nmi) off Louisiana. Throughout its Cenozoic history, this continental margin has increased its limits through the progradation and aggradation of clastic sediments on a broadly downwarped and subsiding basement. Eustatic changes in sea level in response to Pleistocene climatic fluctuations have provided for the deposition of these transgressive and regressive deposits. Rapid Pleistocene sea-level changes are responsible for accelerated deposition and extension of the continental margin.
Lowering of sea level moved nearshore sedimentation to the outer edge of the continental shelf. Shelf outbuilding occurred as deltas prograded over the shelf-slope break. Growth faults cut the sediment column in response to this rapid sedimentation. Marine transgression resulted in a decreased sedimentation rate, depositing a transgressive sequence which capped the regressive clastics. The continental slope in the northwest gulf is further marked by diapiric salt uplifts of variable size.
Correlation of recent high-resolution seismic profiles with drill-core data in a selected location on the outer continental shelf and upper continental slope off the Texas Gulf coast, together with textural, micropaleontologic, and paleomagnetic information and sparker data, yield a history of the late Pleistocene to recent. Analysis of shelf-edge progradation and its relation to sedimentation and structural activity on the continental slope yield additional information with respect to the Pleistocene to recent depositional history.