Structural Geology of the Northeastern Gulf of Mexico Continental Slope: Observations and Interpretations of Salt Tectonics Based on High Quality Seismic Data and a Robust Stratigraphic Framework

C. J. Travis, I. Stewart, C. A. Yeilding, D. Urban, M. May, E. Ekstrand, K. F. Inman, G. Pfau

Structural studies of the northeastern Gulf of Mexico continental slope were undertaken as part of a subregional, integrated, multidisciplinary analysis which built on earlier BPX studies of the regional hydrocarbon habitat. The dataset included ~1200 mi² of 3D seismic data, as well as 2D data of several vintages. The extensive 3D seismic coverage, relative paucity of salt, and absence of a thick Plio-Pleistocene section result in good imaging down to basement and facilitate construction of a robust stratigraphic framework. These attributes make the area a natural laboratory for the study of salt tectonics. Key geometric relationships are observed, structural evolution can be documented, and structural analogs for less well imaged areas to the west can be compiled.

In Late Jurassic-Cretaceous times, withdrawal basins separated by salt walls formed throughout the study area Subsequent collapse of these early salt bodies and basin inversion progressed from east (Early Cretaceous?) to west (mid-Pliocene), with important local exceptions. Structural styles vary with age of salt wall collapse. For example, widespread emplacement of allochthonous salt sheets was most closely associated with late withdrawal; salt sheet reconstructions indicate that rapid growth correlates with reduced sediment input to the slope. Allochthonous salt was emplaced in various geometries. In some areas, shallow salt sheets were tilted by subsequent, deeper-seated withdrawal. Post-emplacement sediment loading of shallow salt bodies generated suprasalt linked systems of exten ion-contraction-strike-slip. The study area contains examples of salt sheets in various stages of collapse. Finally, results of this study have important implications for regional structural analyses.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995