Abstract: Pliocene-Pleistocene Structural Characteristics of Central Offshore Louisiana with Emphasis on Growth-Fault Interplay with Salt Tectonics, Gulf of Mexico
Jie Zhang, Joel S. Watkins
Salt distribution, time structure, and isochron maps of central offshore Louisiana were accomplished by tying well data to seismic data. These maps reveal that normal faults, salt diapirs, and intrasalt basins dominate the area. The normal faults are either down-to-the-basin growth faults or counterregional growth faults. The down-to-the-basin growth faults dominate the area. The fault shape on plane view varies along the strike. The western region is controlled by the arcuate down-to-the-basin growth faults. Long linear down-to-the-basin growth faults dominate the central region. A combination of the down-to-the-basin growth faults and counterregional faults characterize the eastern region. These fault groups become progressively younger basinward, which coincide with shelf margin gr wth-fault trends at different times. The listric fault groups sole on salt structures and finally merge on a regional detachment surface, which is believed to be related to once extensive but now largely evacuated salt sheets. A manual reconstruction of a section shows that the system represents the interplay of growth faulting with salt movement and sedimentation, suggesting that salt withdrawal was due to sediment loading, which in turn caused the growth faulting. That is, progradational loading initiates allochthonous salt sheet withdrawal, gravity sliding, and progressive seaward development of growth fault. The formation of growth of faults depresses the sedimentation surface and provides the accommodation space for further sediment loading.
AAPG Search and Discovery Article #90983©1994 GCAGS and Gulf Coast SEPM 44th Annual Meeting, Austin, Texas, October 6-7, 1994