Pliocene-Pleistocene Structural Characteristics of Central Offshore Louisiana with Emphasis on Growth-Fault Interplay with Salt Tectonics, Gulf of Mexico: ABSTRACT

Abstract

ABSTRACT Interpretation of seismic and well data in central offshore Louisiana reveals that normal faults, salt structures, and intrasalt basins are pervasive and that growth faulting, salt movement, and sedimentation are interrelated processes. Normal faults are either down-to-the-basin growth faults, which dominate the area, or counter-regional growth faults. Fault shape varies along strike in plan view with arcuate down-to-the-basin growth faults characteristic of the western part of the area, and long linear down-to-the-basin growth faults characteristic of the central region. A combination of down-to-the-basin growth faults and counter-regional growth faults characterizes the eastern region. These fault groups usually become progressively younger basinward and coincide with paleoshelf breaks. 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 salt sheets. A conceptual reconstruction of cross sections shows the interplay of growth faulting with salt movement and sedimentation and suggests that salt withdrawal was due to sediment loading, which in turn caused the growth faulting. That is, progradational loading initiates allochthonous salt sheet withdrawal and progressive seaward development of growth faults. The formation of growth faults depresses the sedimentation surface and provides the accommodation space for further sediment loading. Further sediment loading enhances salt withdrawal and growth faulting.