ABSTRACT

Collapse faulting is found circumscribing salt withdrawal basins in the South Louisiana salt dome province. The salt withdrawal basins are the result of unusually large volumes of salt vacating a restricted area of the source salt bed to form peripheral salt intrusions. Such localized salt withdrawal basins are not known in the Upper Gulf coast or interior salt basin because the salt intrusions in those areas are of smaller volume and more widely dispersed. In the Lower Gulf coast a number of areas are found where large intrusions of salt have occurred, or a number of salt domes are found clustered, or a salt ridge of extraordinarily large mass has risen. An abnormally steep sided basin is found associated with the unusually large intrusions of salt.

The sediments overlying the salt withdrawal area have collapsed periodically as salt was withdrawn and moved towards the surface at the periphery of the withdrawal area. The sedimentary collapse caused normal faulting to occur parallel to, and on, the flanks of the newly-initiated basin structure. The faulting, when viewed in cross-section, tends to assume a conical configuration nearly conforming to the cross-sectional outline of the basin. These faults are referred to as collapse faults in this paper.