Salt Diapir—Gulf of Mexico
M.T. Sunwall, K.A. McQuillan, C.J. Nick, 1983. "Salt Diapir—Gulf of Mexico", Seismic Expression of Structural Styles: A Picture and Work Atlas. Volume 1–The Layered Earth, Volume 2–Tectonics Of Extensional Provinces, & Volume 3–Tectonics Of Compressional Provinces, A. W. Bally
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This example is representative of piercement salt domes from the Gulf of Mexico, Outer Continental Shelf area. It is located Offshore Louisiana in sediments of Tertiary and Quaternary age. The seismic profile A-A' (Figures 1, 2) illustrates the piercement structure and several important stratigraphic phenomena. This profile trends east to west and is oriented perpendicular to the salt-sediment interface and also perpendicular to the structural strike of the beds. It is worthy to note that the orientation of a seismic profile in this manner is essential to obtaining good quality data over a salt dome.
The most graphic seismic anomaly on the profile is the reflection free zone, between shotpoints 350-400, which contains the salt intrusive (Figure 2). The interpretation of the salt configuration, given in Figure 3, is based on a combination of well control, gravity, reflection, and refraction data.
The faulting associated with the dome is basically of two types consisting of small normal faults on the domal crest and numerous radial faults emanating from the salt perimeter. Though the crestal faults are readily apparent on the A-A' profile the radial faults are difficult to interpret because their strike is identical to that of the seismic line, thus the fault traces parallel the bedding planes.
The stratigraphic thinning, evident in the interval from 1.0 to 2.0 secs (Figure 2), indicates that this dome was a positive structural feature at the time of sediment deposition. Therefore, it is probable that the structural traps around this dome were formed contemporaneous with deposition and thus were in place, able to trap hydrocarbons upon their generation and migration from the basin.