J.B. Wanslow, 1983. "Piercement Salt Dome—Upper Continental Slope", 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
Download citation file:
The following seismic section, line B, is located on the upper continental slope, Offshore Louisiana, Gulf of Mexico (see Figure 1). Water depth along the section ranges from 231.6 m (760 ft) on the northwestern end to about 1,115.5 m (2,900 ft) on the southeastern end. Line orientation is approximately N23 W.
To illustrate structural features observed, four seismic horizons were correlated across the dome (see interpreted section). Correlations were done by tracking the horizons around the dome on other seismic lines. A geologic cross section in depth was also prepared. It should be noted that, whereas vertical exaggeration visually is about 2:1 on the seismic sections, no vertical exaggeration is present on the cross section (i.e. the horizontal and vertical scales are the same). The velocity effects of the water were also corrected in the cross section.
The principal structural feature illustrated is a piercement salt dome. The dome is of a somewhat unusual configuration, exhibiting a well-developed shelf area on its northern flank. The strata overlying the crest of the dome are highly disturbed, as is the sea floor, and presumably collapsed in a crestal graben-like configuration. Faults C and D (see interpreted section) represent a major down-to-the-north fault system which intersects the dome. A small fault, B, is present on the northern flank. The southern flank of the salt appears to be nearly vertical. The other main structural feature present on line B is a large down-to-the-south fault, A, thought to be a major growth fault. However, correlation across it is virtually impossible on this line.