"Origin and Significance of Retrograde Failed Shelf Margins- Tertiary Northern Gulf Coast Basin"
Marc B. Edwards, Marc B. Edwards Consulting Geologists Inc.HGS General Dinner Meeting. April 8, 2002
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Figure One
Features of a typical retrograde failed shelf margin in which slump blocks are a large part of the fill. The most obvious discontinuity is the post-collapse unconformity, but the collapse detachment is equally important. The latter surface has never been exposed at the sea floor, and therefore is a structural rather than stratigraphic feature. Note the possibility for stratigraphic inversion and sub-discontinuity traps.
Figure Two
Features and recognition of slump blocks. Slump blocks occur in clusters or isolated above the collapse unconformity. Blocks are shown as rotated slivers, but may also have a plate-like form. Internally, stratification is parallel rather than divergent. Some wells encounter missing section at both the top and base of the blocks, and shallow water faunas in the blocks are overlain by deepwater faunas in the shales above.
