LOWERING OF SEA-LEVEL AS A CAUSE OF THE INITIATION OF DIAPIRISM OF SALT
Published:December 01, 1993
ROBERT EVANS, 1993. "LOWERING OF SEA-LEVEL AS A CAUSE OF THE INITIATION OF DIAPIRISM OF SALT", Rates of Geologic Processes, Tectonics, Sedimentation, Eustasy and Climate–Implications for Hydrocarbon Exploration, John M. Armentrout, Roger Bloch, Hilary C. Olson, Bob F. Perkins
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Many salt-domes evolve from salt-pillows into truly diapiric structures that appear to penetrate thousands of feet of younger sediments, although it is known that the domes grow concurrently with sedimentation. However, none of several suggestions that have been made can explain the onset of diapirism: why salt-structures change from being concordant to discordant.
An examination of twenty-seven domes in the East Texas basin and the North Louisiana basin reveals that the domes broke through their thin overlying cover of shallow-water sediments at times when there was a major lowering of sea-level. The pre-existing salt-pillow formed apositive bathymetric feature that was eroded when exposed as a result of the lowering. The erosion thinned and weakened the cover sufficiently to allow the salt to break through and continue its growth as a diapir concurrently with subsequent sedimentation. For these two basins, there were five major downward excursions of sea-level that allowed diapirism to start during Late Jurassic through Late Cretaceous time, between 135 and 85 m.y.b.p. For any basin characterized by salt-domes, this mechanism should be considered in the evaluation of structural history.