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The AAPG/Datapages Combined Publications Database
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End_Page 352------------------------------
Grand Saline salt dome, Texas, and Winnfield salt dome, Louisiana, have well-developed cap rock on top of them and topographic lows at the surface. In contrast to this, the Five Islands domes of South Louisiana form topographic highs at the surface and give evidence of recent and perhaps fairly rapid movement. Differences in types of fold structure observed in these domes also suggest more recent and rapid movement of the South Louisiana domes. Salt petrofabric patterns indicate that there is a more distinct preferred orientation of salt crystals in the central parts of domes than in their periphery. The relatively stable domes have a more distinct orientation than those that have been subject to Recent differential movement.
The best preferred orientation patterns of salt from Grand Saline are derived from samples taken farthest from the dome margin, and can be related to dodecahedral or cubic gliding of halite if the axial planes of the folds are considered to be the planes of motion. Samples from Winnfield dome show less distinct preferred orientation patterns than those from Grand Saline, but are interpreted as combinations of cubic and dodecahedral gliding or superimposed patterns resulting from successive movements of the salt in different directions. Recent surveying of a water-etch line formed about 27 years ago inside the Winnfield dome when the mine was temporarily flooded show irregularities that may indicate slight differential movement during that interval. Irregular uplift probably tends to b ur or destroy the patterns of preferred orientation that formed during slow unidirectional movement, and distinct petrofabric patterns therefore probably indicate a condition of relative stability.
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