--> Abstract: DeSoto Canyon Salt Basin: Tectonic Evolution and Salt Structural Styles, by G. Macrae and J. S. Watkins; #90950 (1996).

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Abstract: DeSoto Canyon Salt Basin: Tectonic Evolution and Salt Structural Styles

Grant Macrae, Joel S. Watkins

The early geologic history of the DeSoto Canyon Salt Basin (DSCSB) in the northeastern Gulf of Mexico can be explained by Mesozoic extensional processes associated with a rifted, passively subsiding continental margin. Interpretation of multifold seismic reflection data provide the basis for recognition of an asymmetric Late Triassic-Early Jurassic half graben complex beneath relatively thin, sheet-like, moderately deformed Callovian-age autochthonous salt. Overall geometry of the graben system and observed regional structural trends suggest the DSCSB occurs within an oblique-shear extensional terrane bounded by transfer faults and is consistent with NW-SE rift phase extension during the early Mesozoic opening of the Gulf of Mexico.

The distribution of salt and overlying Upper Jurassic sediments reflect the overall morphology of the basin which was established by Middle Jurassic time following significant attenuation of the crust. Deposition of Lower Cretaceous strata in the central part of the basin was enhanced by local subsidence due to sediment loading. In contrast, Late Cretaceous and Cenozoic sediments reflect uniform deposition in a tectonic setting characterized by subsidence through lithospheric cooling.

Although post-rift sedimentation occurred in a slowly subsiding, stable marginal setting, salt movement and associated growth faulting are the most significant tectonic elements affecting the structural and stratigraphic development of the overlying strata. The earliest record of salt movement is in Oxfordian Smackover interval sediments associated with salt pillows and rollers on the Mississippi-Alabama-Florida shelf. Thickening of expanded sedimentary sections occurs into listric normal growth faults. The Destin Dome anticline, a broad feature on the Florida shelf which attains a maximum thickness in excess of 1.8 km, formed much later than salt structures in the remainder of the basin. Palinspastic reconstruction confirms that differential loading of Lower Cretaceous sediments caus d the salt to migrate updip and landward and form the dome during Late Cretaceous to Early Cenozoic.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas