--> ABSTRACT: The Role of Salt Tectonics in the Development of Smackover Porosity, Mississippi Salt Basin, by T. A. Trautman and J. J. Morris; #91021 (2010)

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The Role of Salt Tectonics in the Development of Smackover Porosity, Mississippi Salt Basin

TRAUTMAN, TIMOTHY A., and JOHN J. MORRIS

The depositional and diagenetic models, proposed for the Jurassic Smackover Formation, predict that favorable reservoir facies will be developed along the flanks of salt ridges in the interior of the Mississippi Salt Basin. Salt ridge growth played an integral role in reservoir development by providing: (1) sites for localized grainstone deposition, (2) a paleotopographic setting favorable for the development of hypersaline lagoons (source of magnesium for the dolomitization process), and (3) a hydrologic regime favorable for dolomitization (hydraulic head/migration pathways).

Shoaling conditions resulted in the deposition of widespread oolitic grainstones along the northern basin margin. These high-energy facies grade downdip into low-energy carbonate mudstones of the basin interior. Salt-cored bathymetric "highs" provided sites for localized wave-base sedimentation in what regionally was a low-energy basinal setting.

Restricted lower Haynesville "lagoons" formed between the rapidly rising salt ridges. An admixture of subaqueous anhydrite, salt-pans, and micritic limestones comprises the thick sediment "fill" between these prominent salt features. Hypersaline brines, derived from these Haynesville lagoons, permeated downwards "dolomitizing" the underlying Smackover carbonate sediments.

Post-Smackover structural growth provided the hydraulic head necessary for the movement of the "dolomitizing" fluids. Smackover diagenetic patterns reflect the salt ridge orientation; an indication that the fluid movement preferentially followed paleotopography. Intercrystalline porosity as high as 25 percent is developed in the most pervasively dolomitized zones of the Upper Smackover.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.