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MVT Sulfide Mineralization, Carbonate Diagenesis, and Possible Relations to Hydrodynamic Evolution of Delaware Basin, Texas

S. J. Mazzullo

Zinc-lead mineralization in the Sheffield channel is hosted in Early Permian shelf-marginal dolomites adjoining basinal facies, and inner shelf dolomites and evaporites. Sulfur isotopes, fluid inclusions, and burial-geothermal reconstructions suggest emplacement at approximately 96°C during maximum burial in the late Mesozoic to early Tertiary. Sulfide mineralization can be placed into a paragenetic framework that is found in other areas of the Delaware basin. Early syndepositional and postdepositional dolomitization of shelf strata probably resulted from basinward reflux and, perhaps later, from Kohout convection. With progressive burial into the shallow mesogenetic realm, regional fluid-flow patterns reversed as a result of compactional dewatering of basinal shales These fluids affected minor silicification, dolomitization, and dissolution of basinal and shelf-marginal strata. Maximum burial was coincident with (eastward) Laramide tilting of the Delaware basin, which created a gravity-driven flow system that discharged heated fluids to the Sheffield channel area. Sulfide emplacement at this time was accompanied by dissolution of the host dolomites, and late cementation by calcite and dolomite. Similar paragenetic trends recognized elsewhere may suggest regional controls on carbonate diagenesis, porosity history, and hydrocarbon migration related to the hydrodynamic evolution of the Delaware basin.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.