Integrated hydrothermal model for proposed deep crustal borehole on Texas Gulf Coast - origins of geopressured brines and lead-zinc, uranium, hydrocarbon, and cap-rock deposits

Conference · Thu May 01 04:00:00 EDT 1986 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:5166684

Light, M P.R.; Posey, H H

Sediment accumulation over Jurassic salt in the Gulf coast has resulted in an interrelated sequential development of salt domes and diagenetic, hydrothermal, and hydrocarbon generation zones. Primary anhydrites within the salt with high /sup 87/Sr//sup 86/Sr ratios suggest early generation of underlying fluids rich in radiogenic strontium that were incorporated in the salt during its diapiric rise to the surface. Subsequently, late-stage, hydrocarbon-rich, saline hydrothermal fluids migrated up the margins of the salt domes, and caused precipitation of several generation of calcite cements, followed by uranium and Mississippi Valley-type lead-zinc-barite deposits near or at salt dome rims. Present fluids in the lower Frio (deeper than 4270 m or 14,000 ft) at the Pleasant Bayou geopressured-geothermal test well (Brazoria County, Texas) are highly saline and enriched in iron, manganese, lead, zinc, and carbon dioxide, and are saturated in methane. These lower Frio waters must have migrated into the area recently because they are not in isotopic equilibrium with diagenetic albite cements formed at temperatures greater than 120/sup 0/C (248/sup 0/F) less than 7.5 million years ago. Isotopic and geochemical data suggest that the fluids trapped by geopressure in the lower Frio at the Pleasant Bayou well are the parent fluids of those causing salt dome cap-rock mineralization.

• Research Organization: Univ. of Texas Bureau of Economic Geology, Austin
• OSTI ID: 5166684
• Report Number(s): CONF-860624-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 70:5
• Country of Publication: United States
• Language: English

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03 NATURAL GAS
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11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
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ORIGIN
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TEXAS
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