A model for the evolution of brines in salt from the lower Salado Formation, southeastern New Mexico
- Sandia National Laboratories, Albuquerque, NM (USA)
Fluid inclusions were collected from a bedded salt horizon in the lower Permian Salado Formation in the Delaware Basin, southeastern New Mexico. The sampling horizon, at a depth of approximately 645 meters, consists primarily of recrystallized halite, with thin layers of anhydrite. Other trace minerals, dispersed throughout the salt, include quartz, polyhalite, gypsum, K-feldspar, magnesite, and clays. The chemistry of the inclusion fluids and the associated mineralogy suggest that these brines represent Permian seawater that has undergone evaporation and subsequent modification by diagenetic reactions, dominated by the alteration of calcium sulfate to polyhalite and magnesite formation. The range of fluid inclusion compositions suggests a significant departure from a simple seawater evaporation model. Other brines from the same horizon in the Salado Formation were sampled and analyzed for the same elements as the fluid inclusions, and differed significantly from them primarily by the depletion of Mg relative to K. The association of these brines with argillaceous and/or anhydritic halite containing a suite of authigenic minerals (quartz, magnesite, and Mg-rich clays) suggests that these are intergranular brines with compositions determined over a much longer time scale than that required by the fluid inclusions. The principal reactions affecting intergranular brine chemistry are dehydration of gypsum, dewatering of detrital clays, and uptake of Mg during clay diagenesis. Overall, the observed variation in brine compositions implies that, if large-scale hydrologic circulation is occurring in the Salado halite, the time scale is limited by the rate required for low-temperature silicate diagenesis.
- OSTI ID:
- 5152687
- Report Number(s):
- CONF-8701162--
- Journal Information:
- Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:5; ISSN GCACA; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
Similar Records
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Related Subjects
580000* -- Geosciences
ABUNDANCE
ALKALI METALS
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
ANHYDRITE
BRINES
BROMINE
CALCIUM
CALCIUM COMPOUNDS
CALCIUM SULFATES
CHEMICAL COMPOSITION
CHEMISTRY
CHLORINE
DIAGENESIS
ELEMENT ABUNDANCE
ELEMENTS
FEDERAL REGION VI
GEOCHEMISTRY
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
HALIDE MINERALS
HALITE
HALOGENS
INCLUSIONS
MAGNESIUM
METALS
MINERALOGY
MINERALS
NEW MEXICO
NONMETALS
NORTH AMERICA
OXYGEN COMPOUNDS
POTASSIUM
RECRYSTALLIZATION
SALT DEPOSITS
SEDIMENTARY BASINS
SODIUM
SULFATE MINERALS
SULFATES
SULFUR COMPOUNDS
USA