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Title: Metamorphosed Plio-Pleistocene evaporites and the origins of hypersaline brines in the Salton Sea geothermal system, California: Fluid inclusion evidence

Abstract

The Salton Sea geothermal system (SSGS) occurs in Plio-Pleistocene deltaic-lacustrine-evaporite sediments deposited in the Salton Trough, an active continental rift zone. Temperatures up to 365{degree}C and hypersaline brines with up to 26 wt.% TDS are encountered at 1-3 km depth in the sediments, which are undergoing active greenschist facies hydrothermal metamorphism. Previous models for the origins of the Na-Ca-K-Cl brines have assumed that the high salinities were derived mainly from the downward percolation of cold, dense brines formed by low-temperature dissolution of shallow non-marine evaporites. New drillcores from the central part of the geothermal field contain metamorphosed, bedded evaporites at 1 km depth consisting largely of hornfelsic anhydrite interbedded with anhydrite-cemented solution-collapse shale breccias. Fluid inclusions trapped within the bedded and breccia-cementing anhydrite homogenize at 300{degree}C and contain saline Na-Ca-K-Cl brines. Some of the inclusions contain up to 50 vol.% halite, sylvite and carbonate crystals at room temperature, and some halite crystals persist to above 300{degree}C upon laboratory heating. The data are consistent with the trapping of halite-saturated Na-Ca-K-Cl fluids during hydrothermal metamorphism of the evaporites and accompanying solution collapse of interbedded shales. The authors conclude that many of the slat crystals in inclusions are the residuum of bedded evaporiticmore » salt that was dissolved during metamorphism by heated connate fluids.« less

Authors:
; ;  [1]
  1. Univ. of California, Riverside (USA)
Publication Date:
OSTI Identifier:
5327557
Report Number(s):
CONF-8701162-
Journal ID: ISSN 0016-7037; CODEN: GCACA
DOE Contract Number:  
FG03-85ER13408
Resource Type:
Conference
Journal Name:
Geochimica et Cosmochimica Acta; (USA)
Additional Journal Information:
Journal Volume: 52:5; Conference: American conference on research on fluid inclusions (ACROFI), Socorro, NM (USA), 5 Jan 1987; Journal ID: ISSN 0016-7037
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; 58 GEOSCIENCES; ANHYDRITE; INCLUSIONS; BRINES; FLOW MODELS; CHEMICAL COMPOSITION; SALTON SEA GEOTHERMAL FIELD; ROCK-FLUID INTERACTIONS; CALIFORNIA; DISSOLUTION; DRILL CORES; EVAPORITES; FLUID FLOW; GEOCHEMISTRY; HALITE; HYDROTHERMAL ALTERATION; HYDROTHERMAL SYSTEMS; METAMORPHISM; PLEISTOCENE EPOCH; PLIOCENE EPOCH; RIFT ZONES; SALINITY; ALKALINE EARTH METAL COMPOUNDS; CALCIUM COMPOUNDS; CALCIUM SULFATES; CENOZOIC ERA; CHEMISTRY; ENERGY SYSTEMS; FEDERAL REGION IX; GEOLOGIC AGES; GEOLOGIC STRUCTURES; GEOTHERMAL FIELDS; GEOTHERMAL SYSTEMS; HALIDE MINERALS; MATHEMATICAL MODELS; MINERALS; NORTH AMERICA; OXYGEN COMPOUNDS; QUATERNARY PERIOD; ROCKS; SEDIMENTARY ROCKS; SULFATE MINERALS; SULFATES; SULFUR COMPOUNDS; TERTIARY PERIOD; USA; 152003* - Geothermal Data & Theory- Rock-Water-Gas Interactions; 580000 - Geosciences

Citation Formats

McKibben, M A, Williams, A E, and Okubo, Susumu. Metamorphosed Plio-Pleistocene evaporites and the origins of hypersaline brines in the Salton Sea geothermal system, California: Fluid inclusion evidence. United States: N. p., 1988. Web.
McKibben, M A, Williams, A E, & Okubo, Susumu. Metamorphosed Plio-Pleistocene evaporites and the origins of hypersaline brines in the Salton Sea geothermal system, California: Fluid inclusion evidence. United States.
McKibben, M A, Williams, A E, and Okubo, Susumu. 1988. "Metamorphosed Plio-Pleistocene evaporites and the origins of hypersaline brines in the Salton Sea geothermal system, California: Fluid inclusion evidence". United States.
@article{osti_5327557,
title = {Metamorphosed Plio-Pleistocene evaporites and the origins of hypersaline brines in the Salton Sea geothermal system, California: Fluid inclusion evidence},
author = {McKibben, M A and Williams, A E and Okubo, Susumu},
abstractNote = {The Salton Sea geothermal system (SSGS) occurs in Plio-Pleistocene deltaic-lacustrine-evaporite sediments deposited in the Salton Trough, an active continental rift zone. Temperatures up to 365{degree}C and hypersaline brines with up to 26 wt.% TDS are encountered at 1-3 km depth in the sediments, which are undergoing active greenschist facies hydrothermal metamorphism. Previous models for the origins of the Na-Ca-K-Cl brines have assumed that the high salinities were derived mainly from the downward percolation of cold, dense brines formed by low-temperature dissolution of shallow non-marine evaporites. New drillcores from the central part of the geothermal field contain metamorphosed, bedded evaporites at 1 km depth consisting largely of hornfelsic anhydrite interbedded with anhydrite-cemented solution-collapse shale breccias. Fluid inclusions trapped within the bedded and breccia-cementing anhydrite homogenize at 300{degree}C and contain saline Na-Ca-K-Cl brines. Some of the inclusions contain up to 50 vol.% halite, sylvite and carbonate crystals at room temperature, and some halite crystals persist to above 300{degree}C upon laboratory heating. The data are consistent with the trapping of halite-saturated Na-Ca-K-Cl fluids during hydrothermal metamorphism of the evaporites and accompanying solution collapse of interbedded shales. The authors conclude that many of the slat crystals in inclusions are the residuum of bedded evaporitic salt that was dissolved during metamorphism by heated connate fluids.},
doi = {},
url = {https://www.osti.gov/biblio/5327557}, journal = {Geochimica et Cosmochimica Acta; (USA)},
issn = {0016-7037},
number = ,
volume = 52:5,
place = {United States},
year = {Sun May 01 00:00:00 EDT 1988},
month = {Sun May 01 00:00:00 EDT 1988}
}

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