Active metasomatism in the Cerro Prieto geothermal system, Baja California, Mexico: a telescoped low-pressure, low-temperature metamorphic facies series
In the Cerro Prieto geothermal field, carbonate-cemented, quartzofeldspathic sediments of the Colorado River delta are being actively metasomatized into calc-silicate metamorphic rocks by reaction with alkali chloride brines between 200 and 370 C, at low fluid and lithostatic pressures and low oxygen fugacities. Their petrologic investigations of drill cores and cuttings from more than 50 wells in this field identified a prograde series of zones that include as index minerals wairakite, epidote, prehnite, and clinopyroxene. Associated divariant mineral assemblages are indicate of a very low pressure, low-temperature metamorphic facies series spanning the clay-carbonate, zeolite, greenschist, and amphibolite facies. This hydrothermal facies series, which is now recognized in other active geothermal systems, is characterized by temperature-telescoped dehydration and decarbonation. Its equivalent can now be sought in fossil hydrothermal systems.
- Research Organization:
- Univ. of California, Davis
- OSTI ID:
- 7057152
- Journal Information:
- Geology; (United States), Vol. 12:1
- Country of Publication:
- United States
- Language:
- English
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