Calcium chloride brines: The vital component in the hydrothermal brine-hydrothermal ore deposit-evaporite-basinal brine cycle in continental rift basins

Conference · Wed Jan 01 00:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6093304

Hardie, L ^[1]

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1. Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Earth and Planetary Science

Nonmarine evaporites are forming today in chloride-rich saline lakes in a number of arid continental rift and strike-slip basins that are characterized by upwelling of subsurface CaCl[sub 2]-bearing brines driven by forced convection of cool basinal brines or by free convection of hydrothermal brines which reach the surface as brine springs. The compositions of these upwelling brines are distinctively different from that of seawater or typical continental waters due primarily to their high proportion of Ca and low proportion of SO[sub 4]. The most viable explanation for the CaCl[sub 2] composition of these upwelling brines is the interaction between hot convecting groundwaters and bedrock at or above zeolite facies temperatures, as for example occurs in the modern Salton Sea basin. Such upwelling CaCl[sub 2] brines in extensional fault basins can explain the puzzling chemical composition of MgSO[sub 4]-poor potash evaporites, the least understood of all ancient salt deposits. In this regard it is suggested that the following cyclic succession of processes occurs in active continental rift basins during a magmatically-driven thermal event: (1) hydrothermal convection of the ambient porewaters in the rift sediments, (2) dissolution of buried evaporites and hydrothermal metamorphism of the rift sediments, (3) hydrothermal ore deposition in fault-related fractures and within the rift sediments, (4) upwelling brine springs add CaCl[sub 2] and KCl components to the surface lake waters, which on evaporation produce MgSO[sub 4]-poor potash evaporites, (5) decay of the thermal event leads to cool down of the hot brines, which now migrate gravitationally to the deeper parts of the basin to become static Na-Ca-Cl basinal brines.

• OSTI ID: 6093304
• Report Number(s): CONF-921058-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
BASEMENT ROCK
ROCK-FLUID INTERACTIONS
BRINES
GEOCHEMISTRY
GROUND WATER
CALCIUM CHLORIDES
DISSOLUTION
EVAPORITES
HYDROTHERMAL SYSTEMS
MAGNESIUM SULFATES
METAMORPHISM
ORES
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM HALIDES
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
ENERGY SYSTEMS
GEOTHERMAL SYSTEMS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
MAGNESIUM COMPOUNDS
OXYGEN COMPOUNDS
ROCKS
SEDIMENTARY ROCKS
SULFATES
SULFUR COMPOUNDS
WATER
152003* - Geothermal Data & Theory- Rock-Water-Gas Interactions