WATER-ROCK INTERACTION ON ZABARGAD ISLAND, RED-SEA - A CASE-STUDY .1. APPLICATION OF THE CONCEPT OF LOCAL EQUILIBRIUM

被引：24

作者：

SCIUTO, PF

OTTONELLO, G

机构：

[1] Department of Earth Sciences, University of Genova

来源：

GEOCHIMICA ET COSMOCHIMICA ACTA | 1995年 / 59卷 / 11期

关键词：

D O I：

10.1016/0016-7037(95)00100-E

中图分类号：

P3 [地球物理学]; P59 [地球化学];

学科分类号：

0708 ; 070902 ;

摘要：

Zabargad Island is an uplifted fragment of Red Sea lithosphere. The main lithospheric unit of the island is constituted by exceptionally fresh peridotite. Fractured portions of the peridotite bodies, however, locally underwent complex water-rock interactions. We apply a nonlinear minimization routine to study this complex event in the framework of the postulate of local equilibrium in disequilibrium processes (Prigogine, 1955). Such a study allows a rough estimate of the chemistry of interacting fluids (and of P, T conditions at equilibrium). The process took place at an average pressure of 1 kbar and, after an initial hydration stage, a thermal maximum was reached at about 500 degrees C, corresponding to the zone of retrograde formation of olivine gems, after which the temperature progressively fell to about 200 degrees C. Fluids were hypersaline and extremely aggressive (pH = 2-3.5). The composition of the fluids plots in the three-phase region of the H2O-CO2-NaCl system (i.e., an ''aqueous'' liquid coexisting with a CO2-rich gas phase and halite).

引用

页码：2187 / 2206

页数：20

共 55 条

[1]

Aagaard, Helgeson, Thermodynamic and kinetic constraints on reaction rates among minerals and aqueous solutions. l, Theoretical considerations, Amer. J. Sci., 282, pp. 237-285, (1982)

[2]

Barin, Knacke, Kubaschewski, Thermochemical Properties of Inorganic Substances (Supplement), (1983)

[3]

Berner, Early Diagenesis: A Theoretical Approach, (1980)

[4]

Bischoff, Densities of liquids and vapors in boiling NaCI-1420 solutions: A PTVX summary from 300 to 500°C, Amer. J. Sci., 291, pp. 309-338, (1991)

[5]

Bischoff, Seyfried, Hydrothermal chemistry of sea-water from 25 to 350°C, Amer. J. Sci., 278, pp. 838-860, (1978)

[6]

Bonatti, Hamlyn, Ottonello, The upper mantle beneath a young oceanic rift: Peridotites from the Island of Zabargad (Red Sea), Geology, 9, pp. 474-479, (1981)

[7]

Bonatti, Et al., Zabargad (St. John) Island: An uplifted fragment of sub-Red Sea lithosphere, J. Geol. Soc. London, 140, pp. 677-690, (1983)

[8]

Bonatti, Colantuoni, Della Vedova, Taviani, Geology of Red Sea transitional region (22 N-25 N), Oceanol. Acta, 7, pp. 385-398, (1984)

[9]

Bonatti, Ottonello, Hamlyn, Peridotites from island of Zabargad (St John) Red Sea Petrology and Geochemistry, Journal of Geophysical Research, 91 B1, pp. 599-631, (1986)

[10]

Bowers, Helgeson, Calculation of the thermodynamic and geochemical consequences of nonideal mixing in the system H2OCO2NaCI on phase relations in geologic systems: Equation of state for H2OCO2NaCI fluids at high pressures and temperatures, Geochim. Cosmochim. Acia, 47, pp. 1247-1275, (1983)

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