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The Stability of Fe-Mg Chlorites in Hydrothermal Solutions: Ii. Thermodynamic Properties

Published online by Cambridge University Press:  01 January 2024

Stephen U. Aja
Stephen U. Aja*
Affiliation:
Department of Geology, Brooklyn College of the City University of New York, Brooklyn, NY 11210-2889, USA
*
*E-mail address of corresponding author: emenike_nduzo@msn.com
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Abstract

The hydrothermal stabilities of a low-Fe clinochlore and a high-Mg chamosite, in the presence of kaolinite, were investigated recently at T ⩽ 200°C and Pv=PH2O (Aja and Small, 1999; Aja and Dyar, 2002). Standard state thermodynamic properties (S2980, ΔfH1,2980 and ΔfG1,2980) have been obtained for the two chlorites whose structural formulae are (Al2.33Fe1.002+Fe0.143+Ca0.02Mn0.01Ni0.02Cr0.01Mg8.40α0.07) (Si5.66Al2.34)O20(OH)16 and (Fe0.603+Fe5.432+Mg2.30Al2.98Mn0.05Ca0.03Zn0.01α0.60)(Si5.63Al2.37)O20(OH)16. For the low-Fe clinochlore, the respective thermochemical properties are 430 J mol−1 K−1, −8770.64±35.24 kJ mol−1, and −8120.54±32.63 kJ mol−1. ΔfH1,2980, ΔfG1,2980 and S2980, similarly obtained for the Windsor chamosite are −7851.29±23.14 kJ mol−1, −7271.01±21.43 kJ mol−1 and 668±5 J mol−1K−1, respectively. Ideal site-mixing models of chlorite composition, along the chamosite-clinochlore binary, fail to model satisfactorily these chlorite-fluid equilibria only at lower temperatures (T <175°C). The magnitudes of the excess thermodynamic properties calculated for these chlorites, within the ternary clinochlore-daphnite-sudoite system, suggest significant deviations from ideality.

Keywords

ChamositeClinochloreSolid-solutionSudoiteThermodynamic Properties
Type
Research Article
Information
Clays and Clay Minerals , Volume 50 , Issue 5 , October 2002 , pp. 591 - 600
Copyright
Copyright © 2002, The Clay Minerals Society

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References

Aagaard, P. and Helgeson, H.C., (1983) Activity/composition relations among silicates and aqueous solutions: II. Chemical and thermodynamic consequences of ideal mixing of atoms on homological sites in montmorillonites, illites, and mixed-layer clays Clays and Clay Minerals 31 207–217 10.1346/CCMN.1983.0310306.Google Scholar
Aagaard, P. and Jahren, J.S., (1992) Diagenetic illite-chlorite assemblages in arenites. II. Thermodynamic relations Clays and Clay Minerals 40 547–554 10.1346/CCMN.1992.0400508.Google Scholar
Aja, S.U. and Dyar, D.M., (2002) The stability of Fe-Mg chlorites in hydrothermal solutions: I. Results of experimental investigations Applied Geochemistry 17 1219–1239 10.1016/S0883-2927(01)00131-7.Google Scholar
Aja, S.U. and Small, J.S., (1999) The solubility of a low-Fe clinochlore between 25 and 175°C and P v = P H 2 O European Journal of Mineralogy 11 829–842 10.1127/ejm/11/5/0829.Google Scholar
Bailey, S.W. and Bailey, S.W., (1988) Chlorites: structure and crystal chemistry Hydrous Phyllosilicates Washington, D.C. Mineralogical Society of America 347–404 10.1515/9781501508998-015 Reviews in Mineralogy, 19 .Google Scholar
Berman, R.G., (1988) Internally-consistent thermodynamic data set for minerals in the system Na2O-K2O-CaO-MgO-FeO-Fe2O3-Al2O3-SiO2-TiO2-H2O-CO2 Journal of Petrology 29 445–522 10.1093/petrology/29.2.445.Google Scholar
Bird, D.K. and Norton, N.L., (1981) Theoretical prediction of phase relations among aqueous solutions and minerals: Salton Sea geothermal system Geochimica et Cosmochimica Acta 45 1479–1483 10.1016/0016-7037(81)90280-5.Google Scholar
Curtis, C.D., (1985) Clay mineral precipitation and transformation during burial diagenesis Philosophical Transactions of the Royal Society of London A315 91–105 10.1098/rsta.1985.0031.Google Scholar
Helgeson, H.C. and Aagaard, P., (1985) Activity/composition relations among silicates and aqueous solutions: I. Thermodynamics of intrasite mixing and substitutional order/disorder in minerals American Journal of Science 285 769–844 10.2475/ajs.285.9.769.Google Scholar
Holland, T.J.B. and Powell, R., (1990) An enlarged and updated internally consistent thermodynamic dataset with uncertainties and correlations: the system K2O-Na2O-CaO-MgO-MnO-FeO-Fe2O3-Al2O3-TiO2-SiO2-C-H2-O2 Journal of Metamorphic Geology 8 89–124 10.1111/j.1525-1314.1990.tb00458.x.Google Scholar
Holland, T.J.B. and Powell, R., (1996) Thermodynamics of order-disorder in minerals: II. Symmetric formalism applied to solid solutions American Mineralogist 81 1425–1437 10.2138/am-1996-11-1215.Google Scholar
Holland, T.J.B. and Powell, R., (1998) An internally-consistent thermodynamic data set for phases of petrological interest Journal of Metamorphic Geology 16 309–343 10.1111/j.1525-1314.1998.00140.x.Google Scholar
Holland, T. Baker, J. and Powell, R., (1998) Mixing properties and activity-composition relationships of chlorites in the system MgO-Feo-Al2O3-SiO2-H2O European Journal of Mineralogy 10 395–406 10.1127/ejm/10/3/0395.Google Scholar
Hutcheon, I., (1990) Clay-carbonate reactions in the Venture area, Scotian Shelf, Nova Scotia, Canada Geochemical Society Special Publication 2 199 212.Google Scholar
Jahren, J.S. and Aagaard, , (1992) Diagenetic illite-chlorite assemblages in arenites. II. Thermodynamic relations Clays and Clay Minerals 40 547–554 10.1346/CCMN.1992.0400507.Google Scholar
Johnson, J.W. Oelkers, E.H. and Helgeson, H.C., (1992) SUPCRT92: A software package for calculating the standard molar thermodynamic properties of minerals, gases, aqueous species and reactions from 1 to 5000 bars and 0 to 1000°C Computers and Geosciences 18 899–947 10.1016/0098-3004(92)90029-Q.Google Scholar
Kittrick, J.A., (1982) Solubility of two high-Mg and two high-Fe chlorites using multiple equilibria Clays and Clay Minerals 30 167–179 10.1346/CCMN.1982.0300302.Google Scholar
Nordstrom, D.K. and Munoz, J.L., (1994) Geochemical Thermodynamics Boston, Massachusetts Blackwell Scientific Publications. 493 pp.Google Scholar
Robie, R.A. and Hemingway, B.S. (1995) Thermodynamic properties of minerals and related substances at 298.15 K and 1 bar (105 Pascals) pressure and at higher temperatures. United States Geological Survey Bulletin, 2131, 461 pp.Google Scholar
Saccocia, P.J. and Seyfried, W.E. Jr., (1993) A resolution of discrepant thermodynamic properties for chamosite retrieved from experimental and empirical techniques American Mineralogist 78 607 611.Google Scholar
Saccocia, P.J. and Seyfried, W.E. Jr., (1994) The solubility of chlorite solid solutions in 3.2 wt% NaCl fluids from 300–400°C, 500 bars Geochimica et Cosmochimica Acta 58 567–585 10.1016/0016-7037(94)90489-8.Google Scholar
Shock, E.L. and Helgeson, H.C., (1988) Calculation of the thermodynamic and transport properties of aqueous species at high pressures and temperatures: correlation algorithms for ionic species and equation of state predictions to 5 kb and 1000°C Geochimica et Cosmochimica Acta 52 2009–2036 10.1016/0016-7037(88)90181-0.Google Scholar
Stoessell, R.K., (1984) Regular solution site-mixing model for chlorites Clays and Clay Minerals 32 205–212 10.1346/CCMN.1984.0320308.Google Scholar
Vidal, O. Parra, T. and Trottet, F., (2001) A thermodynamic model for Fe-Mg aluminous chlorite using data from phase equilibrium experiments and natural pelitic assemblages in the 100–600°C, 1–25 kb range American Journal of Science 301 557–592 10.2475/ajs.301.6.557.Google Scholar
Walshe, J.L., (1986) A six-component chlorite solid solution model and the conditions of chlorite formation in hydrothermal and geothermal systems Economic Geology 81 681–703 10.2113/gsecongeo.81.3.681.Google Scholar
Welch, M.D. Barras, J.B. and Klinowski, J., (1995) A multinuclear NMR study of clinochlore American Mineralogist 80 441–447 10.2138/am-1995-5-603.Google Scholar
Wiewióra, A. and Weiss, Z., (1990) Crystallochemical classifications of phyllosilicates based on the unified system of projection of chemical composition: II. The chlorite group Clay Minerals 25 83–92 10.1180/claymin.1990.025.1.09.Google Scholar
Wolery, T.J. (1993) EQ3/6, A software package for geochemical modeling of aqueous systems (version 7.2). Lawrence Livermore National Laboratory UCRL-MA 110662.Google Scholar