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Clay Mineral Thermometry—A Critical Perspective

Published online by Cambridge University Press:  28 February 2024

E. J. Essene  and
D. R. Peacor
E. J. Essene
Affiliation:
Department of Geological Sciences, The University of Michigan, Ann Arbor Michigan 48109-1063
D. R. Peacor
Affiliation:
Department of Geological Sciences, The University of Michigan, Ann Arbor Michigan 48109-1063
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Abstract

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Diagenetic clay minerals usually occur as heterogeneous assemblages of submicroscopic layers consisting of different structure types such as illite, smectite and chlorite, with variable composition within a given structure type, and with highly variable concentrations of imperfections. The dimensions of mixed-layering, the semi-coherent to coherent nature of the structures across the layering, and compositional heterogeneity occur at a scale well below that of an individual thermodynamic phase. These relations imply that most clays are not distinct minerals or phases, and that assemblages of clays in shales and mudstones are incompatible with the phase rule. Such relations are better evaluated in terms of the formation of metastable materials with each small unit having unique chemical properties, rather than as a small number of stable homogeneous phases. Consequently, treatment of most clay minerals in terms of equilibrium stability with either a thermodynamic or experimental approach is subject to error.

Chemical reactions involving most clay minerals are best understood with kinetic models. These involve a great variety of parameters such as time, fluid/rock ratio, deformation history, nature of starting materials and transformation mechanisms, as well as the variables, such as temperature, pressure and composition, that are commonly used to define equilibrium. Solubility experiments on the stabilities of clay minerals are unlikely to attain equilibrium at low temperatures. Moreover, the activity of soluble species may be controlled by surface equilibria, or by absorbed or exchangeable cations. Interpretations of available experiments on the solubility of illite vs. other mineral assemblages are in violation of Schreinemakers’ rules and indicate lack of equilibrium.

Predictable sequences of clay minerals as a function of temperature are best understood through the Ostwald step rule, in which clay mineral assemblages undergo reactions in response to kinetic factors that represent reaction progress rather than an approach to equilibrium. Currently used clay mineral thermometers (illite crystallinity, smectite/illite reaction, chlorite composition) are not based on equilibrium reactions. Such systems are not accurate thermometers and therefore have questionable utility.

Keywords

Chlorite thermometryClay thermometryIllite crystallinityIllite solubilityMetastabilityOstwald step ruleSmectite solubilityStability
Type
Research Article
Information
Clays and Clay Minerals , Volume 43 , Issue 5 , October 1995 , pp. 540 - 553
Copyright
Copyright © 1995, The Clay Minerals Society

Footnotes

1

Contr. No. 503 from the Mineralogical Laboratory, Dept. Geological Sciences, Univ. Michigan.

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 & Clay Miner. 31: 207–217.Google Scholar
Aagaard, P., and Jahren, J. S. 1992. Diagenetic illite-chlorite assemblages in arenites. II. Thermodynamic relations. Clays & Clay Miner. 40: 547–554.CrossRefGoogle Scholar
Ahn, J.-H., Peacor, D. R., and Coombs, D. S. 1988. Formation mechanisms of illite, chlorite and mixed-layer illite-chlorite in Triassic volcanogenic sediments from the Southland syncline, New Zealand. Contr. Miner. Petrol. 99: 82–89.Google Scholar
Aja, S. U., 1989. A hydrothermal study of illite stability relationships between 25° and 250°C and Pv = PH2O: PhD thesis, Washington St. Univ., 190 pp.Google Scholar
Aja, S. U., 1991. Illite equilibria in solutions: III. A reinterpretation of the data of Sass et al (1987): Geochim. Cosmochim. Acta 55: 3431–3435.CrossRefGoogle Scholar
Aja, S. U., and Rosenberg, P. E. 1992. The thermodynamic status of compositionally variable clay minerals: a discussion. Clays & Clay Miner. 40: 292–299.Google Scholar
Aja, S. U., Rosenberg, P. E., and Kittrick, J. A. 1991a. Illite equilibria in solutions: I. Phase relationships in the system K2O-Al2O3-SiO2-H2O between 25° and 250°C. Geochim. Cosmochim. Acta 55: 1353–1364.Google Scholar
Aja, S. U., Rosenberg, P. E., and Kittrick, J. A. 1991b. Illite equilibria in solutions: II. Phase relationships in the system K2O-MgO-Al2O3-SiO2-H2O between 25° and 250°C. Geochim. Cosmochim. Acta 55: 1365–1374.CrossRefGoogle Scholar
Anovitz, L. M., Perkins, D., and Essene, E. J. 1991. Meta-stability in near-surface rocks of minerals in the system Al2O3-SiO2-H2O. Clays & Clay Miner. 39: 225–233.Google Scholar
Awwiller, D. N., 1993. Illite/smectite formation and potassium mass transfer during burial diagenesis of mudrocks. J. Sed. Petrol. 63: 501–512.Google Scholar
Bethke, C. M., and Altaner, S. P. 1986. Layer-by-layer mechanism of smectite illitization and application to new rate law. Clays & Clay Miner. 34: 146–154.Google Scholar
Bish, D. L., and Aronson, J. L. 1993. Paleogeothermal and paleohydrologic conditions in silicic tuff from Yucca Mountain, Nevada. Clays & Clay Miner. 41: 148–161.Google Scholar
Boles, J. R., and Franks, S. G. 1979. Clay diagenesis in the Wilcox sandstones of southwest Texas: implications of smectite diagenesis on sandstone cementation. J. Sed. Petrol. 49: 55–70.Google Scholar
Buatier, M., Peacor, D. R., and O'Neil, J. R. 1992. Smectite-illite transition in Barbados accretionary wedge sediments. TEM and AEM evidence for dissolution/crystallization at low temperature. Clays & Clay Miner. 40: 65–80.Google Scholar
Burst, J. F., 1969. Diagenesis of Gulf Coast clayey sediments and its possible relation to petroleum migration. AAPG Bull. 53: 73–93.Google Scholar
Cathelineau, M., 1988. Cation site occupancy in chlorites and illites as a function of temperature. Clay Miner. 23: 471–485.Google Scholar
Cathelineau, M., and Nieva, D. 1985. A chlorite solid solution geothermometer. The Los Azufres (Mexico) geo-thermal system. Contr. Miner. Petrol. 91: 235–244.Google Scholar
Chermak, J. A., and Rimstidt, J. D. 1989. Estimating thermodynamic properties (ΔG°f and ΔH°f) of silicate minerals from the sum of polyhedral contributions. Am. Miner. 74: 1023–1031.Google Scholar
Chernov, A. A., and Lewis, J. 1967. Computer model of crystallization of binary systems: kinetic phase transitions. J. Phys. Chem. Solids 28: 2185–2198.Google Scholar
Cho, M., and Fawcett, J. J. 1986. A kinetic study of clinochlore and its high temperature equivalent forsterite-cordierite-spinel at 2 kbar water pressure. Am. Miner. 71: 68–77.Google Scholar
de Caritat, P., Hutcheon, I., and Walshe, J. L. 1993. Chlorite geothermometry: A review. Clays & Clay Miner. 41: 219–239.Google Scholar
Eberl, D. D., 1993. Three zones for illite formation during burial diagenesis and metamorphism. Clays & Clay Miner. 41: 26–37.Google Scholar
Eberl, D. D., Srodon, J., Kralik, M., Taylor, B. E., and Peterman, Z. E. 1990. Ostwald ripening of clays and meta-morphic minerals. Science 248: 474–477.CrossRefGoogle Scholar
Essene, E. J., 1982. Geologic thermometry and barometry. In Characterization of Metamorphism through Mineral Equilibria. Ferry, J. M., ed. Rev Miner. 10: 153–206.Google Scholar
Essene, E. J., 1989. Update on geologic thermobarometry. In Evolution of Metamorphic Belts. Daly, J. S., Cliff, R. A., and Yardley, B. W. D., eds. Geol. Soc. Spec. Pub. 43: 1–44.Google Scholar
Essene, E. J., Anovitz, L. M., and Perkins, D. 1994. Mineral metastability in the system Al2O3-SiO2-H2O. a reply. Clays & Clay Miner. 42: 102–105.Google Scholar
Fawcett, J. J., and Yoder, H. S. 1966. Phase relations of the chlorites in the system MgO-Al2O3-SiO2-H2O. Am. Miner. 51: 353–380.Google Scholar
Ferry, J. M., 1986. Reaction progress: a monitor of fluid-rock interaction during metamorphic and hydrothermal events. In Fluid-Rock Interactions during Metamorphism. Walther, J. V., and Wood, B. J., eds. NY: Springer-Verlag, 60–88.CrossRefGoogle Scholar
Fleming, P. D., and Fawcett, J. J. 1976. Upper stability of chlorite + quartz in the system MgO-FeO-Al2O3-SiO2-H2O at 2 kb water pressure. Am. Miner. 61: 1175–1193.Google Scholar
Frey, M., 1987. Low Temperature Metamorphism, Glasgow: Blackie, 351 pp.Google Scholar
Frey, M., Capitani, C. de, and Liou, J. G. 1991. A new petrogenetic grid for low grade metabasites. J. Metam. Geol. 9: 497–509.Google Scholar
Fyfe, W. S., 1960. Hydrothermal synthesis and determination of equilibrium between minerals in the subliquidus region. J. Geol. 68: 553–566.Google Scholar
Fyfe, W. S., Turner, F. J., and Verhoogen, J. 1958. Metamorphic Reactions and Metamorphic Facies, Geol. Soc. Amer. Mem. 73: 259 pp.Google Scholar
Garrels, R. M., 1984. Montmorillonite/illite stability diagrams. Clays & Clay Miner. 32: 161–166.Google Scholar
Hemley, J. J., Marinenko, J. W., and Luce, R. W. 1980. Equilibria in the system Al2O3-SiO2-H2O and some implications for alteration/mineralization processes. Econ. Geol. 75: 210–228.Google Scholar
Hillier, S., 1993. Origin, diagenesis and mineralogy of chlorite minerals in Devonian lacustrine mudrocks, Orcadian Basin, Scotland. Clays & Clay Miner. 41: 240–259.Google Scholar
Hoffman, J., and Hower, J. 1979. Clay mineral assemblages as low grade metamorphic geothermometer—Application to the thrust faulted disturbed belt of Montana. In Aspects of Diagenesis. Scholle, P. A., and Schluger, P. S., eds. SEPM Spec. Pub. 26: 55–79.Google Scholar
Hower, J., and Altaner, S. P. 1983. The petrologic significance of illite/smectite. Prog. Abstr., 20th Ann. Meeting, Clay Min. Soc., Buffalo NY, 40 pp.Google Scholar
Hower, J., Eslinger, E. V., Hower, M. E., and Perry, E. A. 1976. Mechanism of burial metamorphism of argillaceous sediments: I. Mineralogical and chemical evidence. Geol. Soc. Am. Bull. 87: 725–737.2.0.CO;2>CrossRefGoogle Scholar
Huang, W.-L., Longo, J. M., and Pevear, D. R. 1993. An experimentally derived kinetic model for smectite-to-illite conversion and its use as a geothermometer. Clays & Clay Miner. 41: 162–177.Google Scholar
Itaya, T., 1981. Carbonaceous material in pelitic schists of the Sanbagawa metamorphic belt in Central Shikoku, Japan. Lithos. 14: 215–224.CrossRefGoogle Scholar
Jahren, J. S., and Aagaard, P. 1992. Diagenetic illite-chlorite assemblages in arenites. I. Chemical evolution. Clays & Clay Miner. 40: 540–546.Google Scholar
Jiang, W.-T., Peacor, D. R., and Buseck, P. R. 1994c. Chlorite geothermometry? Analytical contamination and apparent octahedral vacancies. Clays & Clay Miner. 42: 593–605.CrossRefGoogle Scholar
Jiang, W.-T., Peacor, D. R., and Essene, E. J. 1990a. Transmission electron microscopic study of coexisting pyro-phyllite and muscovite: direct evidence for the metastability of illite. Clays & Clay Miner. 38: 225–240.Google Scholar
Jiang, W.-T., Peacor, D. R., and Essene, E. J. 1994a. Analytical and transmission electron microscopic study of clay minerals in sandstone of Kettleman North Dome, California: implications for the metastability of illite. Clays & Clay Miner. 42: 35–45.Google Scholar
Jiang, W.-T., Peacor, D. R., Merriman, R. J., and Roberts, B. 1990b. Transmission and analytical electron microscopic study of mixed-layer illite/smectite formed as an apparent replacement product of diagenetic illite. Clays & Clay Miner. 38: 449–468.Google Scholar
Kisch, H. J., 1981. Coal rank and illite crystallinity associated with the zeolite facies of Southland and the pumpellyite-bearing facies of Otago, southern New Zealand. New Zeal. J. Geol. Geophys. 24: 349–360.Google Scholar
Kisch, H. J., 1983. Mineralogy and petrology of burial diagenesis (burial metamorphism) and incipient metamorphism in clastic rocks. In Diagenesis in Sediments and Sedimentary Rocks 2. Larsen, G., and Chilingar, G. V., eds. New York: Elseviet, 289–493.Google Scholar
Kittrick, J. A., 1982. Solubility of two high-Mg and two high-Fe chlorites using multiple equilibria. Clays & Clay Miner. 30: 167–169.Google Scholar
Kittrick, J. A., 1984. Solubility measurements of phases in three illites. Clays & Clay Miner. 32: 115–124.Google Scholar
Kübler, B., 1967. La cristallinité de I'illite et les zones tout a fait superieures du metamorphisme. In Étages Tectoniques. Colloque de Neuchatel 1966, 105–121.Google Scholar
Lee, J. H., Ahn, J. H., and Peacor, D. R. 1985. Textures in layered silicates: progressive changes through diagenesis and low-temperature metamorphism. J. Sed. Petrol. 55: 532–540.Google Scholar
Li, G., Mauk, J. L., and Peacor, D. R. 1995. Preservation of clay minerals in the Proterozoic (1.1 Ga) “Lower” Nonesuch Formation in the vicinity of the White Pine copper mine, Michigan. Clays & Clay Miner. 43: 361–376.Google Scholar
Liou, J. G., Maruyama, S., and Cho, M. 1987. Very low-grade metamorphism of volcanic and volcaniclastic rocks-Mineral assemblages and mineral facies. In Low Temperature Metamorphism. Frey, M., ed. Glasgow: Blackie, 59–113.Google Scholar
Lippmann, F., 1981. Stability diagrams involving clay minerals. In 8th Conf. Clay Miner. Petrol. Konata, J., ed. Praha, Czechoslovakia, Univ. Karlova: 153–171.Google Scholar
Lippmann, F., 1982. The thermodynamic status of clay minerals. In Proc. Int. Clay Conf. Bologna, Pavia, 1981, Olphen, H. van and Veniale, F., eds. NY: Elsevier, 475–485.Google Scholar
Loucks, R. R., 1992. The bound interlayer H2O content of potassic white micas: Muscovite-hydromuscovite-hydro-pyrophyllite solutions. Am. Miner. 76: 1563–1579.Google Scholar
Massonne, H.-J., and Schreyer, W. 1987. Phengite geoba-rometry based on the limiting assemblage with K-feldspar, phlogopite and quartz. Contr. Miner. Petrol. 96: 212–224.Google Scholar
Mattigod, S. V., and Sposito, G. 1978. Improved method for estimating the standard free energies of formation (ΔG) of smectites. Geochim. Cosmochim. Acta 50: 1667–1677.Google Scholar
May, H. M., Kinniburgh, D. G., Helmke, P. A., and Jackson, M. L. 1986. Aqueous dissolution, solubilities and thermodynamic stabilities of common aluminosilicate clay minerals: kaolinite and smectites. Geochim. Cosmochim. Acta 50: 1667–1677.Google Scholar
McOnie, A. W., Fawcett, J. J., and James, R. S. 1975. The stability of intermediate chlorites of the clinochlore-daphnite series at 2 kb PH2O. Am. Miner. 60: 1047–1060.Google Scholar
Merino, E., and Ransom, B. 1982. Free energies of formation of illite solid solutions and their compositional dependence. Clays & Clay Miner. 30: 29–39.Google Scholar
Merriman, R. J., Roberts, B., and Peacor, D. R. 1990. A transmission electron microscope study of white mica crystallite size distribution in a mudstone to slate transitional sequence, North Wales, UK. Contr. Miner. Petrol. 106: 27–40.Google Scholar
Morse, J. W., and Case, W. H. 1988. Ostwald processes and mineral paragenesis in sediments. Am. J. Sci. 288: 537–560.Google Scholar
Nadeau, P. H., and Reynold, R. C. Jr 1981. Burial and contact metamorphism in the Mancos Shale. Clays & Clay Miner. 29: 249–259.Google Scholar
Nieto, F., Velilla, N., Peacor, D. R., and Huertas, M. Ortega. 1994. Regional retrograde alteration of sub-greenschist facies chlorite to smectite. Contr. Miner. Petrol. 115: 243–252.CrossRefGoogle Scholar
Nriagu, J. O., 1975. Thermodynamical approximations for clay minerals. Am. Miner. 60: 834–839.Google Scholar
Ohr, M., Halliday, A. N., and Peacor, D. R. 1994. Mobility and fractionation of rare earth elements in argillaceous sediments: implications for dating diagenesis and low-grade metamorphism. Geochim. Cosmochim. Acta 58: 289–312.Google Scholar
Ostwald, W. Z., 1897. Studien über die Bildung und Umwandlung fester Körper. 1. Abhandlung: Berstattigung und Begrundlung. Zeit. Physik Chemie 22: 289–330.CrossRefGoogle Scholar
Peacor, D. R., 1992. Diagenesis and low-grade metamorphism of shales and slates. In Minerals and Reactions at the Atomic Scale: Transmission Electron Microscopy. Buseck, P. R., ed., Reviews in Mineralogy 27: 335–380.Google Scholar
Perry, E., and Hower, J. 1970. Burial diagenesis in Gulf Coast pelitic sediments. Clays & Clay Miner. 18: 167–177.Google Scholar
Pollastro, R. M., 1990. The illite/smectite geothermometer-concepts, methodology and application to basin history and hydrocarbon generation. In Applications of Thermal Maturity Studies to Energy Exploration. Nuccio, V. F., and Barker, C. E., eds. SEPM, 1–18.Google Scholar
Pollastro, R. M., 1993. Considerations of the illite-smectite geothermometer in hydrocarbon-bearing rocks of Miocene to Mississippian age. Clays & Clay Miner. 41: 119–133.Google Scholar
Pollastro, R. M., 1994. Clay diagenesis and mass balance—The forest and the trees. Clays & Clay Miner. 42: 93–97.Google Scholar
Powers, M. C., 1959. Adjustment of clays to chemical change and the concept of the equivalence level. Clays & Clay Miner. 6: 309–326.Google Scholar
Powers, M. C., 1967. Fluid-release mechanisms in compacting marine mudrocks and their importance in oil exploration. AAPG Bull. 51: 1240–1254.Google Scholar
Price, K. L., and McDowell, S. D. 1993. Illite/smectite geo-thermometry of the Proterozoic Oronto Group, Midcontinent Rift system. Clays & Clay Miner. 41: 134–147.Google Scholar
Pytte, A. M., and Reynolds, R. C. 1989. The thermal transformation of smectite to illite. In Thermal History of Sedimentary Basins. Naeser, N. D., and McCulloh, T. H., eds. Springer-Verlag, New York: 133–140.Google Scholar
Ransom, B., and Helgeson, H. C. 1993. Compositional end-members and thermodynamic components of illite and dioctahedral aluminous smectite solid solutions. Clays & Clay Miner. 41: 537–550.Google Scholar
Ransom, B., and Helgeson, H. C. 1994. A chemical and thermodynamic model of aluminous dioctahedral 2: 1 layer clay minerals in diagenetic processes: Regular solution representation of interlayer dehydration in smectite. Am. J. Sci. 294: 449–484.Google Scholar
Reynolds, R. C. Jr., and Hower, J. 1970. The nature of interlayering in mixed-layer illite-montmorillonite. Clays & Clay Miner. 18: 25–26.Google Scholar
Roberts, B., and Merriman, R. J. 1985. The distinction between Caledonian burial and regional metamorphism in metapelites from North Wales: an analysis of isocryst patterns. J. Geol. Soc. London 142: 615–624.Google Scholar
Robinson, D., and Bevins, R. E. 1986. Incipient metamorphism in the Lower Paleozoic marginal basin of Wales. J. Metam. Geol. 4: 101–113.Google Scholar
Sass, B. M., Rosenberg, P. E., and Kittrick, J. A. 1987. The stability of illite/smectite during diagenesis: an experimental study. Geochim. Cosmochim. Acta 51: 2103–2115.Google Scholar
Shau, Y.-H., Essene, E. J., and Peacor, D. R. 1990. Corrensite and mixed-layer chlorite/corrensite in metabasalt from northern Taiwan: TEM/AEM, EMPA, XRD, and optical studies. Contr. Miner. Petrol. 105: 123–142.CrossRefGoogle Scholar
Small, J. S., 1993. Experimental determination of the rates of precipitation of authigenic illite and kaolinite in the presence of aqueous oxalate and comparison to the K/Ar ages of authigenic illite in reservoir sandstones. Clays & Clay Miner. 41: 191–208.CrossRefGoogle Scholar
Sposito, G., 1986. The polymer model of thermodynamical clay mineral stability. Clays & Clay Miner. 34: 198–203.Google Scholar
Stoessell, R. K., 1979. A regular solution site-mixing model for illite. Geochim. Cosmochim. Acta 43: 1151–1159.Google Scholar
Stoessell, R. K., 1981. Refinements in a site-mixing model for illites: Local electrostatic balance and the quasi-chemical approximation. Geochim. Cosmochim. Acta 45: 1733–1741.Google Scholar
Suzuki, N., Matsubayashi, H., and Waples, D. W. 1993. A simpler kinetic model of vitrinite reflectance. AAPG Bull 77: 1502–1508.Google Scholar
Tardy, Y., and Duplay, J. 1992. A method of estimating the Gibbs free energies of formation of hydrated and dehydrated clay minerals. Geochim. Cosmochim. Acta 56: 3007–3029.Google Scholar
Tardy, Y., and Fritz, B. 1981. An ideal solid solution model for calculating solubility of clay minerals. Clay Miner. 16: 361–373.Google Scholar
Tardy, Y., and Garrels, R. M. 1974. A method for estimating the Gibbs energies of formation of layer silicates. Geochim. Cosmochim. Acta 45: 1733–1741.Google Scholar
Thornton, E. C. Jr., Seyfried, I. W. E., and Seewald, J. 1986. Chlorite solubility between 200° and 350°C: an experimental and theoretical modelling study. In Proceedings of the Workshop on Geochemical Modelling. Jackson, K. J., and Bourcier, W. L., eds. 184–188.Google Scholar
Turner, C. E., and Fishman, N. S. 1991. Jurassic Lake Toodichi: a large alkaline, saline lake, Morrison Formation, eastern Colorado Plateau. Geol. Soc. Amer. Bull. 103: 538–558.Google Scholar
van Santen, R. A., 1983. The Ostwald step rule. Jour. Phys. Chem. 88: 5768–5769.Google Scholar
Veblen, D. R., 1992. Electron microscopy applied to non-stoichiometry, polymetasomatism and replacement reactions in minerals. In Minerals and Reactions at the Atomic Scale: Transmission Electron Microscopy. Buseck, P. R., ed. Reviews in Mineralogy 27: 181–229.Google Scholar
Velde, B., 1965. Phengite micas: synthesis, stability and natural occurrences. Am. J. Sci. 263: 886–913.Google Scholar
Velde, B., 1969. The compositional join muscovite-pyrophyllite at moderate pressures and temperatures. Soc. Fr. Miner. Crystal. Bull. 92: 360–368.Google Scholar
Velde, B., 1985. Clay minerals: a Physico-chemical Explanation of their Occurrence: Devp. Sed. NY: Elsevier. 427 pp.Google Scholar
Velde, B., 1992a. Introduction to Clay Minerals. NY: Chapman and Hall, 198 pp.Google Scholar
Velde, B., 1992b. The stability of clays. In The Stability of Minerals. Price, G. D., and Ross, N. L., eds. London: Chapman and Hall, 329–351.Google Scholar
Velde, B., and Medhioub, M. 1988. Approach to chemical equilibrium in diagenetic chlorite. Contr. Miner. Petrol. 98: 122–127.Google Scholar
Velde, B., and Vasseur, G. 1992. Estimation of the diagenetic smectite/illite transformation in time-temperature space. Am. Miner. 77: 967–976.Google Scholar
Walshe, J. L., 1986. A six-component chlorite solid solution model and the conditions of chlorite formation in hydro-thermal and geothermal systems. Econ. Geol. 81: 681–703.Google Scholar
Walther, J. V., and Helgeson, H. C. 1977. Calculation of the thermodynamic properties of aqueous silica and the solubility of quartz and its polymorphs at high pressures and temperatures. Am. J. Sci. 277: 1315–1351.Google Scholar
Walther, J. V., and Wood, B. J. 1986. Fluid-Rock Interactions During Metamorphism. NY: Springer-Verlag, 218 pp.Google Scholar
Waples, D. W., 1980. Time and temperature in petroleum formation: application of Lopatin's method to petroleum exploration. AAPG Bull. 64: 916–926.Google Scholar
Whitney, G., 1990. Role of water in the smectite-to-illite reaction. Clays & Clay Miner. 38: 343–350.Google Scholar
Wintsch, R. P., O'Connoll, A. F., Ransom, B. L., and Wiechmann, M. J. 1981. Evidence for the influence of fCH4 on the crystallinity of disseminated carbon in greenschist facies rocks, Rhode Island, USA. Contr. Miner. Petrol. 77: 50–73.Google Scholar
Yau, Y.-C., Peacor, D. R., and McDowell, S. D. 1987. Smectite-to-illite reactions in Salton Sea shales: a transmission and analytical electron microscopy study. J. Sed. Petrol. 57: 345–342.Google Scholar
Yau, Y.-C., Peacor, D. R., Richard, E. B., Essene, E. J., and McDowell, S. D. 1988. Microstructures, formation mechanisms, and depth-zoning of phyllosilicates in geothermally altered shales, Salton Sea, California. Clays & Clay Miner. 36: 1–10.Google Scholar
Zen, E-An 1966. Construction of P-T diagrams for multi-component systems after the method of Schreinemakers—A geometrical approach. US Geol. Surv. Bull. 1225: 37 pp.Google Scholar