Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-26T22:35:30.639Z Has data issue: false hasContentIssue false
  • English
  • Français

Application of a thermodynamic model to predict the mineral stability of titaniferous smectites from soils on volcanic rocks

Published online by Cambridge University Press:  09 July 2018

J. L. Martin de Vidales ,
J. Casas  and
J. Sanz
J. L. Martin de Vidales
Affiliation:
Departamento de Geología y Geoquímica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco28049-Madrid
J. Casas
Affiliation:
Instituto de Edafologia y Biologia Vegetal, Consejo Superior de Investigaciones Científicas, Serrano, 115, 28006-Madrid, España
J. Sanz
Affiliation:
Departamento de Geología y Geoquímica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco28049-Madrid
Get access Rights & Permissions [Opens in a new window]

Abstract

Weathering processes in the Piedrabuena volcano, Ciudad Real province, Central Spain, have produced a smectitic phyllosilicate in four profiles on porphyritic-holocrystalline basalts consisting mainly of titaniferous augites, olivine and pigeonite. Chemical analysis of the purified smectites gave TiO2 contents of 1·89–3·77%. Apart from one profile, the smectites showed high tetrahedral Al-for-Si substitution, with the lattice charge arising from this source exceeding that from octahedral substitution, and thus could be termed beidellites. Octahedral Ti contents ranged from 0·21 to 0·41 per 24 O. A thermodynamic model was used to estimate the ΔG° of formation of these titaniferous smectites. Values ranged between −2503·30 and −2543·26 Kcal/mol. Suitable equilibria were established by calculating their ΔG° of reaction and log Ksp and, from these, the stability diagrams pH - 1/2pMg2+ against log H4SiO4 were derived. Correlations found were: (i) strong and positive between AlVI-X+ (0·91), AlIV-FeVI (0·85), AlVI-FeVI (0·85) and AlVI-MgVI (0·76); (ii) strong and negative between AlIV-octahedral charge; (iii) solubility product (log Ksp) positively correlated with X+ (0·73), AlIV (0·89), FeVI (0·67) and MgVI (0·84). Smectites showing higher tetrahedral charges were the least stable. Conversely, the stabilities of titaniferous smectites were favoured by high values of pH - 1/2pMg2+ and/or activities in soil-matrix solution. When the activities of H4SiO4 decreased, the montmorillonitic smectites became less stable than those showing beidellitic characteristics. Variations in composition and stability of the titaniferous smectites were not correlated with soil depth.

Type
Research Article
Information
Clay Minerals , Volume 21 , Issue 3 , September 1986 , pp. 389 - 400
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1986

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Carson, C.D., Krrrrick, J.A., Dixon, J.A. & McKee, T.R. (1976) Stability of soil smectites from a Houston black clay. Clays Clay Miner. 24, 151–155.CrossRefGoogle Scholar
Garrels, R.M. & Christ, C.L. (1965) Solutions, Minerals and Equilibrium. Harper and Row, London. 450 pp.Google Scholar
Kittrick, J.A. (1971a) Soil solution composition and stability of clay minerals. Soil Sci. Soc. Am. Proc. 35, 451–453.CrossRefGoogle Scholar
Kittrick, J.A. (1971b) Stability of montmorillonites: I. Belle Fourche and Clay Spur montmorillonites. Soil Sci. Soc. Am. Proc. 35, 140–145.CrossRefGoogle Scholar
Kittrick, J.A. (1971c) Montmorillonite equilibria and the weathering environment. Soil Sci. Soc. Am. Proc. 35, 815–820.CrossRefGoogle Scholar
Kittrick, J.A. (1971d) Stability of montmorillonites: II. Aberdeen montmorillonite. Soil Sci Soc. Am. Proc. 35, 820–823.CrossRefGoogle Scholar
Lindsay, W. (1979) Chemical Equilibria in Soils, pp. 150–160. John Wiley and Sons, New York.Google Scholar
Marshall, C.E. (1959) The Colloid Chemistry of the Silicate Minerals. Academic Press Inc., New York.Google Scholar
Martin De Vidales, J.L., Sanz, J., Guijarro, J., Hoyos, M.A. & Casas, J. (1985) Smectite origins in the volcanic soils of the Calatrava Region (Central Spain). Proc. 5th Meeting European Clay Groups, Prague, 465–470.Google Scholar
Misra, U.K. & Upchurch, W.J. (1976) Free energy of formation of beidellite from apparent solubility measurements. Clays Clay Miner. 24, 327–331.CrossRefGoogle Scholar
Robie, R.A. & Waldbaum, D.R. (1968) Thermodynamic properties of mineral and related substances at 298.15 K (25°C) and one atmosphere (1.013 bars pressure and at higher temperatures. U.S. Geol. Surv. Bull. 1259.Google Scholar
Sanz, J., Martin De Vidales, J.L., Casas, J. & Guerra, A. (1982) Procesos de alteración, génesis y estabilidad mineral de suelos volcánicos. Anal. Edaf. y Agrob. XLI, 801–814.Google Scholar
Singer, A. (1985) The clay mineralogy of basalt-derived paleosols. Proc. 5th Meeting European Clay Groups, Prague, 453–458.Google Scholar
Tardy, Y. & Garrels, R.M. (1974) A method of estimating the Gibbs energies of formation of layer silicates. Geochim. Cosmochim. Acta 88, 1101–1116.CrossRefGoogle Scholar
Tardy, Y. & Fritz, B. (1981) An ideal solid solution model for calculating solubility of clay minerals. Clay Miner. 16, 361–373.CrossRefGoogle Scholar
Tardy, Y. (1982) Kaolinite and smectite stability in weathering conditions. Estudios Geol6gicos 38, 295–312.Google Scholar
Weaver, R.M., Jackson, M.L. & Syers, J.K. (1971) Magnesium and silicon activities in matrix solutions of montmorillonite-containing soils in relation to clay mineral stability. Soil Sci. Soc. Am. Proc. 35, 823–830.CrossRefGoogle Scholar
Weaver, R.M., Jackson, M.L. & Syers, J.K. (1976) Clay minerals as related to activities of aluminium, silicon and magnesium in matrix solution of montmorillonite containing soils. Clays Clay Miner. 24, 246–252.CrossRefGoogle Scholar
Weir, A.H. & Green-Kelly, R. (1962) Beidellite. Am. Miner. 47, 137–146.Google Scholar