Karel Vybíhal, Jiří Faimon


Perthitic feldspar weathered in batch reactor (weight ratio feldspar/water ~ 4/15) during long-term (300 day) laboratory experiments at ambient conditions. During first 50 days of the experiment, aqueous concentrations of Si, Al, K, Na, and Ca reached limiting values 3.4x10-4, 9.2x10-5, 1.5x10-4, 1.2x10-4, 1.1x10-4 mol/l, respectively. Despite the fact, the studied system was still far away from equilibrium. High supersaturation with respect to secondary minerals (gibbsite, pyrophyllite, Ca-beidellite, K-beidellite, Na-beidellite, and kaolinite) and to primary minerals (albite and K-feldspar) was reached in the solution. Reaction paths on predominant stability diagrams crossed the stability field of gibbsite and kaolinite, and points to the Na-beidelite and K-feldspar stability fields. Based on X-ray diffraction, only muscovite and illite were proved. Electron microprobe analyses showed decreasing Al/Si stoichiometry of secondary phases during time.

Bibliografická citace

Vybíhal, K., & Faimon, J. (2016). EXPERIMENTÁLNÍ ZVĚTRÁVÁNÍ PERTHITICKÉHO ŽIVCE. Geologické výzkumy na Moravě a ve Slezsku, 11. Získáno z https://journals.muni.cz/gvms/article/view/4938

Klíčová slova

experiment; modeling; perthitic feldspar; saturation; secondary phase; weathering

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Appelo, C. A. J. – Postma, D. (1994): Geochemistry, groundwater and pollution. – A. A. Balkema, Rotterdam, Brookfield.

Faimon, J. (1995): Vznik kolidů při zětrávání silikátů. – PhD thesis, Masaryk University, Brno.

Faimon, J. (1998): Kinetics of the release of silicon and aluminium from aluminosilicates into aqueous mildly acid solutions. – Scripta Fac. Sci. Nat. Univ. Masaryk Brun., 1995, 59–68. Brno (Czech Rep.), Masaryk University.

Helgeson, H. C. – Garrels, R. M. – MacKenzie, F. T. (1969): Evaluation of irreversible reactions in geochemical processes involving minerals and aqueous solutions – II. Applications. – Geochim. Cosmochim. Acta, 33, 455–481.

Helgeson, H. C. – Murphy, W. M. – Aagaard, P. (1984): Thermodynamic and kinetic constraints on reaction rates among minerals and aqueous solutions. II. Rate constants, effective surface area, and the hydrolysis of feldspar. – Geochim. Cosmochim. Acta, 48, 2405–2432.

Hess, P. C. (1966) Phase equilibrium of some minerals in the K2O-Na2O-Al2O3-SiO2-H2O system at 25oC and 1 atmosphere. – Am. J. Sci., 264, 289–309.

Islam, M. R. – Start, R. – Risto, A. – Vesa, P. (2002): Mineralogical changes during intense chemical weathering of the sedimentary rocks in Bangladesh. – J. Asian Earth Sci., 20, 889–901.

Oliveira, M. T .G. De – Formoso, M. L. L. – Trescases, J. J. – Meunier, A. (1998): Clay mineral facies and lateritization in basalts of the southeastern Parana Basin, Brazil. – J. South. Am. Earth Sci., 11, 365–377.

Parham, W. E. (1969): Halloysite-rich tropical weathering products of Hong Kong. – Clay. Conf. 1969, I., 403–416.

Parkhurst, D. L. – Appelo, C. A. J. (1999): User‘s guide to phreeqc (version-2) – a computer program for speciation, batchreaction, one-dimensional transport, and inverse geochemical calculations. – http: //www.xs4all.nl/~appt/index.htm.

Tonui, E. – Eggleton, T. – Taylor, G. (2003): Micromorphology and chemical weathering of a K-rich trachyandezite and an associated sedimentary cover (Parkes, SE Australia). – Catena, 53, 181–207.