Abstract
Area-weighted thickness distributions of fundamental illite particles for samples of illite and illite-smectite from seven locations (including bentonites and hydrothermally altered pyroclastics) were measured by Pt-shadowing technique, by transmission electron microscopy. Most thickness distributions are described by lognormal distributions, which suggest a unique crystallization process. The shapes of lognormal distributions of fundamental illite particles can be calculated from the distribution mean because the shape parameters α and β2are interrelated: β2= 0.107α − 0.03. This growth process was simulated by the mathematical Law of Proportionate Effect that generates lognormal distributions. Simulations indicated that illite particles grow from 2-nm thick illite nuclei by surface-controlled growth, i.e., the rate of growth is restricted by how rapid crystallization proceeds given a near infinite supply of reactants, and not by the rate of supply of reactants to the crystal surface. Initially formed, 2-nm thick crystals may nucleate and grow within smectite interlayers from material produced by dissolution of single smectite 2:1 layers, thereby transforming the clay from randomly interstratified (Reichweite, R = 0) to ordered (R = 1) illite-smectite after the smectite single layers dissolve. In this initial period of illite nucleation and growth, during which expandable layers range from 100 to 20%, illite crystals grow parallel to [001]* direction, and the dimensions of the (001) plane are confined to the size of the original smectite 2:1 layers. After nucleation ceases, illite crystals may continue to grow by surface-controlled growth, and the expandable-layer content ranges from 20 to 0%. This latter period of illitization is characterized by three-dimensional growth. Other crystal-growth mechanisms, such as Ostwald ripening, supply-controlled growth, and the coalescence of smectite layers, do not produce the observed evolution of α and β2and the observed shapes of crystal thickness distributions.
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Altaner, S.P and Ylagan, R.F. (1997) Comparison of structural models of mixed-layer illite/smectite and reaction mechanisms of smectite illitization. Clays and Clay Minerals, 45, 517–533.
Altaner, S.P., Weiss C.A., and Kirkpatrick R.J. (1988) Evidence from 29Si NMR for the structure of mixed-layer illite/smectite clay minerals. Nature, 331, 699–702.
Benjamin, J.R. and Cornell C.A. (1970) Probability and Decision for Civil Engineers. McGraw Hill Book Co., New York, 684 pp.
Clauer, N., Środoń, J., Francu, J., and Šucha, V. (1997) K-Ar dating of illite fundamental particles separated from illite-smectite. Clay Minerals, 32, 181–196.
Cuadros, J. and Altaner, S.P. (1998) Characterization of mixed-layer illite-smectite from bentonites using microscopic, chemical, and X-ray methods: Constraints on the smectite-to-illite transformation mechanism. American Mineralogist, 83, 762–774.
Drits, V.A., Środoń, J., and Eberl, D.D. (1997) XRD measurement of mean illite crystallite thickness: Reappraisal of the Kubler index and the Scherrer equation. Clays and Clay Minerals, 45, 461–475.
Drits, V.A., Eberl, D.D., and Środoń, J. (1998) XRD measurement of mean thickness, thickness distribution and strain for illite and illite/smectite crystallites by the Bertaut-Warren-Averbach technique. Clays and Clay Minerals, 46, 461–475.
Eberl, D.D. and Środoń, J. (1988) Ostwald ripening and interparticle diffraction effects for illite crystals. American Mineralogist, 73, 1335–1345.
Eberl, D.D., Środoń, J., Lee, M., Nadeau, P.H., and Northrop, H.R. (1987) Sericite from the Silverton caldera, Colorado: Correlation among structure, composition, origin, and particle thickness. American Mineralogist, 72, 914–935.
Eberl, D.D., Środoń, J., Kralik, M., Taylor, B., and Peterman, Z.E. (1990) Ostwald ripening of clays and metamorphic minerals. Science, 248, 474–477.
Eberl, D.D., Drits, V.A., and Środoń, J. (1998a) Deducing growth mechanisms for minerals from the shapes of crystal size distributions. American Journal of Science, 298, 499–533.
Eberl, D.D., Nüesch, R., Šucha, V., and Tsipursky, S. (1998b) Measurement of fundamental illite particle thickness by X-ray diffraction using PVP-10 intercalation. Clays and Clay Minerals, 46, 89–97.
Inoue, A. and Kitagawa, R. (1994) Morphological characteristics of illitic clay minerals from a hydrothermal system. American Mineralogist, 79, 700–711.
Inoue, A., Kohyama, N., Kitagawa, R., and Watanabe, T. (1987) Chemical and morphological evidence for the conversion of smectite to illite. Clays and Clay Minerals, 35, 111–120.
Inoue, A., Velde, B., Meunier, A., and Touchard, G. (1988) Mechanism of illite formation during smectite-to-illite conversion in a hydrothermal system. American Mineralogist, 73, 1325–1334.
Jennings, S. and Thompson, G.R. (1986) Diagenesis of Plio-Pleistocene sediments of the Colorado River delta, southern California. Journal of Sedimentary Petrology, 56, 89–98.
Jiang, W.-T, Peacor, D.R., Arkai, P., Toth, M., and Kim, J.W. (1997) TEM and XRD determination of crystallite size and lattice strain as a function of illite crystallinity in pelitic rocks. Journal of Metamorphic Geology, 15, 267–281.
Kapteyn, J.C. (1903) Skew Frequency Curves in Biology and Statistics. Astronomical Laboratory, Noordhoff, Groningen, 69 pp.
Lanson, B. and Champion, D. (1991) The I/S-to-illite reaction in the late stage diagenesis. American Journal of Science, 291, 473–506.
Nadeau, P.H. (1985) The physical dimensions of fundamental clay particles. Clay Minerals, 20, 499–514.
Nadeau, P.H. (1987) Relations between the mean area, volume and thickness for dispersed particles of kaolinites and micaceous clays and their application to surface area and ion exchange properties. Clay Minerals, 22, 351–356.
Nadeau, P.H., Wilson, M.J., McHardy, W.J., and Tait, J.M. (1984) Interstratified clays as fundamental particles. Science, 225, 923–935.
Reynolds, R.C., Jr. (1992) X-ray diffraction studies of illite/smectite from rocks, <1 μm randomly oriented powders, and <1 μm oriented powder aggregates: The absence of laboratory induced artifacts. Clays and Clay Minerals, 40, 387–396.
Reynolds, R.C., Jr. (1985) NEWMOD, a Computer Program for the Calculation of Basal X-Ray Diffraction Intensities of Mixed-Layered Clays. R.C. Reynolds, Hanover, NH. 03755.
Środoń, J., Morgan, D.J., Eslinger, E.V., Eberl, D.D., and Karlinger, M.R. (1986) Chemistry of illite/smectite and end-ember illite. Clays and Clay Minerals, 34, 368–378.
Środoń, J., Andreoli, C., Elsass, E., and Robert, M. (1990) Direct high-resolution transmission electron microscopic measurement of expandability of mixed-layer illite/smectite in bentonite rock. Clays and Clay Minerals, 38, 373–379.
Środoń, J., Elsass, F., McHardy, W.J., and Morgan, D.J. (1992) Chemistry of illite-smectite inferred from TEM measurements of fundamental particles. Clay Minerals, 27, 137–158.
Šucha, V., Kraus, I., Gerthofferova, H., Petes, J., and Serekova, M. (1993) Smectite to illite conversion in bentonites and shales of the East Slovak Basin. Clay Minerals, 28, 243–253.
Šucha, V., Środoń, J., Elsass, F., and McHardy, W.J. (1996) Particle shape versus coherent scattering domain of illite/smectite: Evidence from HRTEM of Dolna Ves clays. Clays and Clay Minerals, 44, 665–671.
Viczián, I. (1997) Hungarian investigations of the “Zempleni” illite. Clays and Clay Minerals, 45, 114–115.
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Środoń, J., Eberl, D.D. & Drits, V.A. Evolution of Fundamental-Particle Size during Illitization of Smectite and Implications for Reaction Mechanism. Clays Clay Miner. 48, 446–458 (2000). https://doi.org/10.1346/CCMN.2000.0480405
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DOI: https://doi.org/10.1346/CCMN.2000.0480405