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Mineralogical and Morphological Evidence for the Formation of Illite at the Expense of Illite/Smectite

Published online by Cambridge University Press:  02 April 2024

Richard M. Pollastro
Richard M. Pollastro*
Affiliation:
U.S. Geological Survey, Federal Center, Denver, Colorado 80225
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Abstract

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The conversion of smectite to illite by way of a mixed-layer illite/smectite (I/S) series was found to be the major depth-related reaction in clay-mineral assemblages from two cored sedimentary sequences in the Rocky Mountains. The I/S reaction occurred in both interbedded sandstone and shale of Upper Cretaceous and lower Tertiary age in the Green River basin, Wyoming, and in chalk and chalky shale of the Upper Cretaceous Niobrara Formation, Denver basin, Colorado. As the proportion of illite layers in I/S increased with depth in these rocks, the amount of I/S in the clay fraction decreased, and the amount of discrete illite increased. Scanning electron microscopy revealed that the morphologies of highly expansible, randomly interstratified I/S clay (samples from shallow cores) exhibited no distinctive intergrowth or overgrowth textures. In deeply buried rocks containing highly illitic, ordered I/S and abundant discrete illite, however, fibers or laths of illite were formed on earlier I/S substrates. Less commonly, I/S of low expandability shows morphological features of both smectite and illite whereby rigid laths of illite appear to have formed diagenetically from the wall surfaces of I/S honeycombs. This combined morphology suggests some dissolution and reprecipitation (or some reorganization) of materials from the I/S substrate as the substrate was transformed into a more illitic mixed-layer clay.

These data suggest that some I/S clay was destroyed by the selective cannibalization of smectite layers in I/S to provide the components needed to make a more illitic I/S. Moreover, discrete illite and other minerals apparently were formed during the reaction. Also, coarser mineral phases, such as potassium feldspar and detrital micas, may not have been required to supply the chemical components in the reaction. The observations provide an explanation for late diagenetic I/S reactions that occurred in restricted or relatively closed geochemical systems, as in early cemented rocks having extremely low permeability and little or no potassium feldspar.

Keywords

DiagenesisIlliteIllite/smectiteMorphologyScanning electron microscopyX-ray powder diffraction
Type
Research Article
Information
Clays and Clay Minerals , Volume 33 , Issue 4 , August 1985 , pp. 265 - 274
Copyright
Copyright © 1985, The Clay Minerals Society

References

Almon, W. R. and Davies, D. K., 1977 Understanding diagenetic zones vital Oil and Gas J. 75 209–216.Google Scholar
Altaner, S., Aronson, J. L., Whitney, C. G. and Hower, J., 1984 Model for K-bentonite formation: evidence from zoned K-bentonite in the disturbed belt, Montana Geology 12 412–415.2.0.CO;2>CrossRefGoogle Scholar
Boles, J. R. and Franks, S. G., 1979 Clay diagenesis in Wilcox sandstones of southwest Texas: implications of smectite diagenesis on sandstone cementation J, Sediment. Petrol. 49 55–70.Google Scholar
Carson, B. and Arcaro, N. P., 1983 Control of clay-mineral stratigraphy by selective transport in Late Pleistocene-Holocene sediments of northern Cascadia basin–Juan de Fuca Abyssal Plain: implications for studies of clay-mineral provenance J. Sediment. Petrol. 53 395–406.Google Scholar
Drever, J.I., 1973 The preparation of oriented clay mineral specimens for X-ray diffraction analysis by a filter membrane peel technique Amer. Mineral. 58 553–554.Google Scholar
Foscolos, A. E. and Powell, T. G., 1980 Mineralogical and geochemical transformation of clays during catagenesis and their relation to oil generation Facts and Principles of World Petroleum Occurrence, A. D. Miall, ed., Canadian Soc. Pet. Geol. Memoir 6 153–172.Google Scholar
Hayes, J. B., 1979 Sandstone diagenesis—the hole truth Aspects of Diagenesis, P. A. Scholle and P. R. Schluger, eds., Soc. Econ. Paleontol. Mineral. Spec. Publ. 26 127–139.Google Scholar
Hoffman, J., 1976 Regional metamorphism and K-Ar dating of clay minerals in Cretaceous sediments of the disturbed belt of Montana Ph.D. Thesis Cleveland, Ohio Case Western Reserve University.Google Scholar
Hower, J., 1981 Shale diagenesis Short Course in Clays and the Resource Geologist, F. J. Longstaffe, ed., Mineral. Assoc. Canada Short Course Handbook 7 60–80.Google Scholar
Hower, J., Eslinger, E., Hower, M. and Perry, E., 1976 The mechanism of burial diagenetic reactions in argillaceous sediments, 1. Mineralogical and chemical evidence Geol. Soc. Amer. Bull. 87 725–737.2.0.CO;2>CrossRefGoogle Scholar
Law, B. E., Pollastro, R. M., Keighin, C.W., Spencer, C. W. and Mast, R. F., 1985 Geologic characterization of low-permeability gas reservoirs in selected wells, greater Green River basin, Wyoming, Colorado, and Utah Geology of Tight Reservoirs (in press).CrossRefGoogle Scholar
McHargue, T. R. and Price, R. C., 1982 Dolomite from clay in argillaceous or shale-associated marine carbonates J. Sediment. Petrol. 51 553–562.Google Scholar
Pollastro, R. M. (1982) A recommended procedure for the preparation of oriented clay-mineral specimens for X-ray diffraction analysis: modifications to Drever’s filtermembrane-peel technique: U.S. Geol. Surv. Open File Rept. 82–71, 10 pp.Google Scholar
Pollastro, R. M. and Bader, J. W., 1983 Clay-mineral relationships in some low-permeability hydrocarbon reservoirs and their use as predictive resource tools Amer. Assoc. Petrol. Geol. Bull. 67 536 (abstract).Google Scholar
Pollastro, R. M. and Barker, C. E., 1984 Geothermometry from clay minerals, vitrinite reflectance, and fluid inclusions—applications to the thermal and burial history of rocks cored from the Wagon Wheel No. 1 well, Green River basin, Wyoming Geological Characteristics of Low-permeability Upper Cretaceous and Lower Tertiary Rocks in the Pindale Anticline Area, Sublette County, Wyoming, B. E. Law, ed., U.S. Geol. Surv. Open-File Rept. 84–753 78–94.Google Scholar
Pollastro, R. M. and Scholle, P. A., 1985 Diagenetic relationships in a hydrocarbon-productive chalk: the Cretaceous Niobrara Formation U.S. Geol. Surv. Bull (in press).Google Scholar
Reynolds, R. C. Jr., Brindley, G. W. and Brown, G., 1980 Interstratified clay minerals Crystal Structures of Clay Minerals and Their X-ray Identification London Mineralogical Society 249–303.CrossRefGoogle Scholar
Reynolds, R. C. Jr. and Hower, J., 1970 The nature of interlayering in mixed-layer illite-montmorillonites Clays & Clay Minerals 18 25–36.CrossRefGoogle Scholar
Schultz, L. G. (1964) Quantitative interpretation of mineralogical composition from X-ray and chemical data for the Pierre Shale: U.S. Geol. Surv. Prof. Pap. 391–C, 31 pp.Google Scholar
Schultz, L. G. (1978) Mixed-layer clay in the Pierre Shale and equivalent rocks, northern Great Plains region: U.S. Geol. Surv. Prof. Pap. 1064–A, 28 pp.Google Scholar
Sommer, F., 1978 Diagenesis of Jurassic sandstone in the Viking graben J. Geol. Soc. 135 63–67.CrossRefGoogle Scholar
Towe, K. M., 1974 Quantitative clay petrology: the trees but not the forest? Clays & Clay Minerals 22 375–378.CrossRefGoogle Scholar
Weaver, C. E. (1979) Geothermal alteration of clay minerals and shales: diagenesis: Office of Nuclear Waste Isolation Tech. Rept. 21, 176 pp.Google Scholar
Wilson, M. D., 1982 Origins of clays controlling permeability in tight gas sands J. Petrol. Tech. 34 2871–2876.CrossRefGoogle Scholar
Wilson, M. D. and Pittman, E. D., 1977 Authigenic clays in sandstones: recognition and influence on reservoir properties and paleoenvironmental analysis J. Sediment. Petrol. 47 3–31.Google Scholar