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Variability in temperature of the smectite/illite reaction in Gulf Coast sediments†

Published online by Cambridge University Press:  09 July 2018

R. L. Freed  and
D. R. Peacor
R. L. Freed
Affiliation:
Department of Geology, Trinity University, San Antonio, Texas 78284
D. R. Peacor
Affiliation:
Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA
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Abstract

Well-cuttings and core samples from four Gulf Coast areas have been examined by high-resolution scanning-transmission electron microscopy and other techniques to detail the chemical, mineralogical and textural changes during diagenesis. Wells in each of the four areas exhibit a distinct smectite-to-illite (S-I) transition, but the estimated depths for the transition vary significantly: 5600 to 8800 ft for the onset of the transition, and 7500 to 13 600 ft for the completion (70–80% illite). Calculated temperatures also vary significantly: 58° to 92°C for the onset, and 88° to 142°C for the completion. No pattern is evident for characteristic temperatures of the S-I transition. These data suggest that it is inappropriate to use the S-I transition for determining absolute diagenetic temperatures in geological settings similar to Gulf Coast sequences. TEM data imply the presence of two distinctly different kinds of domains, interpreted as smectite (with some mixed-layer component?) and illite. Initially, smectite domains dominate and contain subparallel layers of variable thickness. As the transition proceeds, abundant dislocations provide avenues for diffusion of both necessary reactants (K and Al) and products (Na, Si, Fe, Mg); illite packets grow within a shrinking matrix of smectite. Variable temperatures for the transition may be due to several factors, including chemical heterogeneity of the original smectite, variation in water/rock ratio, porosity differences, diverse chemical character of available fluids, and the particular physical environment for diagenesis. It is suggested that actual depths and temperatures for the transition are primarily a function of kinetic factors associated with a reaction for which at least one of the principal phases is metastable; the transition therefore is highly dependent on local geological factors.

Type
Research Article
Information
Clay Minerals , Volume 24 , Issue 2 , June 1989 , pp. 171 - 180
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1989

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Footnotes

†

Contribution number 457 from the Mineralogical Laboratory, Department of Geological Sciences, The University of Michigan, Ann Arbor, MI 48109, USA.

References

Ahn, J.H. & Peacor, D.R. (1985) Transmission electron microscope study of diagenetic chlorite in Gulf Coast argillaceous sediments. Clays Clay Miner. 33, 228–236.Google Scholar
Ahn, J.H. & Peacor, D.R. (1986) Transmission and analytical electron microscopy of the smectite-to-illite transition. Clays Clay Miner. 34, 165–179.Google Scholar
Bebout, D.G., Loucks, R.G., Bosch, S.C. & Dorfman, M.H. (1976) Geothermal resources—Frio Formation, upper Texas Gulf Coast. University of Texas at Austin, Bureau of Economic Geobgy Circuiar 76-3, 47 pp.Google Scholar
Bebout, D.G., Loucks, R.G. & Gregory, A.R. (1978) Frio sandstone reservoirs in the deep subsurface along the Texas Gulf Coast; their potential for production of geopressured geothermal energy. University of Texas at Austin, Bureau of Economic Geology Report of Investigations 91, 93 pp.Google Scholar
Bebout, D.G., Loucks, R.G. & Gregory, A.R. (1980) Geological aspects of Pleasant Bayou geopressured geothermal test well, Austin Bayou Prospect, Brazoria County, Texas. Pp. 11–45 in: Proc. Fourth U.S. Gulf Coast Geopressured-Geothermal Energy Conference, University of Texas at Austin.Google Scholar
Boles, J.R. (1982) Active albitization of plagioclase, Gulf Coast Tertiary. Am. J. Sci. 282, 165–180.CrossRefGoogle Scholar
Boles, J.R. & Franks, S.G. (1979) Clay diagenesis in Wilcox sandstones of southwest Texas: implications of smectite diagenesis on sandstone cementation. J. Sedim. 49, 55–70.Google Scholar
Burst, J.F. (1969) Diagenesis of Gulf Coast clayey sediments and its possible relation to petroleum migration. Bull. Am. Assoc. Petrol. Geol. 64, 73–93.Google Scholar
Freed, R.L. (1980) Shale mineralogy and burial diagenesis in four geopressured wells, Hidalgo and Brazoria Counties, Texas. Appendix A, pp. 111–172 in: Factors Controlling Reservoir Quality in Tertiary Sandstones and their Significance to Geopressured Geothermal Production (Loucks, R. G., Richmann, D. L. & Milliken, K. L.). Division of Geothermal Energy, U.S. Department of Energy, Contract No. DOE/ET/27111-1.Google Scholar
Freed, R.L. & Peacor, D.R. (1987) New insights on diagenesis and I/S reactions in Texas Gulf Coast pelitic sediments (abstract). Geol. Soc. Am. Abstr. Prog. 19, 667–668.Google Scholar
Guthrie, G.D. & Veblen, D.R. (in press) High resolution transmission electron microscopy of mixed-layer illite/smectite: I. Computer simulations. Clays Clay Miner. Google Scholar
Howard, J.J. (1987) Influence of shale fabric on illite/smectite diagenesis in the Oligocene Frio Formation, south Texas. Pp. 144–150 in: Proc. Int. Clay Conf., Denver 1985 ( Schultz, L. G., van Olphen, H. & F. A. Mumpton, , editors.) The Clay Minerals Society, Bloomington, Indiana.Google Scholar
Hower, J., Eslinger, E.V., Hower, M.E. & Perry, E.A. (1976) Mechanism of burial metamorphism of argillaceous sediments: 1. Mineralogical and chemical evidence. Bull. Geol. Soc. Am. 87, 725–737.2.0.CO;2>CrossRefGoogle Scholar
Lee, J.H., Peacor, D.R., Lewis, D.D. & Wintsch, R.P. (1984) Chlorite-illite/muscovite interlayered and interstratified crystals: a TEM/STEM study. Contr. Miner. Petrol. 88, 372–385.CrossRefGoogle Scholar
Lee, J.H., Ahn, J.H. & Peacor, D.R. (1985) Textures in layered silicates: progressive changes through diagenesis and low-temperature metamorphism. J. Sedim. Petrol. 55, 532–540.Google Scholar
Nadeau, P.H., Wilson, M.J., McHardy, W.J. & Tait, J.M. (1985) The conversion of smectite to illite during diagenesis: evidence from some illitic clays from bentonites and sandstones. Mineral Mag. 49,393-400.CrossRefGoogle Scholar
Perry, E. & Hower, J. (1970) Burial diagenesis in Gulf Coast pelitic sediments. Clays Clay Miner. 18,165-177.CrossRefGoogle 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. Bull. Am. Assoc. Petrol. Geol. 51, 1240–1254.Google Scholar
Reynolds, R.C. & Hower, J. (1970) The nature of interlayering in mixed-layer illite/montmorillonites. Clays Clay Miner. 18, 25–36.Google Scholar
Wallace, R.H., Kraemer, T.F., Taylor, R.E. & Wesselman, J.B. (1979) Assessment of geopressured- geothermal resources in the northern Gulf of Mexico basin. Pp. 132–155 in: Assessment of Geothermal Resources of the United States (Muffler, L. J. P., editor). US. Geol. Surv. Circ. 790.Google Scholar