Hostname: page-component-cc8bf7c57-fxdwj Total loading time: 0 Render date: 2024-12-11T22:56:36.440Z Has data issue: false hasContentIssue false
  • English
  • Français

Smectite Illitization in Pliocene-Age Gulf of Mexico Mudrocks

Published online by Cambridge University Press:  28 February 2024

J. H. Rask ,
L. T. Bryndzia ,
N. R. Braunsdorf  and
T. E. Murray
J. H. Rask
Affiliation:
Shell Western E&P Company, 200 N. Dairy Ashford, Houston, Texas 77079
L. T. Bryndzia
Affiliation:
U.S. EPA/NRMRL, 5995 Center Hill Drive, Cincinnati, Ohio 45224
N. R. Braunsdorf
Affiliation:
Shell E&P Technology Company, Bellaire Technology Center, PO Box 481, Houston, Texas 77001
T. E. Murray
Affiliation:
Shell Development Company, Westhollow Technology Center, PO Box 1382, Houston, Texas 77001
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Utilizing high-resolution transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS) and X-raydiffraction (XRD) techniques, we have studied the transition from shallower smectite-rich mudrocks to deeper illite-rich mudrocks in Pliocene-age turbidite sediments from the northern Gulf of Mexico (GOM). Our objective in this work was to better understand how the smectite-illite transition may affect the onset of geopressuring in GOM sediments. The samples studied were sidewall cores from an offshore Louisiana well. In previous studies of GOM sediments, the smectite-to-illite reaction has mainly been documented in considerably older, Miocene-age sediments.

The results of this study elucidate the reaction mechanisms entailed in the transformation of clays in this sediment from smectitic to illitic. We found that illite formed at the expense of smectite in 2 ways: 1) growth of preexisting discrete illite flakes, and 2) creation of new illite layers within mixed-layer illite-smectite. Also, illitization apparently proceeded via a dissolution/precipitation, Al-conserving reaction rather than a solid-state, layer-conserving reaction. Smectite illitization is commonly believed to require input of K from feldspar dissolution. Our XRD results found little correlation between decreases in K-feldsparand increases of illite. However, in 1 instance TEM/EDS analyses indicated the presence of high-charge smectite, which suggests that insufficient K was available for illitization. TEM images also show small packets of authigenic chlorite in illite-rich mudrock. This chlorite may act as a sink for Fe liberated upon smectite illitization.

Keywords

Clay DiagenesisCore AnalysisGulf of MexicoIlliteSmectiteTEMXRD
Type
Research Article
Information
Clays and Clay Minerals , Volume 45 , Issue 1 , February 1997 , pp. 99 - 109
Copyright
Copyright © 1997, The Clay Minerals Society

References

Ahn, J.H. and Buseck, P.R.. 1990. Layer-stacking sequences and structural disorder in mixed-layer illite/smectite: Image simulation and TEM imaging. Am Mineral 75: 267–275.Google Scholar
Ahn, J.H. and Peacor, D.R.. 1985. Transmission electron microscopic study of diagenetic chlorite in Gulf Coast argillaceous sediments. Clays Clay Miner 33: 228–236.CrossRefGoogle Scholar
Ahn, J.H. and Peacor, D.R.. 1986. Transmission and analytical electron microscopy of the smectite to illite transition. Clays Clay Miner 34: 165–179.Google Scholar
Bell, T.E.. 1986. Microstructure in mixed-layer illite/smectite and its relationship to the reaction of smectite to illite. Clays Clay Miner 34: 146–154.CrossRefGoogle Scholar
Bethke, C.M. and Altaner, S.P.. 1986. Layer-by-layer mechanism of smectite illitization and application to a new rate law. Clays Clay Miner 34: 136–145.CrossRefGoogle Scholar
Boles, J.R. and Franks, S.G.. 1979. Clay diagenesis in the Wilcox sandstones of Southwest Texas: Implications of smectite diagenesis on sandstone cementation. J Sed Petrol 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 53: 73–93.Google Scholar
Eberl, D.. 1993. Three zones for illite formation during burial diagenesis and metamorphism. Clays Clay Miner 41: 26–37.CrossRefGoogle Scholar
Freed, R.L. and Peacor, D.R.. 1989a. Variability in the temperature of the smectite/illite reaction in Gulf Coast sediments. Clay Miner 24: 171–180.CrossRefGoogle Scholar
Freed, R.L. and Peacor, D.R.. 1989b. Geopressured shale and sealing effect of smectite to illite transition. AAPG Bull 73: 1223–1232.Google Scholar
Guthrie, G.D. Jr and Veblen, D.R.. 1989. High-resolution transmission electron microscopy of mixed-layer illite/smectite: Computer simulations. Clays Clay Miner 37: 1–11.CrossRefGoogle Scholar
Howard, J.J.. 1991. Porosimetry measurement of shale fabric and its relationship to illite/smectite diagenesis. Clays Clay Miner 39: 355–361.CrossRefGoogle Scholar
Hower, J.. 1981. Shale diagenesis. In: Longstaffe, F.T., editor. Clays and the resource geologist. Short course handbook 7. Ottawa: Mineral Assoc Canada. p 60–80.Google Scholar
Hower, J., Eslinger, E.V., Hower, M. and Perry, E.A.. 1976. Mechanism of burial metamorphism of argillaceous sediment: 1. Mineralogical and chemical evidence. GSA Bull 87: 725–737.2.0.CO;2>CrossRefGoogle Scholar
Jiang, W.T., Peacor, D.R., Merriman, R.J. and Roberts, B.. 1990. Transmission and analytical electron microscopic study of mixed-layer illite/smectite formed as an apparent replacement product of diagenetic illite. Clays Clay Miner 38: 449–468.CrossRefGoogle Scholar
Klimentides, R.E. and MacKinnon, I.D.R.. 1986. High-resolution imaging of ordered mixed-layer clays. Clays Clay Miner 34: 155–164.CrossRefGoogle Scholar
MacKinnon, I.D.R.. 1990. Low-temperature analyses in the analytical electron microscope. In: MacKinnon, I.D.R., Mumpton, F.A., editors. CMS workshop lectures, vol. 2: Electronoptical methods in clay science. Boulder, CO: Clay Miner Soc. p 90–106.Google Scholar
Moore, D.M. and Reynolds, R.C.. 1989. X-ray diffraction and the identification and analysis of clay minerals. NY: Oxford Univ Pr. 384 p.Google Scholar
Pearson, M.J., Watkins, D. and Small, J.S.. 1982. Clay diagenesis and organic maturation in Northern North Sea sediments. Proc Int Clay Conf; Italy. p 665–675.Google Scholar
Perry, E. and Hower, J.. 1970. Burial diagenesis in Gulf Coast pelitic sediments. Clays Clay Miner 18: 165–177.CrossRefGoogle Scholar
Shaw, H.F. and Primmer, T.J.. 1989. Diagenesis in shales from a partly overpressured sequence in the Gulf Coast, Texas, USA. Marine Petrol Geol 6: 121–128.CrossRefGoogle Scholar
Spinnler, G.E., Self, P.G., Iijima, S. and Buseck, P.R.. 1984. Stacking disorder in clinochlore chlorite. Am Mineral 69: 252–263.Google Scholar
Surdam, R.C. and Crossey, L.J.. 1987. Integrated diagenetic modeling: A process-oriented approach for clastic systems. Annu Rev Earth Planet Sci 15: 141–170.CrossRefGoogle Scholar
Vali, H. and Koster, H.M.. 1986. Expanding behavior, structural disorder, regular and random irregular interstratification of 2: 1 layer silicates studied by high-resolution images of transmission electron microscopy. Clay Miner 21: 827–859.CrossRefGoogle Scholar
Veblen, D.R.. 1983. Microstructures and mixed layering in intergrown wonesite, chlorite, talc, biotite, and kaolinite. Am Mineral 68: 566–580.Google Scholar
Veblen, D.R., Guthrie, G.D. Jr, Livi, K.J.T. and Reynolds, R.C. Jr. 1990. High-resolution transmission electron microscopy and electron diffraction of mixed-layer illite/smectite: Experimental results. Clays Clay Miner 38: 1–13.CrossRefGoogle Scholar
Velde, B. and Vasseur, G.. 1992. Estimation of the diagenetic smectite to illite transformation in time-temperature space. Am Mineral 77: 967–976.Google Scholar