Abstract
Siltstones from the Precambrian Freda Formation in Wisconsin have been studied by scanning, scanning-transmission and analytical electron microscopy (SEM, STEM and AEM), and X-ray diffraction (XRD). XRD data for drill core samples show a change from smectite-rich Illite-Smectite (I-S) in shallow samples to illite in deeper samples, implying a transition during burial diagenesis.
Transmission electron microscopy (TEM) observations of shallow samples reveal the presence of three clearly distinguishable kinds of dioctahedral clay minerals: (1) detrital grains of micrometer-sized, mature muscovite; (2) small packets in the matrix consisting of dominant (Reichweite) R1 I-S or (3) small packets of illite. The illite and I-S stacks occur separately and have similar textures, with packet thicknesses averaging ∼400 Å, within the range of anchizonal illite. Illite and detrital muscovite commonly display strain features typical of the effects of tectonic stress. Void space within I-S or illite packets is inferred to be a strain feature, and to have served as pathways for fluids. Detrital muscovite shows abundant alteration features including (001) boundaries which are continuous with parallel packets of I-S; individual layers commonly show along-layer transitions of muscovite to smectite or I-S. Trioctahedral clays consist primarily of detrital chlorite which commonly shows direct alteration to R1 I-S and smectite, as with detrital muscovite.
Deep samples contain only unaltered, coarse detrital muscovite, and thin packets of illite forming stacks and comprising most of the matrix. The texture of the illite appears to be identical to that of shallow samples, with characteristics such as packet size typical of anchizonal illite. Trioctahedral clays consist almost entirely of detrital grains of chlorite and corrensite. They occur as separate grains with rather constant composition, without signs of alteration.
The data imply that all of the studied rocks have been subjected to a uniform anchizonal grade of metamorphism in which detrital grains were largely unchanged but matrix clays were transformed to packets of illite. The unusually abrupt transition with depth from highly expandable I-S to illite is inferred to actually be the result of subsequent alteration of authigenic illite and detrital chlorite and muscovite to R1 I-S and smectite in shallow rocks. This late overprinting of the anchimetamorphic clay mineral assemblage is inferred to have been locally caused by fluids with temperatures less than those of peak metamorphism. This process, called “retrograde diagenesis”, gave rise to a sequence of dioctahedral I-S and illite which mimics classic prograde sequences. Interpretations of such sequences as being prograde, especially in cases of ancient rocks, should be interpreted with caution when high-resolution images of textures are not available.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Ahn, J.H. and Peacor, D.R. (1985) Transmission electron microscopic study of diagenetic chlorite in Gulf Coast argillaceous sediments. Clays and Clay Minerals, 33, 228–236.
Arkai, P., Merriman, R.J., Roberts, B., Peacor, D.R., and Tom, M. (1996) Crystallinity, crystallite size and lattice strain of illite-muscovite and chlorite: Comparison of XRD and TEM data for diagenetic to epizonal pelites. European Journal of Mineralogy, 8, 1119–1137.
Cannon, W.E., Green, A.G., Hutchinson, D.R., Lee, M., Milkereit, B., Behrendt, J.C., Halls, H.C., Green, J.C., Dickas, A.B., Morey, G.B., Sutcliffe, R., and Spencer, C. (1989) The North American Midcontinent rift beneath Lake Superior from GLIMPCE seismic reflection profiling. Tectonics, 8, 305–332.
Cannon, W.E., Peterman, Z.E., and Sims, P.K. (1990) Structural and isotopic evidence for middle Proterozoic thrust faulting of Archean and early Proterozoic rocks near the Gogebic range, Michigan and Wisconsin. Institute on Lake Superior Geology Proceedings, 36, 11–113.
Davis, D.W. and Sutcliffe, R.H. (1985) U-Pb ages from the Nipigon Plate and Northern Lake Superior. Geological Society of America Bulletin, 96, 1572–1579.
Davis, D.W. and Paces, J.B. (1990) Time resolution of geologic events on the Keweenaw Peninsula and implications for development of the Midcontinent Rift system. Earth and Planetary Science Letters, 97, 54–64.
Dong, H. and Peacor, D.R. (1996) TEM observations of coherent stacking relations in smectite, I/S and illite of shales: Evidence for MacEwan crystallites and dominance of 2M1 polytypism. Clays and Clay Minerals, 44, 257–275.
Evans, M.A. and Battles, D.A. (1997) Regional syn-orogenic fluid migration in the central Appalachians: Fluid geochemistry and fluid migration pathways. In Contributions to the Second International Conference on Fluid Evolution, Migration and Interaction in Sedimentary Basins and Orogenic Belts, Belfast, Northern Ireland, J.P. Hendry, F.E. Carey, J. Parnell, A.H. Ruffell, and R.H. Worden, eds., 85–88.
Gordon, M.B. and Hempton, M.R. (1986) Collision induced rifting: The Grenville orogeny and Keweenawan rift of North America. Tectonophysics, 127, 1–25.
Guthrie, G.D., Jr. and Veblen, D.R. (1989) High-resolution transmission electron microscopy of mixed-layer illite/smectite: Computer simulations. Clays and Clay Minerals, 37, 1–11.
Guthrie, G.D., Jr. and Veblen, D.R. (1990) Interpreting one-dimensional high-resolution transmission electron micrographs of sheet silicates by computer simulation. American Mineralogist, 75, 276–288.
Hedgman, C.A. (1992) Provenance and tectonic setting of the Jacobsville Sandstone, from Ironwood to Keweenaw Bay, Michigan. M.S. thesis, University of Cincinnati, Cincinnati, Ohio, 158 pp.
Hower, J., Eslinger, E.V., Hower, M.E., and Perry, E.A. (1976) Mechanism of burial metamorphism of argillaceous sediments: Mineralogical and chemical evidence. Geological Society of America Bulletin, 87, 725–737.
Hutchinson, D.E., White, R.S., Cannon, W.E., and Schultz, K.J. (1990) Keweenawan hot spot: Geophysical evidence for a 1.1 Ga mantle plume beneath the Midcontinent rift system. Journal of Geophysical Research, 95, 10869–10884.
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 and Clay Minerals, 38, 449–468.
Jiang, W.T., Peacor, D.R., and Essene, E.J. (1994) Clay minerals in the MacAdams sandstone, California: Implications for substitution of H3O+ and H2O and metastability of illite. Clays and Clay Minerals, 42, 35–45.
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.
Kim, J.W., Peacor, D.R., Tessier, D., and Elsass, F. (1995) A technique for maintaining texture and permanent expansion of smectite interlayers for TEM observations. Clays and Clay Minerals, 43, 51–57.
Li, G., Mauk, J.L., and Peacor, D.R. (1995) Preservation of clay minerals in the Precambrian (1.1 Ga) Nonesuch Formation in the vicinity of the White Pine Copper Mine, Michigan. Clays and Clay Minerals, 43, 361–376.
Merriman, R.J., Roberts, B., Peacor, D.R., and Hirons, S.R. (1995) Strain-related differences in the crystal growth of white mica and chlorite: a TEM and XRD study of the development of metapelitic microfabrics in the Southern Uplands thrust terrane, Scotland. Journal of Metamorphic Geology, 13, 559–576.
Nicholson, S.W. and Shirey, S.B. (1990) Midcontinent rift volcanism in the Lake Superior region: Sr, Nd, and Pb isotopic evidence for a mantle plume origin. Journal of Geophysical Research, 95, 10851–10868.
Nieto, E., Velilla, N., Peacor, D.R., and Huertas, M.O. (1994) Regional retrograde alteration of sub-greenschist faces chlorite to smectite. Contributions to Mineralogy and Petrology, 115, 243–252.
Palmer, H.C. and Davis, D.W. (1987) Paleomagnetism and U-Pb geochronology of Michipicoten Island: Precise calibration of the Keweenawan polar wander track. Precambrian Research, 37, 158–171.
Price, K.L. and McDowell, S.D. (1993) Illite/smectite geo-thermometry of the Proterozoic Oronto group, Midcontinent rift system. Clays and Clay Minerals, 41, 134–147.
Price, K.L., Huntoon, J.E., and McDowell, S.D. (1996) Thermal history of the 1.1-Ga Nonesuch Formation, North American mid-continent rift. White Pine, Michigan. American Association of Petroleum Geologists Bulletin, 80, 1–15.
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 and Clay Minerals, 38, 1–13.
Ziegler, K. and Longstaffe, F.J. (1997) Hydrogen isotopes from clay minerals and fluid flow along Precambrian/Cambrian unconformity in SW Ontario, Canada. In Contributions to the Second International Conference on Fluid Evolution, Migration and Interaction in Sedimentary Basins and Orogenic Belts. Belfasts, Northern Ireland, J.P., Hendry, P.F. Carey, J. Parnell, A.H. Ruffell, and R.H. Worden, eds., 343–346.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Zhao, G., Peacor, D.R. & Douglas Mcdowell, S. “Retrograde Diagenesis” of Clay Minerals in the Precambrian Freda Sandstone, Wisconsin. Clays Clay Miner. 47, 119–130 (1999). https://doi.org/10.1346/CCMN.1999.0470202
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1346/CCMN.1999.0470202