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Transmission and Analytical Electron Microscopy Evidence for High Mg Contents of 1M Illite: Absence of 1M Polytypism in Normal Prograde Diagenetic Sequences of Pelitic Rocks

Published online by Cambridge University Press:  01 January 2024

Donald R. Peacor ,
Blanca Bauluz ,
Hailiang Dong ,
David Tillick  and
Yonghong Yan
Donald R. Peacor*
Affiliation:
Department of Geological Sciences, The University of Michigan, Ann Arbor, Michigan, 48109-1063, USA
Blanca Bauluz
Affiliation:
Departamento de Ciencias de la Tierra, Cristalografía y Mineralogía, Universidad de Zaragoza, 50.009 Zaragoza, Spain
Hailiang Dong
Affiliation:
Department of Geology, Miami University, Oxford, OH 45056, USA
David Tillick
Affiliation:
Daveyhurst, c/- Croesus Mining NL, 39 Porter St., Kalgoorlie, WA 6430, Australia
Yonghong Yan
Affiliation:
25 Harris Street, #23, Acton, MA, 01720, USA
*
*E-mail address of corresponding author: drpeacor@umich.edu
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Abstract

The normal prograde diagenetic and low-grade metamorphic sequence of dioctahedral clay minerals including illite-rich I-S and illite, as observed by TEM, proceeds from a partially disordered 1Md stacking sequence to 2M1; i.e. 1M does not normally occur as an intermediate polytype. Examples of 1M illite stacking sequences have been studied, however, from the Golden Cross gold deposit, New Zealand, the Broadlands-Ohaaki geothermal system, New Zealand, the Potsdam Sandstone, New York, and the Silverton Caldera, Colorado. Specific clay-mineral packets identified by TEM techniques as 1M illite were found to have anomalously high Mg contents. The Broadlands illite provides the most definitive data, as separate packets of 1M and 2M1 illite coexist. Average compositions for 1M and 2M1 illite are (K1.66Ca0.04)Σ1.70(Al3.32Fe0.31Mg0.57Mn0.06)Σ4.26(Si6.43Al1.57)Σ8O20(OH)4 and (K1.57Na0.31Ca0.03)Σ1.91(Al3.58Fe0.05Mg0.29Mn0.01)Σ3.93(Si6.70Al1.30)Σ8O20(OH)4, respectively. In addition, 1Mdillite, which is the polytype occurring in the common 1Mdto 2M1 prograde sequence, is relatively Mg poor, but coexists with Mg-rich illite in the Silverton Caldera sample.

These data confirm that 1M stacking is caused by compositional anomalies, and thus explain the lack of the 1M stacking sequence in normal diagenetic sequences in pelitic rocks, as most illite in such environments has a relatively small phengitic component. The parameter Δz, a measure of the corrugation of the oxygen sheets, may be the key parameter reflecting the polytypic state of dioctahedral and trioctahedral micaceous minerals. Such composition-determined relations may be related to the occurrence of 1M polytypism in glauconite and celadonite, both dioctahedral 2:1 clay minerals having large Mg or Fe octahedral-cation components, and in trioctahedral micas. Insofar as the 1M stacking sequence does not have the same composition as 2M1 material, these data confirm that the different varieties of illite are not polytypes, sensu stricto.

Keywords

IllitePolytypismTransmission Electron Microscopy

Information

Type
Research Article
Information
Clays and Clay Minerals , Volume 50 , Issue 6 , December 2002 , pp. 757 - 765
Copyright
Copyright © 2002, The Clay Minerals Society

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References

Abbott, R.N. and Burnham, C.W., (1988) Polytypism in micas: A polyhedral approach to energy calculations American Mineralogist 73 105 118.Google Scholar
Bailey, S. W. (1984a) Classification and structures of micas. Pp. 1–13 in: Micas (Bailey, S.W., editor). Reviews in Mineralogy, 13. Mineralogical Society of America, Chelsea, Michigan.CrossRefGoogle Scholar
Bailey, S.W. and Bailey, S.W., (1984) Crystal chemistry of the true micas Micas Chelsea, Michigan Mineralogical Society of America 10.1515/9781501508820 Pp. 13–60.CrossRefGoogle Scholar
Bailey, S.W., (1988) X-ray diffraction identification of the polytypes of mica, serpentine and chlorite Clays and Clay Minerals 36 193–213 10.1346/CCMN.1988.0360301.CrossRefGoogle Scholar
Bauluz, B. Peacor, D.R. and Gonzalez Lopez, J.M., (2000) TEM study of illitization in pelites from the Iberian Range, Spain: Layer-by-layer replacement? Clays and Clay Minerals 48 374–384 10.1346/CCMN.2000.0480308.CrossRefGoogle Scholar
Brigatti, M.F. Frigieri, P. and Poppi, L., (1998) Crystal chemistry of Mg-, and Fe-bearing muscovites-2M 1 American Mineralogist 83 775–785 10.2138/am-1998-7-809.CrossRefGoogle Scholar
Caillère, S. Henin, S. and Rautureau, M., (1982) Mineralogie des Argiles. II. Classification et Nomenclature Paris Masson 45 87.Google Scholar
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 2M 1 polytypism Clays and Clay Minerals 44 257–275 10.1346/CCMN.1996.0440211.CrossRefGoogle Scholar
Drits, V.A. Plançon, A. Sakharov, B.A. Besson, G. Tsipursky, S.I. and Tchoubar, C., (1984) Diffraction effects calculated for structural models of K-saturated montmorillonite containing different types of defects Clay Minerals 19 541–562 10.1180/claymin.1984.019.4.03.Google Scholar
Drits, V.A. Dainyak, L.G. Muller, F. Besson, G. and Manceau, A., (1997) Isomorphous cation distribution in celadonites, glauconites and Fe-illites determined by infrared, Mössbauer and EXAFS spectroscopies Clay Minerals 32 153–179 10.1180/claymin.1997.032.2.01.CrossRefGoogle Scholar
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 72 914 934.Google Scholar
Grathoff, G.H. and Moore, D.M., (1996) Illite polytype quantification using WILDFIRE© calculated X-ray diffraction patterns Clays and Clay Minerals 44 835–842 10.1346/CCMN.1996.0440615.CrossRefGoogle Scholar
Grubb, S.M.B. Peacor, D.R. and Jiang, W.-T., (1991) Transmission electron microscope observations of illite polytypism Clays and Clay Minerals 39 540–550 10.1346/CCMN.1991.0390509.CrossRefGoogle Scholar
Lee, J.H. and Guggenheim, S., (1981) Single crystal X-ray refinement of pyrophyllite-1 Tc. American Mineralogist 66 350 367.Google Scholar
Lonker, S.W. and Fitzgerald, J.D., (1990) Formation of coexisting 1M and 2M polytypes in illite from an active hydrothermal system American Mineralogist 75 1282 1289.Google Scholar
Maxwell, D.T. and Hower, J., (1967) High-grade diagenesis and low-grade metamorphism of illite in the precambrian belts series American Mineralogist 52 843 857.Google Scholar
Meunier, A. and Velde, B., (1989) Solid solutions in I/S mixed-layer minerals and illite American Mineralogist 74 1106 1112.Google Scholar
Reynolds, R.C. Jr., (1994) WILDFIRE©: A computer program for the calculation of three-dimensional X-ray diffraction patterns for mica polytypes and their disordered variations 8 Brook Road, Hanover, New Hampshire R.C. Reynolds, Jr..Google Scholar
Reynolds, R.C. Jr. and Thomson, C.H., (1993) Illite from the Potsdam Sandstone of New York: A probable noncentrosymmetric mica structure Clays and Clay Minerals 41 66–72 10.1346/CCMN.1993.0410107.CrossRefGoogle Scholar
Tillick, D.A. Peacor, D.R. and Mauk, J.L., (2001) Genesis of dioctahedral phyllosilicates during hydrothermal alteration of volcanic rocks: I. The Golden Cross epithermal ore deposit, New Zealand Clays and Clay Minerals 49 126–140 10.1346/CCMN.2001.0490203.CrossRefGoogle Scholar
Velde, B., (1965) Experimental determination of muscovite polymorph stabilities American Mineralogist 50 436 449.Google Scholar
Velde, B., (1965) Phengitic micas: Synthesis, stability, and natural occurrence American Journal of Science 263 886–913 10.2475/ajs.263.10.886.CrossRefGoogle Scholar
Yan, Y. Tillick, D.A. Peacor, D.R. and Simmons, S.F., (2001) Genesis of dioctahedral phyllosilicates during hydrothermal alteration of volcanic rocks: The Broadlands hydrothermal system, New Zealand Clays and Clay Minerals 49 141–155 10.1346/CCMN.2001.0490204.CrossRefGoogle Scholar
Yoder, H.S. and Eugster, H.P., (1955) Synthetic and natural muscovites Geochimica et Cosmochimica Acta 8 225–280 10.1016/0016-7037(55)90001-6.CrossRefGoogle Scholar
Zoller, M. and Brockamp, O., (1997) 1M- and 2M1-illites: different minerals and not polytypes European Journal of Mineralogy 9 821–827 10.1127/ejm/9/4/0821.CrossRefGoogle Scholar