Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-26T09:24:55.107Z Has data issue: false hasContentIssue false
  • English
  • Français

Mafic phyllosilicates in low-grade metabasites. Characterization using deconvolution analysis — discussion

Published online by Cambridge University Press:  09 July 2018

S. Hillier
S. Hillier*
Affiliation:
Macaulay Land Use Research Institute, CraigiebucklerAberdeen, AB9 2Q J, UK
Get access Rights & Permissions [Opens in a new window]

Abstract

Any X-ray diffraction (XRD) pattern of mixed-layered maximum R1 ordered chlorite-smectite has an exact equivalent R0 smectite-corrensite or R0 chlorite-corrensite. The identification of a mineral as chlorite (0.8)-smectite R1 is, therefore, not evidence that the fundamental layers in such an interstratified structure are actually chlorite and smectite. Furthermore, there are no obvious differences between XRD patterns of R0 and R1 chlorite-smectite at high or low smectite contents. Therefore the frequently supposed identification of R0 chlorite-smectite with high smectite contents is also questionable. It follows that the identification of R1 chlorite (0.8)-smectite by Robinson & Bevins (1994) and of R0 chlorite (≈0.2)-smectite in an earlier publication (Robinson et al.,1993) cannot be used as evidence regarding the debate over the nature of the component layers in interstratified minerals intermediate between trioctahedral smectite and chlorite.

Diffraction patterns of natural mixed-layer chlorite minerals from metabasites often show a strong reflection at 31 Å yet a lack of resolution of other mixed-layer peaks from those of discrete chlorite. These features cannot be matched by any single mixed-layer mineral consisting of layers of chlorite and smectite and were matched by Robinson & Bevins (1994) using a mixture of different chlorite-smectite minerals. However, they can be matched by a single chlorite-corrensite mineral in which there is an element of segregation of layer types. These different possibilities need to be investigated further.

Type
Research Article
Information
Clay Minerals , Volume 30 , Issue 1 , March 1995 , pp. 67 - 73
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1995

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Drits, V.A. & Tchoubar, C. (1990) X-ray Diffraction by Disordered Lamellar Structures. Springer Verlag, Berlin.Google Scholar
Hillier, S. (1993) Origin, diagenesis, and mineralogy of chlorite minerals in Devonian Lacustrine mudrocks, Orcadian Basin, Scotland. Clays Clay Miner. 41, 240–259.CrossRefGoogle Scholar
Reynolds, R.C. JR. (1980) Interstratified clay minerals. Pp. 249–304 in: Crystal Structures of Clay Minerals and their X-ray Identification (Brindley, G. W. & Brown, G., editors). Mineralogical Society, London.Google Scholar
Reynolds, R.C. JR. (1985) NEWMOD A Computer Program for the Calculation of the One-Dimensional Patterns of Mixed-Layered Clays. Reynolds, R. C., 8 Brook Rd. Hanover, New Hampshire.Google Scholar
Reynolds, R.C. JR. (1988) Mixed-layer chlorite minerals. Pp. 601—629 in: Hydrous Phyllosilicates (Exclusive of Micas) (Bailey, S. W., editor). Reviews in Mineralogy 19. Mineralogical Society of America, Washington, DC.Google Scholar
Robinson, D. & Bevins, R.E. (1994) Mafic phyllosilicates in low-grade metabasites. Characterization using deconvolution analysis. Clay Miner. 29, 223—237.CrossRefGoogle Scholar
Robinson, D., Bevlns, R.E. & Rowbotham, G. (1993) The characterization of mafic phyllosilicates in low-grade metabasites from eastern North Greenland. Am. Miner. 78, 377–390.Google Scholar
Sato, M. (1965) Structure of interstratified (mixed-layer) minerals. Nature, 208, 70–71,Google Scholar
Shau, Y.H. & Peacor, D.R. (1992) Phyllosilicates in hydrothermally altered basalts from DSDP Hole 504B, Leg 83 - a TEM and AEM study. Contrib. Miner. Pet. 112, 119–133.CrossRefGoogle Scholar
Shau, Y.H., Peacor, D.R. & Essene, E.J. (1990) Corrensite and mixed-layer chlorite/corrensite in metabasalt from northern Taiwan: TEM/AEM, EMPA, XRD, and optical studies. Contrib. Miner. Pet. 105, 123–142.Google Scholar