Hostname: page-component-586b7cd67f-rdxmf Total loading time: 0 Render date: 2024-11-28T14:21:29.957Z Has data issue: false hasContentIssue false
  • English
  • Français

Chemical variation in garnets from aplites and pegmatites, peninsular Thailand

Published online by Cambridge University Press:  05 July 2018

D. A. C. Manning
D. A. C. Manning*
Affiliation:
Centre de Recherches Pétrographiques et Géochimiques, B.P.20, 54501 Vandoeuvre-lès-Nancy, France
Get access Rights & Permissions [Opens in a new window]

Abstract

Electron microprobe analyses of almandine-spessartine garnets from pegmatites and aplites from the Hub Kapong batholith and Phuket Island in peninsular Thailand show three types of zoning. Garnets from pegmatites show extreme zoning, with Mn-rich cores (⋍ 80 % spessartine) and Mn-poor rims (⩾ 40 % spessartine), whereas those from aplites are either unzoned (35–40% spessartine) within the limits of detection, or have Mn-enriched rims (cores 45 %, rims 55 % spessartine). The origin of the three types of zoning is considered to reflect different crystal growth histories in each case. The pegmatitic garnets grew under conditions favourable for the development and preservation of marked concentration gradients—low nucleation density, rapid growth rate and slow cation diffusion rates for the crystal and rapid diffusion rates for the pegmatitic liquid. The aplitic garnets had a more complex growth history, with slower growth rates and faster diffusion rates for the crystal, coupled with slower diffusion rates within the aplite magma, tending to prevent the formation and preservation of concentration gradients. Subsequent resorption of aplitic garnets at lower temperatures gave rise to Mn-rich rims because of the preferential retention of Mn by the garnet; lower cation diffusion rates within the crystal permitted these marginal concentration gradients to be preserved.

Type
Research Article
Information
Mineralogical Magazine , Volume 47 , Issue 344 , September 1983 , pp. 353 - 358
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1984

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.)

Footnotes

*

Present address: Dept. of Geology, The University, Newcastle upon Tyne, NEI 7RU.

References

Atherton, M. P. (1968) Contrib. Mineral. Petrol. 18, 347–71.CrossRefGoogle Scholar
Bizouard, H., Capdevila, R., and Gaven, C. (1970) Bol. Geol. Min. lnst. Geol. Min. Espana. 81, 185–90.Google Scholar
Cerny, P. (1982) In Granite pegmatites in science and industry (Cerny, P., ed.). MAC short course handbook, 8, 405–61.Google Scholar
Clemens, J. D., and Wall, V. J. (1981) Can. Mineral. 19, 111–31.Google Scholar
Dunham, A. C and Wilkinson, F. G. F. (1978) X-ray Spectrom. 2. 50-6.Google Scholar
Freer, R. (1981) Contrib. Mineral. Petrol. 76, 440–54.CrossRefGoogle Scholar
Garson, M. S., Young, B., Mitchell, A. H. G., and Tait, B. A. R. (1975) The geology of the tin belt in peninsular Thailand around Phuket, Phangnga and Takua Pa. Overseas Mem. lnst. Geol. Sci. London, 1.Google Scholar
Grant, J. A., and Weiblen, P. W. (1971) Am. J. Sci. 270, 281–96.CrossRefGoogle Scholar
Green, T. H. (1977) Contrib. Mineral. Petrol. 65, 59–67.CrossRefGoogle Scholar
Hall, A. (1965) Mineral. Mag. 35, 628–33.Google Scholar
Jahns, R. H., and Burnham, C. W. (1969) Econ. Geol. 64, 843–64.CrossRefGoogle Scholar
Kistler, R. W., Ghent, E. D., and O'Neil, J. R. (1981) J. Geophys. Res. 86, 10591–606.CrossRefGoogle Scholar
Manning, D. A. C. (1982) Mineral. Mag. 45, 139–47.CrossRefGoogle Scholar
Miller, C. F., and Stoddard, E. F. (1981) J. Geol. 89, 233–46.CrossRefGoogle Scholar
Paraskevopoulos, G., Ottemann, J., and Agiorgitis, G. (1972) Tschermak's Mineral. Petrogr. Mitt. 17, 247–9.CrossRefGoogle Scholar
Weisbrod, A. (1974) Bull. Soc. Fr. Mineral. Cristallogr. 97, 261–70.Google Scholar
Yardley, B. W. D. (1977) Am. Mineral. 62, 793–800.Google Scholar