Hostname: page-component-78c5997874-dh8gc Total loading time: 0 Render date: 2024-11-20T03:50:14.330Z Has data issue: false hasContentIssue false
  • English
  • Français

Zoned hibonites from Punalur, South India

Published online by Cambridge University Press:  05 July 2018

M. Santosh ,
M. Sandiford  and
S. J. B. Reed
M. Santosh
Affiliation:
Department of Geosciences, Faculty of Science, Osaka City University, Osaka 558, Japan Centre for Earth Science Studies, Akkulam, Trivandrum 695 031, India
M. Sandiford
Affiliation:
Department of Geology and Geophysics, University of Adelaide, Adelaide, G.P.O. Box 498, South Australia, Australia
S. J. B. Reed
Affiliation:
Department of Earth Sciences, Bullard Laboratories, Cambridge CB3 0EZ, U.K.
Get access Rights & Permissions [Opens in a new window]

Abstract

Zoned hibonites from a kalsilite, leucite, spinel, corundum, perovskite gneiss from the southern Indian granulite terrain near Punalur, Kerala, have rims that are the most Ti-rich yet recorded (0.83–0.87 Ti atoms per 19 O) and are essentially free of REE elements (ΣREE < 0.01 atoms per 19 O) while the cores are the most REE-rich compositions yet recorded (ΣREE = 0.55–0.65 atoms per 19 O). Within the limits of analytical uncertainty, the compositions of the hibonite can be related to the theoretical end-member CaAl12O19 by the substitutions REE R2+ ⇌ CaAl and R2+R4+ ⇌ Al2 with the REE-rich cores containing in excess of 50% of the REE R2+ Al11O19 end member. Minor substitution of Na for Ca occurs in the rims, while non-stoichiometry in both the cores and rims is indicated by partial 12-fold site occupancy. Ion-microprobe analysis of the REE-rich hibonites reveals strong enrichment in LREE with La/Lu c. 250 000.

Keywords

hiboniterare earth elementstitaniumzoningion-microprobe analysisIndia
Type
Mineralogy and Geochemistry
Information
Mineralogical Magazine , Volume 55 , Issue 379 , June 1991 , pp. 159 - 162
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1991

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

Burns, R. G. and Burns, V. M. (1984) Crystal chemistry of meteoritic hibonites, Proc 15th Lunar Planet. Set. Conf., J. Geophys. Res. supplement, 89, C313–21.CrossRefGoogle Scholar
Curien, H., Guillemin, C., Orcel, J., and Steinberg, M. (1956) La hibonite, nouvelle espece minerale. C.R. Acad. Sci. Paris, 242, 2845–7.Google Scholar
Kuzmin, A. M. (1960) Hogbomite from Gornaya Shoriya. Geol. Geof. 4, 63–75.Google Scholar
Maaskant, P., Coolen, J. J. M. M. M., and Burke, E. A. J. (1980) Hibonite and coexisting zoisite in a calcsilicate granulite from southern Tanzania. Min. Mag. 43, 995–1003.CrossRefGoogle Scholar
Reed, S. J. B. (1986) Ion microprobe determination of rare earth elements in accessory minerals. Mineral. Mag. 50, 3–15.CrossRefGoogle Scholar
Sandiford, M. and Santosh, M. (1990) A granulite facies kalsilite-leucite-hibonite association from Punalur, southern India. Min. Petrol, (in press).CrossRefGoogle Scholar
Yakovlevskaya, T. A. (1961) Hibonite from Gornaya Shoriya. Zap. Vses. Min. Obshch. 90, 458-61.Google Scholar