Barium phlogopite from the Jacupiranga carbonatite, Brazil

Creators: Gaspar, Jose C.; Wyllie, Peter J.

Abstract

Phlogopites from the carbonatites intruded into the Jacupiranga alkalic complex have FeO/(FeO + MgO) within the restricted range 0.06 to 0.12, and BaO varying from 0.1 up to 10.3 wt.%. Zoning with respect to BaO may be small, or it may exceed 3-4% BaO. Phlogopites and biotites from other carbonatites contain much less BaO, commonly below 0.7%, but values of FeO/(FeO+ MgO) range up to 0.66. Phlogopites from mantle peridotite nodules and kimberlites have BaO contents less than 0.7%, with FeO/(FeO + MgO) varying from low values for mantle phlogopites (corresponding to those of the Jacupiranga carbonatites) up to values of at least 0.7 for kimberlite phlogopites. Leucite-bearing lavas contain high Ba micas with FeO/(FeO + MeO) from 0.09-0.6, and BaO up to 7.3%.

Additional Information

© 1982 Mineralogical Society of America. Manuscript received, January 26, 1982; accepted for publication, June 8, 1982. We thank Serrana S/A de Mineração, G. C. Melcher, and V. A. V. Girardi for making possible the field work of JCG, I. M. Steele for invaluable assistance with microprobe analyses, and J. V. Smith for information about analyzed micas. Financial support was provided by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) PROC 201.158/80 and PROC 40.1410/81, Fundação de Amparo à Pesquisa do Estado de Sao Paulo (FAPESP) PROC 80/470 and PROC 81/0168-8, and the Earth Science Division of the National Science Foundation Grants EAR 76-20410, and EAR 81-08599.

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Barium phlogopite from the Jacupiranga carbonatite, Brazil

Abstract

Additional Information

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