TY - JOUR

T1 - Experimental study of fluorine and chlorine contents in mica (biotite) and their partitioning between mica, phonolite melt, and fluid

AU - Chevychelov, V. Yu

AU - Botcharnikov, Roman

AU - Holtz, Francois

N1 - Funding Information: This study was supported by the German Academic Exchange Service (DAAD grant nos. 325, 2004), the Russian Foundation for Basic Research (project no. 05-0.5-64754) and Program for the Support of Leading Scientific Schools (NSh-3763.2008.5). The authors are grateful to O.G. Safonov for the discussion of the manuscript and helpful comments. Copyright: Copyright 2009 Elsevier B.V., All rights reserved.

PY - 2008/12/3

Y1 - 2008/12/3

N2 - This paper reports the results of a study of the composition of mica (biotite) crystallizing in the system of phonolite melt-Cl- and F-bearing aqueous fluid at T ∼ 850°C, P = 200 MPa, and fO2 = Ni-NiO, as well as data on F and Cl partitioning between coexisting phases. It was established that Cl content in mica is significantly lower than in phonolite melt and, especially, in fluid. Fluorine shows a different behavior in this system: its content in mica is always higher than in phonolite melt but lower than in fluid. The mica-melt partition coefficients of Cl and F also behave differently. The Cl partition coefficient gradually increases from 0.17 to 0.33 with increasing Cl content in the system, whereas the partition coefficient of F sharply decreases from 3.0 to 1.0 with increasing total F content. The apparent partition coefficients of F between biotite and groundmass (melt) in various magmatic rocks are usually significantly higher than the experimental values. It was supposed that the higher Bt/glassDF values in natural samples could be related to the influence of later oxidation reactions, reequilibration of biotite at continuously decreasing fH2O/ fHF ratio, and an increase in this coefficients with decreasing total F content in the system.

AB - This paper reports the results of a study of the composition of mica (biotite) crystallizing in the system of phonolite melt-Cl- and F-bearing aqueous fluid at T ∼ 850°C, P = 200 MPa, and fO2 = Ni-NiO, as well as data on F and Cl partitioning between coexisting phases. It was established that Cl content in mica is significantly lower than in phonolite melt and, especially, in fluid. Fluorine shows a different behavior in this system: its content in mica is always higher than in phonolite melt but lower than in fluid. The mica-melt partition coefficients of Cl and F also behave differently. The Cl partition coefficient gradually increases from 0.17 to 0.33 with increasing Cl content in the system, whereas the partition coefficient of F sharply decreases from 3.0 to 1.0 with increasing total F content. The apparent partition coefficients of F between biotite and groundmass (melt) in various magmatic rocks are usually significantly higher than the experimental values. It was supposed that the higher Bt/glassDF values in natural samples could be related to the influence of later oxidation reactions, reequilibration of biotite at continuously decreasing fH2O/ fHF ratio, and an increase in this coefficients with decreasing total F content in the system.

UR - http://www.scopus.com/inward/record.url?scp=54449087744&partnerID=8YFLogxK

U2 - 10.1134/S0016702908110025

DO - 10.1134/S0016702908110025

M3 - Article

AN - SCOPUS:54449087744

VL - 46

SP - 1081

EP - 1089

JO - Geochemistry International

JF - Geochemistry International

SN - 0016-7029

IS - 11

ER -