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Empirical calibration of the sulphur valence oxygen barometer from natural and experimental glasses: method and applications

Published online by Cambridge University Press:  05 July 2018

S. J. Matthews ,
D. H. S. Moncrieff  and
M. R. Carroll
S. J. Matthews
Affiliation:
Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, BS8 1RJ, UK
D. H. S. Moncrieff
Affiliation:
Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, BS8 1RJ, UK
M. R. Carroll
Affiliation:
Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, BS8 1RJ, UK
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Abstract

New data on sulphur valence and magmatic oxidation state for Central Andean volcanic rocks, in combination with published data for experimental and natural samples, allow derivation of a simple relationship between magma oxidation state and sulphur speciation. For a number of highly oxidized Central Andean volcanic rocks fO2 has been calculated using magnetite-ilmenite or olivine-spinel pairs and the sulphur valence in glasses has been measured using the peak shift of S-Kα radiation relative to a pyrite standard. Previously published experimental and natural data have been incorporated with a wider range in fO2 and S valence. The variation in sulphur speciation (as S2- or SO42-) as a function of log fO2 is described by an empirical polynomial fit which reproduces the data to within ±0.5 log units and allows use of electron microprobe measurements of the S-Kα wavelength shift for estimation of magmatic oxygen fugacities. This approach is applicable for fO2 between FMQ-2 and FMQ+6, encompassing most terrestrial magmas. The method has been used to calculate the in fO2 conditions under which melt inclusions were trapped in andesitic magmas before magma mixing in two Central Andean volcanoes, and to calculate the oxygen fugacity of a slowly-cooled pyroclastic flow in which the Fe-Ti oxide phases have subsequently re-equilibrated. In combination with Fe-Ti oxide data, two distinct trends emerge for Lascar volcano. Basaltic andesite-andesitic magma chambers follow T-fO2 trends which parallel the FMQ buffer curve, indicating ferrous-ferric iron buffering of oxygen fugacity. Dacitic anhydrite-bearing magmas with admixed basaltic andesite and andesite follow trends of increasing fO2 with decreasing temperature, indicative of buffering of fO2 by SO2-H2S in a co-magmatic gas phase. This trend continues into the metamorphic aureole of the magma chamber, resulting in highly oxidized (close to magnetite-hematite) conditions.

Keywords

sulphur valencesilicate meltsoxygen fugacity
Type
Research Article
Information
Mineralogical Magazine , Volume 63 , Issue 3 , June 1999 , pp. 421 - 431
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1999

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Footnotes

*

Present address: Servicio Nacional de Geologia y Mineria, Avenida Santa Maria 0104, Casilla 10465, Santiago, Chile.

References

Bacon, C.D. and Hirschmann, M.M. (1988) Mg/Mn partitioning as a test for equilibrium between coexisting Fe-Ti oxides. Amer. Mineral., 73, 57–61.Google Scholar
Ballhaus, C., Berry, R.F. and Green, D.H. (1990) Oxygen fugacity controls in the earths upper mantle. Nature, 348, 437–40.CrossRefGoogle Scholar
Carroll, M.R. and Rutherford, M.J. (1987) The stability of igneous anhydrite: experimental results and implications for sulfur behaviour in the 1982 El Chichon trachyandesite and other evolved magmas. J. Petrol., 28, 781–801.CrossRefGoogle Scholar
Carroll, M.R. and Rutherford, M.J. (1988) Sulfur speciation in hydrous experimental glasses of varying oxidation state: Results from measured wavelength shifts of sulfur X-rays. Amer. Mineral., 73, 845–9.Google Scholar
Faesler, A. and Goehring, M. (1952) Rontenspectrum und Bindungszustand die kα Fluorescenstralung des Schwefels. Naturwissenschaften, 39, 169–77.Google Scholar
Frost, B.R. and Lindsley, D.H. (1992) Equilibria among Fe-Ti oxides, pyroxenes, olivine, and quartz: Part II. Application. Amer. Mineral., 77, 1004–20.Google Scholar
Gardeweg, M. (1988) Petrografia y geochimica del complejo volcanico Tumisa, Altiplano de Antofagasta, Andes del Norte de Chile. Congreso Geologico Chileno, 5. Servicio Nacional de Geologia y Mineria, Chile, pp. 183–208.Google Scholar
Gardeweg, M.C. (1991) The geology, petrology and geochemistry of the Tumisa Volcanic Complex, North Chile. Unpub. PhD. Thesis, Kingston Polytechnic. 374 pp.Google Scholar
Gardeweg, M.C., Fuentealba, G., Murillo, M. and Petit-Breulh, M.E. (1994) Volcan Lascar: Geologia y Evaluacion del Riesgo Volcanico-Altiplano II Region. Informe Registrado, 1994-3, Biblioteca Servicio Nacional de Geologia y Mineria, Chile. 169 pp.Google Scholar
Gardeweg, M.C., Sparks, R.S.J. and Matthews, S.J. (1998) Evolution of Lascar Volcano, Northern Chile. J. Geol. Soc., Lond., 155, 89–104.CrossRefGoogle Scholar
Haughton, D.R., Roeder, P.L. and Skinner, B.J. (1974) Solubility of sulfur in mafic magmas. Econ. Geol., 69, 451–67.CrossRefGoogle Scholar
Katsura, T., Nagashima, S. (1974) Solubility of sulfur in some magmas at 1 atmosphere. Geochim. Cosmochim. Acta, 38, 517–31.CrossRefGoogle Scholar
Kucha, H. and Stumpfl, E.F. (1992) Thiosulphates as precursors of banded sphalerite and pyrite at Bleiberg, Austria. Mineral. Mag., 56, 165–72.CrossRefGoogle Scholar
Kucha, H., Wouters, R. and Arkens, O. (1989) Determination of sulfur and iron valence by microprobe. Scanning Microsc., 3, 89–97.Google Scholar
Lindsley, D.H. and Frost, B.R. (1992) Equilibria among Fe-Ti oxides, pyroxenes, olivine, and quartz: Part I. Theory. Amer. Mineral., 77, 987–1003.Google Scholar
Luhr, J.F. (1990) Experimental phase relations of water- and sulfur-saturated arc magmas and the 1982 eruptions of El Chichon volvano. J. Petrol., 31, 1071–114.CrossRefGoogle Scholar
Matthews, S.J., Jones, A.P. and Gardeweg, M.C. (1994a) Lascar Volcano, Northern Chile; Evidence for Steady-State Disequilibrium. J. Petrol., 35, 401–32.CrossRefGoogle Scholar
Matthews, S.J., Jones, A.P. and Beard, A.D. (1994b) Buffering of melt oxygen fugacity by sulphur redox reactions in calc-alkaline magmas. J. Geol. Soc., Lond., 151, 815–23.CrossRefGoogle Scholar
Matthews, S.J., Marquillas, R.A., Kemp, A.J., Grange, F.K. and Gardeweg, M.C. (1996) Active Skarn Formation Beneath Lascar Volcano, Northern Chile: A Petrographic and Geochemical Study of Xenoliths in Eruption Products. J. Metam. Geol., 14, 509–30.CrossRefGoogle Scholar
Matthews, S.J., Gardeweg, M.C. and Sparks, R.S.J. (1997) The 1984 to 1996 cyclic activity of Lascar volcano, northern Chile: cycles of dome growth, dome subsidence, degassing and explosive eruptions. Bull. Volcanol., 59, 72–82.CrossRefGoogle Scholar
Nilsson, K. and Peach, C. (1993) Sulfur speciation, oxidation state, and sulfur concentration in backarc magmas. Geochim. Cosmochim. Acta, 57, 3807–13.CrossRefGoogle Scholar
Wallace, P.J. and Carmichael, I.S.E. (1994) S speciation in submarine basaltic glasses as determined by measurements of SKa X-ray wavelength shifts. Amer. Mineral., 79, 161–7.Google Scholar