The valence and speciation of sulfur in glasses by X-ray absorption spectroscopy

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doi: 10.2113/gscanmin.39.2.331
Authors:Paris, Eleonora; Giuli, Gabriele; Carroll, Michael R.; Davoli, Ivan
Author Affiliations:Primary:
Universita di Camerino, Dipartamento di Scienze della Terra, Camerino, Italy
Queen's University, Canada
Universita di Roma, Italy
Volume Title:Phase equilibria in basaltic systems; a tribute to Peter L. Roeder
Volume Authors:Canil, Dante, editor; Jamieson, Heather E.; Martin, Robert F.
Source:Phase equilibria in basaltic systems; a tribute to Peter L. Roeder, edited by Dante Canil, Heather E. Jamieson and Robert F. Martin. The Canadian Mineralogist, Vol.39(Part 2), p.331-339. Publisher: Mineralogical Association of Canada, Ottawa, ON, Canada. ISSN: 0008-4476
Publication Date:2001
Note:In English with French summary. 39 refs.; illus., incl. 3 tables
Summary:The geochemical behavior of sulfur in magmas depends strongly on the oxidation state of sulfur, but this is not easily determined by standard analytical methods. We have measured XANES absorption spectra at the sulfur K-edge and have found that such measurements are useful to characterize the oxidation state and speciation of sulfur in silicate glasses of geological relevance. Measured spectra of a set of reference minerals show the effects of different oxidation states and coordination numbers of sulfur; there is large shift in energy (∼10-12 eV) of the sulfur K-edge between S2- and S6+. This large and easily detectable difference makes possible the measurement of the valence of sulfur in unknown samples by measuring the shift in energy of the absorption edge. This approach is applicable to both crystalline and glassy materials, and useful results have been obtained on samples with as little as 450 ppm S. We have used XANES measurements to characterize oxidation state and speciation of sulfur in a set of natural and synthetic sulfur-bearing glasses. The samples cover a range of composition from basaltic to almost rhyolitic, and some were synthesized over a range of pressure, temperature and oxygen fugacity; glass S content varies between 450 and 3000 ppm. XANES analyses, carried out in fluorescence mode at LURE, allowed determination of the sulfur oxidation state in all of the samples and clearly show that some samples contain a mixture of S2- and S6+; no other sulfur species were observed. Quantitative determination of the abundance of sulfide and sulfate shows good agreement with independent measurements based on electron-microprobe determination of the wavelength shift of sulfur Kα X-rays.
Subsections:Analytical geochemistry
Subjects:Behavior; Electron probe data; Fugacity; Geochemistry; Glasses; Igneous rocks; Magmas; Measurement; Melts; Oxidation; Oxygen; Solubility; Spectra; Sulfides; Sulfur; Temperature; Valency; Volcanic rocks; Wavelength; X-ray spectra; XANES spectra
Abstract Numbers:02M/753
Record ID:2002010841
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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