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G-Cubed: Geochemistry, Geophysics, Geosystems; an electronic journal of the Earth sciences

 

Keywords

  • chlorine
  • silicate melt
  • XANES
  • speciation
  • synthetic
  • Lau

Index Terms

  • Mineralogy and Petrology: Experimental mineralogy and petrology
  • History of Geophysics: Volcanology, geochemistry, and petrology
  • Geochemistry: Magma genesis and partial melting
Abstract
Cited By
 

Abstract

A preliminary investigation of chlorine XANES in silicate glasses

K. A. Evans

Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia

J. A. Mavrogenes

Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia

H. S. O'Neill

Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia

N. S. Keller

Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia

L.-Y. Jang

National Synchrotron Radiation Research Centre, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan

Chlorine speciation in silicate melts affects volatile exsolution, rheology, and thermodynamic properties of the melt but is poorly known. X-Ray Absorption Near Edge Structure (XANES) spectra have been used to investigate Cl speciation in 26 silicate glasses and to test the hypothesis that Cl in silicate melts is hosted by species that combine Cl and network-modifying cations such as Ca and Mg. Results indicate that Cl in CMAS (CaO-MgO-Al2O3-SiO2) plus Na2O, K2O, or MnO silicate glasses exists as a combination of Ca-Cl x and Mg-Cl x species or, possibly, as mixed Ca-Mg y -Cl x species. The geometry and stoichiometry of the proposed species is unknown, but there are similarities between spectra from Ca-bearing melts and the spectra of hydrated CaCl2.2H2O, suggesting that the Ca-Cl x species could have a salt-like atomic arrangement and ionic bonding. Further investigations using XANES, alternative spectroscopic techniques, and forward modeling approaches are required to distinguish between these possibilities.

Received 13 February 2008; accepted 1 August 2008; published 4 October 2008.

Citation: Evans, K. A., J. A. Mavrogenes, H. S. O'Neill, N. S. Keller, and L.-Y. Jang (2008), A preliminary investigation of chlorine XANES in silicate glasses, Geochem. Geophys. Geosyst., 9, Q10003, doi:10.1029/2008GC002157.

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