A composition-independent quantitative determination of the water content in silicate glasses and silicate melt inclusions by confocal Raman spectroscopy

Abstract

A composition-independent quantitative determination of the water content in silicate glasses and silicate melt inclusions by confocal Raman spectroscopy Abstract A new approach was developed to measure the water content of silicate glasses using Raman spectroscopy, which is independent of the glass matrix composition and structure. Contrary to previous studies, the compositional range of our studied silicate glasses was not restricted to rhyolites, but included andesitic, basaltic and phonolitic glasses. We used 21 glasses with known water contents for calibration. To reduce the uncertainties caused by the baseline removal and correct for the influence of the glass composition on the spectra, we developed the following strategy: (1) application of a frequency-dependent intensity correction of the Raman spectra; (2) normalization of the water peak using the broad T-O and T-O-T vibration band at 850-1250 cm )1 wavenumbers (instead of the low wavenumber T-O-T broad band, which appeared to be highly sensitive to the FeO content and the degree of polymerization of the melt); (3) normalization of the integrated Si-O band area by the total number of tetrahedral cations and the position of the band maximum. The calibration line shows a ±0.4 wt% uncertainty at one relative standard deviation in the range of 0.8-9.5 wt% water and a wide range of natural melt compositions. This method provides a simple, quick, broadly available and cost-effective way for a quantitative determination of the water content of silicate glasses. Application to silicate melt inclusions yielded data in good agreement with SIMS data.

Diffusive fractionation of H2O and CO2 during magma degassing

“…On the other hand, the 1080 cm -1 peak was very weak and was almost hidden within a strong peak located from 800-1200 cm -1 , which was the sum of several Raman bands that corresponded to different bridging and non-bridging T-O vibrations in the glass structure (Zajacz et al, 2005). Recently, various techniques have been developed to M A N U S C R I P T…”

Determination of fluid/melt partition coefficients by LA-ICPMS analysis of co-existing fluid and silicate melt inclusions: Controls on element partitioning

“…Water contents of melt inclusions were analyzed by Raman spectroscopy following the method of Zajacz et al (2005). However, most reheated inclusions were highly fluorescent under the Raman probe, preventing a reliable application of this approach.…”

LA-ICPMS analyses of silicate melt inclusions in co-precipitated minerals: Quantification, data analysis and mineral/melt partitioning

“…Furthermore, simultaneous application of LA-ICPMS and SIMS/EPMA allows assessment of potential compositional changes during heating experiments. As H 2 O contents can be determined by Raman spectroscopy (Zajacz et al, 2005;Behrens et al, 2006;Di Muro et al, 2006;Thomas et al, 2006) all major and trace elements (except for CO 2 ) can be analyzed with commonly available LA-ICPMS, electron microprobe, and Raman spectroscopy.…”