Glasses Tech

March 8, 2010

Analytical techniques for volatiles: A case study using intermediate (andesitic) glasses

Filed under: Glasses 2002 — admin @ 4:28 am

Eyeglasses

Small-scale analyses of volatiles in minerals and glasses provide information on how volatiles influence high-temperature geologic processes and low-temperature alteration processes. Four techniques for determining the C-O-H volatile contents of andesitic glasses are compared: manometry, secondary ion mass spectrometry, micro-Fourier transform infrared spectroscopy, and a technique where the H2O content is calculated using the difference between electron microprobe analysis totals and 100% sum. We present a method to determine the H content of a wide range of glass and mineral compositions using secondary ion mass spectrometry and a model for calibration factors. The extinction coefficients for H-O volatile contents in intermediate composition synthetic glasses are determined, and it is demonstrated that C-O speciation changes as total H2O content increases, with molecular CO2 decreasing, CO32– increasing, and carbonate peak splitting increasing. For glasses with low H2O content and oxy-substituted minerals, the methods of choice for volatile analysis are secondary ion mass spectrometry or micro-Fourier transform infrared spectroscopy.

P.L. King1,*, T.W. Vennemann2, J.R. Holloway1,3, R.L. Hervig1,4, J.B. Lowenstern5 and J.F. Forneris1
1 Geology Department, Arizona State University, Tempe, Arizona 85287, U.S.A.
2 Institut Geochemie, Wilhelmstr. 56, D-72076, Tübingen, Germany
3 Chemistry Department, Arizona State University, Tempe, Arizona 85287, U.S.A.
4 Center for Solid State Science, Arizona State University, Tempe, Arizona 85287, U.S.A.
5 U.S. Geological Survey, MS 910, 345 Middlefield Road, Menlo Park, California 94025, U.S.A.

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