Measurement of water in rhyolitic glasses: Calibration of an infrared spectroscopic technique
نویسندگان
چکیده
A series of natural rhyolitic obsidians were analyzed for their total water contents by a vacuum extraction technique. The grain size of the crushed samples can significantly affect these analyses. Coarse powders must be used in order to avoid surface-correlated water. These analyses were used to calibrate infrared spectroscopic measurements of water in glass using several infrared and near-infrared absorption bands. We demonstrate that infrared spectroscopy can yield precise determinations of not only total dissolved water contents, but also the concentrations of individual H-bearing species in natural and synthetic rhyolitic glasses on spots as small as a few tens of micrometers in diameter.
منابع مشابه
H2o in Rhyolitic Glasses and Melts: Measurement, Speciation, Solubility, and Diffusion
Dissolved H2O in silicate melts and glasses plays a crucial role in volcanic eruptions on terrestrial planets and affects glass properties and magma evolution. In this paper, major progress on several aspects of the H2O-melt (or glass) system is reviewed, consistency among a variety of data is investigated, discrepancies are evaluated, and confusion is clarified. On the infrared measurement of ...
متن کاملThe speciation of dissolved water in rhyolitic melt
Concentrations of water molecules and hydroxyl groups have been measured in rhyolitic glasses with 0.5% to 5.0% H2Ot using infrared spectroscopy at room temperature. The glasses were cooled at ;10 C/s after having been held at 400 to 600C, for sufficient time for the equilibrium distribution of species to have been reached. The speciation of water in samples with greater than 2.5 wt.% total dis...
متن کاملReconciliation of experimental results on H2O speciation in rhyolitic glass using in-situ and quenching techniques
In order to resolve the controversy over how to interpret experimental H2O speciation results using in-situ and quenching techniques, we have carried out an infrared spectroscopic study to determine whether the molecular H2O (5230 cm ) and OH (4520 cm ) band intensity variation with measurement temperature below glass transition is owing to species interconversion or to the temperature dependen...
متن کاملHydrous species geospeedometer in rhyolite: Improved calibration and application
The hydrous species geospeedometer is based on the homogeneous interconversion reaction between molecular H2O species and OH species in silicate melts and glasses. Here we report new data for the calibration of the geospeedometer in rhyolitic glass, extending the coverage of quench rate to 94 K/s and of H2Ot to 7.7 wt.% by using a piston-cylinder apparatus at low pressures (200–500 MPa) to prev...
متن کاملDiffusion of water in rhyolitic glasses.
Water dehydration experiments on rhyolitic glasses have been carried out at 400-550 degrees C under a N2 atmosphere. Concentration profiles of both H2O molecules and OH groups were measured by Fourier transform infrared spectroscopy. As found in previous studies of water diffusion in rhyolitic melts, the measured total water concentration profiles do not match expectations based on a single c...
متن کامل