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resolved degassing analysis of volcanic crystalline and vitreous rocks gives detailed information about volatile compounds
in the melt. Aspecial high-temperature mass-spectrometry device in combination with a thermo-balance allows
a quantitative determination of different volatile species. It enables a differentiation between the primary gas
content in the magma and the gas released from decomposition of secondary alteration products. The gas release
profiles give the following indications: i) during the littoral explosions of Pahoehoe lava the content of volatiles is
not changed by interaction with air or sea water; ii) the degassing profiles of vitreous black sand verify the primary
content of volatiles in the erupted melt, only CO2 was detected; iii) the oxygen release profile gives significant indications
for oxygen undersaturation of the erupted magma; iv) remelting of black sand in air at 1450°C for 0.45 h
causes an oxygen saturation of the basaltic melt; v) remelting of black sand in argon atmosphere confirms the oxygen
undersaturation of the melt; vi) remelting of black sand-black shale mixtures affects a significant change in the
degassing profiles, especially in CO2-release. With the first investigations we can demonstrate that gas release
curves of volcanic rocks are qualified for a) detection of the primary gas content of erupted magma; b) detection of
alteration processes of the igneous glass; c) detection of contamination of the magma with adjacent rocks.
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