A 2.4-year controlled-cooling-rate experiment was carried out to investigate the dependence of hydrous species concentrations in rhyolitic melt on cooling rate. The experiment allows us to obtain speciation for a cooling rate of 1.68 · 10 6 K/s, extending previous experimental data by two orders of magnitude. Furthermore, a viscosity as high as 10 Pa s is inferred for this hydrous rhyolitic mel...

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...

Abstract The low-grade metamorphic early Paleozoic basement of the Veitsch area presents a wide variety sedimentary facies domains. first domain consists thick metadacites Middle Ordovician age (Blasseneck Porphyroid), overlain by fine-grained metaclastics Rad Formation (Late to Silurian) and Devonian limestones calcitic marbles (Kaiserstein Kaskögerl Formation, respectively). Rhyolitic dacitic...

This work presents the volcanic geology of easternmost sector Trans-Mexican Volcanic Belt, including Serdán-Oriental basin and Cofre de Perote-Citlaltépetl range, two contrasting Quaternary fields. The first comprises dominant monogenetic volcanism bimodal composition isolated rhyolitic domes tuff rings, basaltic andesite maar volcanoes, cinder lava cones, an active caldera complex (Los Humeros...

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 ...

This study explores the photosynthetic microbial colonization of rhyolitic ignimbrites in Lomas de Tilocalar, a hyper-arid region of the Atacama Desert, Chile. Colonization appeared in the form of a green layer a few millimeters beneath the ignimbrite surface. Some ignimbrite rocks revealed two distinct micromorphological areas of identical mineralogical and chemical composition but different t...

Paektu volcano (Changbaishan) is a rhyolitic caldera that straddles the border between the Democratic People's Republic of Korea and China. Its most recent large eruption was the Millennium Eruption (ME; 23 km3 dense rock equivalent) circa 946 CE, which resulted in the release of copious magmatic volatiles (H2O, CO2, sulfur, and halogens). Accurate quantification of volatile yield and compositi...

This paper presents a new technique to measure water concentrations in small volcanic glasses such as melt inclusions. The technique uses Fourier transform infrared (FT-IR) micro-reflectance spectroscopy, and thus does not require a doubly polished sample. To enhance the signal-to-noise (S/N) ratio, a vacuum pump and a narrow-band mercury-cadmium-telluride (MCT) detector were introduced into th...