caa a22 4500 477062318 CHVBK 20180405111404.0 cr unu---uuuuu 170330e19960701xx s 000 0 eng 10.1007/s004450050114 doi (NATIONALLICENCE)springer-10.1007/s004450050114 Rhyolite magma degassing: an experimental study of melt vesiculation [Elektronische Daten] [N. S. Bagdassarov, D. B. Dingwell, M. C. Wilding]  The vesiculation of a peralkaline rhyolite melt (initially containing ∼0.14 wt.% H2O) has been investigated at temperatures above the rheological glass transition (T g≈530  °C) by (a) in situ optical observation of individual bubble growth or dissolution and (b) dilatometric measurements of the volume expansion due to vesiculation. The activation energy of the timescale for bubble growth equals the activation energy of viscous flow at relatively low temperatures (650-790  °C), but decreases and tends towards the value for water diffusion at high temperatures (790-925  °C). The time dependence of volume expansion follows the Avrami equation ΔV (t)∼{1-exp [-(t/τav) n ]} with the exponent n=2-2.5. The induction time of nucleation and the characteristic timescale (τav) in the Avrami equation have the same activation energy, again equal to the activation energy of viscous flow, which means that in viscous melts (Peclet number <1) the vesiculation (volume expansion), the bubble growth process, and, possibly, the nucleation of vesicles, are controlled by the relaxation of viscous stresses. One of the potential volcanological consequences of such behavior is the existence of a significant time lag between the attainment of a super-saturated state in volatile-bearing rhyolitic magmas and the onset of their expansion. Springer-Verlag Berlin Heidelberg, 1995 Key words Rhyolite nationallicence Vesiculation nationallicence Kinetic nationallicence Water nationallicence Diffusion nationallicence Degassing nationallicence Bagdassarov N. S. Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany, DE aut Dingwell D. B. Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany, DE aut Wilding M. C. Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany, DE aut https://doi.org/10.1007/s004450050114 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s004450050114 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bagdassarov N. S. Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany, DE aut NATIONALLICENCE 700 1- Dingwell D. B. Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany, DE aut NATIONALLICENCE 700 1- Wilding M. C. Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany, DE aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer