F. D. Baker, C. Baker, and . Freda, Eutectic crystallization in the undercooled Orthoclase-Quartz-H<SUB>2</SUB>O system: experiments and simulations, European Journal of Mineralogy, vol.13, issue.3, pp.453-466, 2001.
DOI : 10.1127/0935-1221/2001/0013-0453

R. L. Baker, M. J. Baker, and . Rutherford, The effect of dissolved water on the oxidation state of silicic melts, Geochimica et Cosmochimica Acta, vol.60, issue.12, pp.2179-2187, 1996.
DOI : 10.1016/0016-7037(96)00090-7

. Berry, XANES calibrations for the oxidation state of iron in a silicate glass, American Mineralogist, vol.88, issue.7, pp.967-977, 2003.
DOI : 10.2138/am-2003-0704

. Wilke, The effect of water activity on the oxidation and structural state of Fe in a ferrobasaltic melt, Geochimica Cosmochimica Acta, vol.69, pp.5071-5085, 2005.

S. A. Burgisser, B. Burgisser, and . Scaillet, Redox evolution of a degassing magma rising to the surface, Nature, vol.80, issue.7124, pp.194-197, 2007.
DOI : 10.1007/BF00306429

URL : https://hal.archives-ouvertes.fr/hal-00125264

P. P. Candela and . Candela, The evolution of aqueous vapor from silicate melts: Effect on oxygen fugacity, Geochimica et Cosmochimica Acta, vol.50, issue.6, pp.1205-1211, 1986.
DOI : 10.1016/0016-7037(86)90403-5

I. S. Carmichael and . Carmichael, The redox states of basic and silicic magmas: a reflection of their source regions?, Contributions to Mineralogy and Petrology, vol.248, issue.2, pp.129-141, 1991.
DOI : 10.1007/BF00306429

. Castro, Timescales of spherulite crystallization in obsidian inferred from water concentration profiles, American Mineralogist, vol.93, issue.11-12, pp.1816-1822, 2008.
DOI : 10.2138/am.2008.2904

URL : https://hal.archives-ouvertes.fr/insu-00363340

H. R. Colony, A. D. Colony, and . Howard, Observations on spherulites, American Mineralogist, vol.19, pp.515-524, 1934.

. Cottrell, High-precision determination of iron oxidation state in silicate glasses using XANES, Chemical Geology, vol.268, issue.3-4, 2009.
DOI : 10.1016/j.chemgeo.2009.08.008

. Donald, High-iron ferric glass, High-iron ferric glass, pp.539-543, 2006.
DOI : 10.1016/j.jnoncrysol.2005.11.042

. Gaillard, The effect of water and fO2 on the ferric???ferrous ratio of silicic melts, Chemical Geology, vol.174, issue.1-3, pp.255-273, 2001.
DOI : 10.1016/S0009-2541(00)00319-3

URL : https://hal.archives-ouvertes.fr/hal-00089731

. Gaillard, Kinetics of iron oxidation-reduction in hydrous silicic melts, American Mineralogist, vol.87, issue.7, pp.829-837, 2002.
DOI : 10.2138/am-2002-0704

URL : https://hal.archives-ouvertes.fr/hal-00072812

. Gaillard, Rate of hydrogen???iron redox exchange in silicate melts and glasses, Geochimica et Cosmochimica Acta, vol.67, issue.13, pp.2427-2441, 2003.
DOI : 10.1016/S0016-7037(02)01407-2

. Gaillard, Experimental determination of activities of FeO and Fe2O3 components in hydrous silicic melts under oxidizing conditions, Geochimica et Cosmochimica Acta, vol.67, issue.22, pp.4389-4409, 2003.
DOI : 10.1016/S0016-7037(03)00376-4

URL : https://hal.archives-ouvertes.fr/hal-00069333

. Gaillard, and Fe-bearing silicate melts, American Mineralogist, vol.88, issue.2-3, pp.308-315, 2003.
DOI : 10.2138/am-2003-2-308

URL : https://hal.archives-ouvertes.fr/hal-00069454

R. C. Geschwind, M. J. Geschwind, and . Rutherford, Crystallization of microlites during magma ascent: the fluid mechanics of 1980???1986 eruptions at Mount St Helens, Bulletin of Volcanology, vol.63, issue.5, pp.356-370, 1995.
DOI : 10.1007/BF00301293

D. K. Hess and D. B. Hess, Viscosities of hydrous leucogranitic melts: a non-Arrhenian model, American Mineralogist, vol.81, pp.1297-1300, 1996.

J. R. Holloway and . Holloway, Redox reactions in seafloor basalts: possible insights into silicic hydrothermal systems, Chemical Geology, vol.210, issue.1-4, pp.225-230, 2004.
DOI : 10.1016/j.chemgeo.2004.06.009

C. V. Kress, I. S. Kress, and . Carmichael, The compressibility of silicate liquids containing Fe2O3 and the effect of composition, temperature, oxygen fugacity and pressure on their redox states, Contributions to Mineralogy and Petrology, vol.85, issue.1-2, pp.82-92, 1991.
DOI : 10.1007/BF00307328

C. R. Manley and . Manley, Extended cooling and viscous flow of large, hot rhyolite lavas: implications of numerical modeling results, Journal of Volcanology and Geothermal Research, vol.53, issue.1-4, pp.27-46, 1992.
DOI : 10.1016/0377-0273(92)90072-L

F. C. Manley, J. H. Manley, and . Fink, Internal textures of rhyolite flows as revealed by research drilling, Geology, vol.15, issue.6, pp.549-552, 1987.
DOI : 10.1130/0091-7613(1987)15<549:ITORFA>2.0.CO;2

E. A. Mathez and . Mathez, Influence of degassing on oxidation states of basaltic magmas, Nature, vol.278, issue.5976, pp.371-374, 1984.
DOI : 10.1038/310371a0

. Métrich, Redox state of iron in peralkaline rhyolitic glass/melt: X-ray absorption micro-spectroscopy experiments at high temperature, Chemical Geology, vol.231, issue.4, pp.231-350, 2006.
DOI : 10.1016/j.chemgeo.2006.02.001

. Moore, The effect of dissolved water on the oxidation state of iron in natural silicate liquids, Contributions to Mineralogy and Petrology, vol.85, issue.2, pp.170-179, 1995.
DOI : 10.1007/BF00287114

. Moriizumi, Colorchange processes of a plinian pumice and experimental constraints on color-change kinetics in air of an obsidian, Bulletin of Volcanology, vol.10, pp.445-0080202, 1007.

R. F. Mueller and . Mueller, Oxidative capacity of magmatic components, American Journal of Science, vol.270, issue.3, pp.236-243, 1971.
DOI : 10.2475/ajs.270.3.236

. Newman, Measurement of water in rhyolitic glasses: calibration of an infrared spectroscopic technique, American Mineralogist, vol.71, pp.1527-1541, 1986.

L. C. Peck and . Peck, Systematic analysis of silicates, Bulletin, vol.1170, p.80, 1964.

W. M. Sato, T. L. Sato, and . Wright, Oxygen Fugacities Directly Measured in Magmatic Gases, Science, vol.153, issue.3740, pp.1103-1105, 1966.
DOI : 10.1126/science.153.3740.1103

M. Sato and . Sato, Oxygen fugacity of basaltic magmas and the role of gas-forming elements, Geophysical Research Letters, vol.105, issue.8481-8493, pp.447-449, 1978.
DOI : 10.1029/GL005i006p00447

G. T. Sisson, T. L. Sisson, and . Grove, Experimental investigations of the role of H2O in calc-alkaline differentiation and subduction zone magmatism, Contributions to Mineralogy and Petrology, vol.3, issue.4, pp.143-166, 1993.
DOI : 10.1007/BF00283225

. Smith, Growth of megaspherulites in a rhyolitic vitrophyre, American Mineralogist, vol.86, issue.5-6, pp.589-600, 2001.
DOI : 10.2138/am-2001-5-601

. Stasiuk, Degassing during magma ascent in the Mule Creek vent (USA), Degassing during magma ascent in the Mule Creek vent (USA), pp.117-130, 1993.
DOI : 10.1007/s004450050130

. Stevenson, Physical volcanology and emplacement history of the Ben Lomond rhyolite lava flow, Taupo Volcanic Centre, New Zealand, New Zealand Journal of Geology and Geophysics, vol.13, issue.3, pp.345-358, 1994.
DOI : 10.1029/JB093iB06p06503

E. S. Stolper and . Stolper, The speciation of water in silicate melts, Geochimica et Cosmochimica Acta, vol.46, issue.12, pp.2609-2620, 1982.
DOI : 10.1016/0016-7037(82)90381-7

. Swanson, Crystallization history of Obsidian Dome, Inyo Domes, California, Bulletin of Volcanology, vol.83, issue.3, pp.161-176, 1989.
DOI : 10.1007/BF01067953

C. H. Tuffen, J. M. Tuffen, and . Castro, The emplacement of an obsidian dyke through thin ice, Journal of Volcanology and Geothermal Research, 2009.

. Tuffen, in review. The thermal effects of spherulite crystallization in rhyolitic lava, Earth and Planetary Science Letters

. Watkins, Diffusion-controlled spherulite growth in obsidian inferred from H2O concentration profiles, Contributions to Mineralogy and Petrology, vol.63, issue.15, pp.163-172, 2009.
DOI : 10.1007/s00410-008-0327-8

. Westrich, Degassing of rhyolitic magma during ascent and emplacement, Journal of Geophysical Research, vol.66, issue.B6, pp.6503-6511, 1988.
DOI : 10.1029/JB093iB06p06503

. Wilke, Determination of the iron oxidation state in basaltic glasses using XANES at the K-edge, Chemical Geology, vol.220, issue.1-2, pp.143-161, 2005.
DOI : 10.1016/j.chemgeo.2005.03.004

F. E. Wright and . Wright, Obsidian from Hrafntinnuhryggur, Iceland: its lithopliysae. and surface markings, Geological Society of America Bulletin, vol.26, issue.1, pp.255-286, 1915.
DOI : 10.1130/GSAB-26-255