Explosive Basaltic Volcanism of the Chikurachki Volcano (Kurile Arc
Journal of Volcanology and Geothermal Research 147 (2005) 203–232 www.elsevier.com/locate/jvolgeores Explosive basaltic volcanism of the Chikurachki Volcano (Kurile arc, Russia): Insights on pre-eruptive magmatic conditions and volatile budget revealed from phenocryst-hosted melt inclusions and groundmass glasses A.A. Gurenkoa,b,*, A.B. Belousovc,d, R.B. Trumbullb, A.V. Soboleva,e aMax Planck Institute for Chemistry, Geochemistry, P.O. Box 3060, 55020 Mainz, Germany bGeoForschungsZentrum Potsdam, Section 4.2, Telegrafenberg, 14473 Potsdam, Germany cInstitute of Marine Geology and Geophysics, 693022 Yuzno-Sakhalinsk, Russia dInstitute of Volcanic Geology and Geochemistry, 683006 Petropavlovsk-Kamchatsky, Russia eVernadsky Institute of Geochemistry and Analytical Chemistry, 117975 Moscow, Russia Received 13 December 2004; accepted 6 April 2005 Abstract Highly explosive eruptions of basaltic composition are relatively rare and poorly understood, yet they may be quite important in terms of atmospheric impact because of the generally much higher concentrations of S in basaltic systems compared with the typical explosive felsic eruptions. We have determined concentrations of H2O, major, trace and volatile (S, Cl) elements by EPMA and SIMS from melt inclusions and groundmass glasses of the 1986, 1853 and prehistoric explosive eruptions of basaltic magmas from the Chikurachki volcano, northern Kurile arc. Melt inclusions are hosted by olivine (Fo72–78), orthopyroxene (mg#=72–75), clinopyroxene (mg#=71–77) and plagioclase (An74–96) phenocrysts. Estimated crystallization conditions were in the range from 910 to 1180 8C at less than 400 MPa total pressure and oxygen fugacity of NNO+1 to +2 log units. Inclusion glasses are basaltic to andesitic in composition.
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