The evolution of high-alumina basalts of the Klyuchevskoy volcano, Kamchatka, Russia, based on microprobe analyses of mineral inclusions

• Published in: Journal of Volcanology and Geothermal Research
• Main Author: Ozerov Alexei Y.
• Format: Text
• Language: English
• Published: 2000
• Subjects: 38.37.25 Вулканология; Ключевской; Kamchatka
• Online Access: http://repo.kscnet.ru/2569/; http://repo.kscnet.ru/2569/1/my_2000_f_en_JVGR.pdf; http://www.sciencedirect.com/science/article/pii/S0377027399001183

The origin of calc-alkaline high-alumina basalts (HAB) of the Klyuchevskoy volcano, Kamchatka, was examined using electron microprobe analyses of phenocrysts and mineral phases included in the phenocrysts. Continuous trends on major-element variation diagrams suggest the HAB were derived from high-magnesia basalt (HMB) by fractional crystallization. Phenocrysts in the HAB are strongly zoned: olivine (Mg# 91–64), clinopyroxene (Wo45–38En40–51Fs5–20) and chrome—spinel/magnetite inclusions in them (Cr2O3 45–0 wt.%, TiO2 0.5–11%). Microprobe analyses of minerals included in the phenocrysts provide additional constraints on the mineral crystallization trends in the HAB. Fe/Mg partitioning data, when applied to the phenocrysts cores, show they crystallized from a HMB. The similarity of phenocryst core compositions in HAB with those in HMB strongly suggests a genetic relationship between the two magma types.