HIGH-K BASALTIC TRACHYANDESITE XENOLITHS IN PYROCLASTIC DEPOSITS FROM THE BEZYMIANNY VOLCANO (Kamchatka)
V.O. Davydova1, P.Yu. Plechov1,2, V.D. Shcherbakov1, A.B. Perepelov3
1Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119991, Russia
2Fersman Mineralogical Museum, Russian Academy of Sciences, Leninsky pr.18, korp. 2, Moscow, 119071, Russia
3A.P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, 664033, Irkutsk, Russia
Keywords: High-K basaltic trachyandesite, xenoliths, Bezymianny Volcano, Tolbachik Volcano
Abstract
Bezymianny is an active andesitic volcano of the Klyuchevskaya group, and its eruptive products are xenolith- and enclave-bearing basaltic andesites and dacites. Here we report the first occurrence of clinopyroxene-plagioclase high-potassium basaltic trachyandesite xenoliths (51.84-53.00 wt.% SiO2, 0.95-1.95 wt.% K2O) crystallized in the temperature range 1120-840 °C in products of modern eruptions (2007, 2011, 2012). Basaltic trachyandesite differ systematically in petrologic and geochemical characteristics from all previously studied rocks from the Bezymianny Volcano. They correspond to the clinopyroxene-plagioclase porphyry rocks from the foot of the Tolbachik volcanoes.
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