origin of olivine phenocrysts and mantle source of magnesian basalts from the kharchinsky volcano (the central kamchatka depression)
V.S. Sekisova1, S.Z. Smirnov1, D.V. Kuzmin1, A.Ya. Shevko1, M.P. Gora1
1V.S. Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk, Russia
2Novosibirsk State University, 630090, Novosibirsk, Pirogova st., 1, Russia
Keywords: Kamchatka, CKD, the Kharchinsky volcano, basalts, olivine, melt inclusions
Abstract
The article presents new data on the formation conditions of basalts and basaltic andesites of the Kharchinsky volcano (the Central Kamchatka Depression, CKD). It is shown that the liquidus association is represented by olivine (Fo91) and Cr-spinel, which crystallized in oxidized conditions NNO+0.4 – NNO+1.5 at temperatures of 1110 – 1210°C. Melt inclusion in olivine phenocrysts study gives opportunity to reconstruct the parental melts for basalts and basaltic andesites. These melts have Mg-high (Mg# ≈ 76), Al-low and Ca-low mafic compositions enriched in volatiles. Water content in melts could reach up to 5.5 wt.%. These melts have a peridotite source; also, pyroxenite component admixture could take place. Crystallization of melts could occur in several intermediate chambers (up to 1.5, at 5-7 and 11-13 kbar).
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