PETROLOGY OF BASANITIC LAVAS OF THE DAUR-HENTIYN RANGE (P-Tconditions of formation, crystallization sequence, and sources of material)
A.Ya. Medvedev1, E.I. Demonterova2, A.A. Karimov1, V.A. Belyaev1
1Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia
2Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia
Keywords: Cenozoic volcanism, isotope composition, mineral composition, geochemical composition
Abstract
We performed a comprehensive study of basanites from the Daur-Hentiyn Range and present the first data on their Sr and Nd isotope and mineral compositions (electron probe microanalysis). The study has shown that the basanites are chemically similar to the volcanic rocks of the South Baikal volcanic area (SBVA ) and are slightly different from oceanic island basalts in higher contents of Ba, Th, La, and Sr. The crystallization temperatures and pressures for the Fo0.85 olivine-melt equilibrium have been estimated, 1186-1137 °C, 1.09-1.06 GPa, and the sequence of mineral crystallization has been established. The obtained Sr and Nd isotope data indicate that the basanitic magmas were generated from material with PREMA and EMI isotope parameters.
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