AGE OF XENOLITH-BEARING BASALTS AND MANTLE EVOLUTION IN THE BAIKAL RIFT ZONE
I.V. Ashchepkov, S.V. Travin, A.I. Saprykin, L. Andre*, P.A. Gerasimov, and O.S. Khmel'nikova
United Institute of Geology, Geophysics and Mineralogy, Siberian Branch of the RAS,
3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
* Royal Museum of Central Africa, Tervuren, Belgium
Keywords: Basalt, rift zone, melting, mantle, peridotites, pyroxenites, melt, differentiation, geochemistry, thermobarometry, inductively bound mass-plasma
Pages: 1121-1149
Abstract
Five age stages of xenolith-bearing basalts of the Vitim and Khamar-Daban lava plateaus have been recognized by K-Ar dating. Thermobarometry of the basalt melts suggests deep levels of magma derivation at the initial and final stages. The PT paths of the melt upwelling in the period of generation of lava plateau are steeper than the PT paths of hydrous lavas during the initial and final periods of volcanic activity. Temperature sections for a mineral (rock) vary quickly in time. For the Vitim Plateau, three zones of melt concentration have been expressed at Stage I (18-16 Ma): 25-27 kbar, 1300-1100
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