UPPER MANTLE BENEATH THE UDOKAN VOLCANIC FIELD: STUDY OF PERIDOTITE XENOLITHS IN LATE CENOZOIC BASALTOIDS
K.D. Litasov1,2, Yu.D. Litasov1, A.V. Ivanov3, S.V. Rasskazov3, H. Yurimoto4, E.I. Demonterova3, V.V. Sharygin5, and V.G. Mal'kovets5,6
1Institute of Geology, Siberian Branch of the RAS,
3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
2 Institute of Mineralogy, Petrology and Economic Geology, Tohoku University, Sendai, Japan
3 Institute of the Earth's Crust, Siberian Branch of the RAS,
128 ul. Lermontova, Irkutsk, 664033, Russia
4 Tokyo Institute of Technology, Tokyo, Japan
5 Institute of Mineralogy and Petrography, Siberian Branch of the RAS,
3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
6 Department of Geosciences, Macquarie University, Sydney, Australia
Keywords: Upper mantle, xenolith, peridotite, pyroxenite, clinopyroxene, trace elements
Pages: 134-155
Abstract
Cr-diopside group mantle xenoliths from Late Cenozoic basaltoids of the Udokan volcanic field located at the boundary of the Aldan Shield and Baikal-Vitim terrane have been studied. Slightly depleted lherzolites are predominant xenoliths in the central part of the field (Pliocene basanites of Lake Kuas), whereas depleted harzburgites prevail in its northern part. The composition of the Udokan peridotites suggests that they are components of the Phanerozoic oceanic mantle subducted beneath the Siberian craton rather than the Archean mantle of the Aldan Shield.
Xenoliths of Lake Kuas are divided into two series: harzburgite-lherzolite and lherzolite-websterite. The latter series probably represents ancient mantle, whereas the former might have been formed through the later interaction of peridotites with a hypothetic silicate melt, which was probably accompanied by Na-amphibole metasomatism. The Kuas spinel harzburgites and dunites are characterized by higher equilibrium temperatures (1000-1050
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