THE LATE JURASSIC AGE AND GEOCHEMISTRY OF ULTRAMAFIC-MAFIC MASSIFS OF THE SELENGA-STANOVOY SUPERTERRANE ( southern framing of the North Asian craton )
I.V. Buchkoa, A.A. Sorokin a , E.B. Sal'nikova b , A.B. Kotov b , A.M. Larin b , A.E. Izokh c , S.D. Velikoslavinsky b , S.Z. Yakovleva b
a Institute of Geology and Nature Management, Far Eastern Branch of the RAS, 2 ul. B. Khmel'nitskogo, Blagoveshchensk, 675000, Russia
b Institute of the Precambrian Geology and Geochronology, Russian Academy of Sciences, 2 nab. Makarova, Saint Petersburg,199034, Russia
c Institute of Geology and Mineralogy, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
Keywords: Ultramafic-mafic massifs, framing of the North Asian craton, petrology, geochemistry, isotope dating
Pages: 1026-1036
Abstract
We present new data on the age and geochemistry of the Veselyi and Petropavlovsk ultramafic-mafic massifs of the Selenga-Stanovoy (West Stanovoy) superterrane on the southeastern framing of the North Asian craton. The massifs are composed of rocks of peridotite- websterite-gabbro and peridotite-gabbro-monzodiorite associations, respectively. The latter combine normal, subalkalic, and alkaline rocks and thus are of diverse composition: from ultrabasites and pyroxenites through gabbroids to monzodiorites. The U-Pb zircon age of these massifs is 154±1 and 159±1 Ma, respectively, which permits them to be referred to as the youngest rocks of ultramafic-mafic complexes on the southern framing of the North Asian craton. The rocks of the studied massifs are enriched in LILE (K, Rb, Sr, Ba, LREE) and are depleted in HFSE (Zr, Nb, Hf, Ta). These rocks formed, most likely, in the rear of subduction zone or in the setting of the subducting-slab detachment.
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