THE AGE AND GEOCHEMISTRY OF VOLCANIC ROCKS ON THE EASTERN FLANK OF THE UMLEKAN-OGODZHA VOLCANOPLUTONIC BELT ( Amur region )
A.A. Sorokina, A.P. Sorokina, V.A. Ponomarchukb, and A.V. Travinb
a Institute of Geology and Natural Management, Far Eastern Branch of the Russian Academy of Sciences, 1 per. Relochnyi, Blagoveshchensk, 675000, Russia
b V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
Keywords: Isotope dating, 40Ar/39Ar method, andesites, geochemistry, geodynamics, East Asia, Umlekan-Ogodzha belt, Khingan-Okhotsk belt
Pages: 369-379
Abstract
40Ar/39Ar dating yielded the reliable ages of andesite from the Unerikan complex (102.1 ± 1.4 Ma) and basaltic andesite from the Burunda complex (107.3 ± 2.4 Ma). The established age of volcanism is close to one of the stages of formation of the Khingan-Okhotsk volcanoplutonic belt. The petrography and geochemistry of basic, normal-basic, and normal rocks point to their dual character: They combine features specific for tholeiitic and calc-alkalic rocks. Most likely, these rocks formed in the setting of transform continental margin.
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