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Russian Geology and Geophysics

2004 year, number 3

GEOCHEMISTRY OF PALEOZOIC GRANITOID MAGMATISM IN THE WEST STANOVOY ZONE OF TRANSBAIKALIA

M.E. Kazimirovsky
Institute of Geochemistry, Siberian Branch of the RAS, 1a ul. Favorskogo, Irkutsk, 664033, Russia
Keywords: Petrochemical characteristics, granitoid complexes, geodynamic settings, Paleozoic, Transbaikalia
Pages: 325-340

Abstract

Detailed petrochemical characteristics of Paleozoic (Cambrian(?)-Silurian and Carboniferous) granitoids of the West Stanovoy structure-formational zone (SFZ) (central Selenga-Stanovoy mountain area (SSMA), Transbaikalia) are presented. The Early Paleozoic granitoids of the Krestovsky and Olekma igneous complexes are shown to be similar in evolution and lithology in both N-S and W-E strikes, which hampers distinction between them. A Carboniferous granite-leucogranite intrusive complex is recognized in the study region, which is consistent with the magmatic history of the adjacent Khilok-Vitim SFZ. In accordance with the known lithological criteria for paleogeodynamic interpretation of granitoids, the Early Paleozoic igneous formations of the West Stanovoy SFZ have all features of palingenic batholiths of active continental margins (ACM), which is confirmed by modern paleogeodynamic reconstructions of the region. Carboniferous granitoids might have formed either during the development of a "transform" margin at the shifts of the Yablonovy terrane along the ACM of the Paleo-Siberian continent or under the effect of within-plate mantle plume, which gave rise to the Angara-Vitim batholith. The results obtained are of paramount importance for petrochemical identification of Paleozoic SSMA granitoids and for solving the problems of the pre-Mesozoic geodynamics of the Mongolo-Okhotsk belt and Central Asian paleo-ocean as a whole.