| Реферат: | eng: Newly obtained U-Pb and Sm-Nd isotopic data on Early Precambrian metamorphic and granitoid complexes in the southwestern margin of the Siberian craton (Sharyzhalgai basement uplift) are synthe-sized in order to elucidate the crustal evolution starting at the Paleoarchean (~3.6 Ga) to Late Paleoproterozoic (~1.85 Ga), evaluate the lateral extent of the Paleo-Mesoarchean crust, and identify major stages in its growth and recycling. Two crustal growth stages were determined in the Onot and Bulun granite-greenstone terranes: at 3.6-3.3 and 2.8-2.9 Ga. The earliest recycling processes (at ~3.4 and 3.2 Ga) involved partial melting, metamorphism, and migmatization and produced a stable continental crust. Crustal growth in the Mesoarchean (~2.8-2.9 Ga) due to basaltoid magmatism was associated with the recycling of the Paleoarchean crust, which served as a source of felsic melts and of detrital material for terrigenous sediments. The Archean crust of the Irkut granulite-gneiss terrane was formed by two pulses of intermediate-felsic and basic volcanism at ~3.6-3.4 and ~2.7 Ga. In the terminal Archean (at ~2.55 Ga), the preexisting crust was involved in metamorphic and magmatic processes. Traces of recycling of the Paleoproterozoic crust are identified in the isotopic parameters of the intermediate-felsic granulites. Two discrete stages in the influx of juvenile material are identified in the Paleoarchean: at ~2.0 and 1.88-1.85 Ga, with the latter stage associated with the large-scale recycling of the Archean crust during the origin of granitoids. © Pleiades Publishing, Ltd., 2010.
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