Early proterozoic terranes, collision zones, and associated anorthosites in the northeast of the Siberian craton: Isotope geochemistry and age characteristics

Specific features and evolution of tectonic elements of the ancient contine ntal crust in the northeast of the Siberian craton are discussed on the bas is of isotope-geochronological materials. We used data on the exposed basem ent within the Anabar Shield and Olenek uplift and results of studies of co re from deep boreholes and crustal xenoliths in kimberlite pipes together w ith interpretation of geophysical fields where the basement is overlain by the Riphean-Phanerozoic sedimentary cover. New and earlier Sm-Nd dates are discussed, as well as the results of dating by the U-Pb zircon method, incl uding dating of single grains on a SHRIMP mass spectrometer. The Siberian craton in its northeastern part formed in the Late Paleo-Prote rozoic (2.0-1.8 Ga ago) as a result of accretion of Archean microcontinents - granulite-gneiss and granite-greenstone terranes associated along collis ion fault zones. The juvenile substance of granulite-gneiss terranes (Magan and Daldyn) were separated from the exhausted mantle 3.1 Ga ago, whereas t hat of granite-greenstone terranes (Birekte and Markha) 2.5-2.4 Ga ago. Pri mary volcanosedimentary complexes that developed on their basement formed 2 .4 Ga ago (Vyurbyur series of granulites of the Magan terrane) and 2.1 Ga a go (Khapchan granulite and Aekit greenschist fold belts of the Birekte terr ane).