New data on the age of granites of the Kodar and Tukuringra complexes, eastern Siberia: Geodynamic constraints

U-Pb zircon dating of the Kemen and Khani granite massifs from the Kodar Co mplex of the western Aldan Shield yielded ages of 1876.5 +/- 4.2 Ma and 187 3.1 +/- 2.5 Ma, respectively. These results indicate a considerably older a ge for the granites of the Kodar Complex than was previously suggested (Rub lev et al., 1981, 1987) and allow us to distinguish an additional episode o f the Early Proterozoic granitoid magmatism (1.87-1.88 Ga) in the evolution of the Aldan Shield. This episode marks presumably the final stage of coll ision between the Aldan and Dzhugdzhur-Stanovoi microcontinents. The granit es of the Getkan Massif of the Tukuringra (late Stanovoi) Complex (Dzhugdzh ur-Stanovoi folded system), which was traditionally considered as an age co unterpart of the Kodar Complex, were dated by the U-Pb method at 142.1 +/- 1.8 Ma. These granitoids were presumably formed during the collision of the Khingan and Amur microplates with the Siberian continent.