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Russian Geology and Geophysics

2007 year, number 1

SIGNATURE OF PRECAMBRIAN EXTENSION EVENTS IN THE SOUTHERN SIBERIAN CRATON

D.P. Gladkochub a , T.V. Donskaya a , A.M. Mazukabzov a , A.M. Stanevicha, E.V. Sklyarov a , and V.A. Ponomarchuk b
a Institute of the Earth's Crust, Siberian Branch of the RAS, 128 ul. Lermontova, Irkutsk, 664033, Russia
b Institute of Geology and Mineralogy, Siberian Branch of the RAS, 3 prosp. Koptyuga, Novosibirsk, 630090, Russia
Keywords: Dike swarm, rifting, passive margin, Precambrian, supercontinent, Rodinia, Siberian craton, Paleoasian Ocean
Pages: 17-31

Abstract

We investigate extension events in the southern Siberian craton between 1.8 and 0.7 Ga. Signature of Late Paleoproterozoic within-plate extension in the Northern Baikal region is found in 1674 ± 29 Ma dike swarms. A Mesoproterozoic extension event was associated with intrusion of the 1535 ± 14 Ma Chernaya Zima granitoids into the Urik-Iya graben deposits. Neoproterozoic extension recorded in the Sayan-Baikal dike belt (740-780 Ma dike complexes) was concurrent with the breakup of the Rodinia supercontinent and the initiation of the Paleoasian passive margin along the southern edge of the Siberian craton. The scale of rifting-related magmatism and the features of the coeval sedimentary complexes in the southern Siberian craton indicate that Late Paleoproterozoic and Early Mesoproterozoic extension did not cause ocean opening, and the Paleoasian Ocean opened as a result of Neoproterozoic rifting.