MARINOAN GLACIATION ON THE SIBERIAN PLATFORM: LA-ICP-MS DATING OF ZIRCON FROM THE TUFF OF THE BOLSHOI PATOM FORMATION IN THE URA UPLIFT
S.V. Rud’ko1, S.V. Malyshev2, M. Ovtcharova3, A.V. Drazdova1, I.V. Fedyukin4, V.B. Khubanov4, A.S. Dubensky1, V.S. Sheshukov1
1Geological Institute of the Russian Academy of Sciences, Moscow, Russia
2Institute of Earth Sciences, Saint-Petersburg, Russia
3University of Geneva, Geneva, Switzerland
4Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences, Moscow, Russia
Keywords: Vendian, Cryogenian, Ediacaran, Middle Siberian glacial horizon, Marinoan glaciation, Siberian Platform
Abstract
LA-ICP-MS dating of zircons from a tuff bed in the Bolshoi Patom Formation in the Ura Uplift yielded an age of 633 ± 7 Ma. The Vendian reference section in the southern Siberian Platform therefore includes the last Cryogenian (Marinoan) glaciation, whereas the postglacial Vendian succession is entirely Ediacaran. Using the obtained age estimate of the Bolshoi Patom Formation, we considered chronostratigraphy of the Riphean-Vendian deposits in the Ura Uplift and in the adjacent areas. The available geochronological and sequence-stratigraphic indicate the presence of a hidden stratigraphic unconformity above the glacial horizon at the base of the Vendian sequence, caused by glacioisostasy.
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