Biostratigraphy of the Devonian–Lower Carboniferous Deposits of the Bambuysko–Olingda Subzone (South Muya Ridge, Western Transbaikalia)

The results of biostratigraphic studies of the Devonian–Lower Carboniferous deposits of the Bambuysko–Olingda Subzone of the Vitimkan–Tsipa Zone of the Baikal–Vitim fold system are presented. These deposits are isolated from the composition of the Riphean and Vendian–Cambrian formations. Their age was revised on the basis of numerous findings of fossil fauna and flora. The Bambuiskaya carbonate and Chulegminskaya terrigenous suites and the Kadala terrigenous-carbonate stratum are assigned to the Devonian. The Uendect volcanogenic-terrigenous sequence is dated as Late Devonian (Famennian)–Early Carboniferous (Tournaisian), while the terrigenous Ognenskaya and Amatkan suites are dated as Early Carboniferous (Tournaisian and Visean), respectively. Significant changes have been made to the Paleozoic stratigraphic scheme of the subzone. Paleolandscape reconstructions for the Bambuysko–Olingda basin and coastal land areas in the Devonian–Early Carboniferous are proposed. The Devonian carbonate complex was formed under calm conditions of a shallow warm shelf sea. A change in the paleolandscape environment occurred at the Devonian–Carboniferous boundary. The accumulation of thick strata continued under the conditions of a deepening open shelf-slope paleobasin adjacent to the volcanic zone.