Abstract:The late Cretaceous-Cenozoic sediments of fossil soils and weathering crusts of the Baikal rift have been subject to long-term studies. Based on our research results, it is possible to distinguish the following litho-stratigraphic complexes which are related to particular stages of the rift development: the late Cretaceous-early Oligocene (crypto-rift Arheo-baikalian), the late Oligocene-early Pliocene (ecto-rift early orogenic Pra-baikalian), and the late Pliocene-Quaternary (ecto-rift late orogenic Pra-baikalian -Baikalian) complexes. Changes of weathering modes (Cretaceous-quarter), soil formation (Miocene-quarter) and differences of precipitation by vertical and lateral stratigraphy are analysed with regard to specific features of climate, tectonics and facial conditions of sedimentation. Tectonic phases are defined in the Cenozoic period of the Pribaikalie. Аннотация: Подведены итоги многолетних исследований позднемеловых-кайнозойских отложений, палеопочв и кор выветривания Байкальского рифта. Они расчленены на позднемеловой-раннеолигоценовый (крипториф-товый -Археобайкальский), позднеолигоценовый-раннеплиоценовый (экторифтовый раннеорогенный -Пра-байкальский) и позднеплиоценовый-четвертичный (экторифтовый позднеорогенный Палеобайкальский -Бай-кальский) лито-стратиграфические комплексы, связанные с отдельными этапами геологического развития риф-та. Прослежены изменения характера выветривания (мел-квартер), почвообразования (миоцен-квартер) и раз-личия осадков по стратиграфической вертикали и латерали, определяемые особенностями климата, тектоники и фациальных условий осадконакопления. Выявлены тектонические фазы в кайнозое Прибайкалья -Тункинская
ПОЗДНЕМЕЛОВЫЕ-КАЙНОЗОЙСКИЕ ОТЛОЖЕНИЯ БАЙКАЛЬСКОЙ РИФТОВОЙ ВПАДИНЫ В СВЯЗИ
Results of investigations of Baikal bottom sediments from a long core (BDP-97) and several short (0–1 m) cores are presented. It has been shown that the Holocene sediments in the Baikal basins consist of biogenic-terrigenous muds, accumulated under calm sedimentation conditions, and of turbidites, formed during catastrophic events. The turbidites can be distinguished from the host sediments by their enrichment in heavy minerals and thus their high magnetic susceptibility. Often, Pliocene and Pleistocene diatom species observed in the Holocene sediments (mainly in the turbidites) point to redeposition of ancient offshore sediments. Our results indicate that deltas, littoral zones, and continental slopes are the source areas of turbidites. The fact that the turbidites occur far from their sources confirms the existence of high-energy turbidity currents responsible for long-distance lateral-sediment transport to the deep basin planes of the lake.
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