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A. A. Shchetnikov I. A. Filinov I. V. Shibanova I. M. Mashchuk A. V. Sizov 《Stratigraphy and Geological Correlation》2009,17(4):454-459
The biostratigraphic study of a new Upper Cenozoic reference section in the Tunka rift valley (southwestern Baikal region) accompanied by radiocarbon measurements made it possible to date its lithological units. It is established that the section is largely composed of Upper Pleistocene fluvial sediments resting with distinct angular unconformity uapon Pliocene conglomerates. The revealed structural features of the section confirm the views that the directed development of the Tunka depressions was complicated by local inversions, when the sedimentation area became reduced. The main sedimentation features during the Late Cenozoic and its stages are reconstructed for the studied area. 相似文献
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Devonian and Lower Carboniferous continental deposits in the south of the Siberian Platform formed in eight sedimentary basins localized within stable ancient land Angarida (Angaraland). Interbasin correlation of the stratigraphic units of these deposits was based mainly on analysis of paleontological data and marker horizons. It has been established that: (1) the Early and Middle Devonian flora of Angarida grew locally and only in its western part (Minusa and Rybinsk paleobasins); (2) in the Late Devonian, vegetation was dispersed over a vast area, as evidenced from the findings of its imprints in all existed sedimentary basins of continental lithogenesis; and (3) the Early Carboniferous in Angarida was the time of the flourishing of higher plants, which were abundant but poor in species. Lithologic benchmarks at different age levels of paleobasin sediments have been recognized. The most important marker horizons are composed of porcelain-like silicified tuffs, limestones with inclusions of brown chalcedony, calcilutites, salt rock, wax-like bentonitic mudstones, flint clays, tripolis, etc. 相似文献
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New data are reported on the stratigraphy of the Oligocene deposits of Lake Baikal (the Tankhoi field, the outcrops near the mouths of the Osinovka, Polovinka, and Klyuevka Rivers). Detailed paleontological analysis of the key sections on the continental part of the Baikal eastern coast revealed four floristic horizons that could be used as indicator horizons and showed that the Tankhoi Formation formed throughout the Oligocene and at the early Early Miocene. Lithologically, blue vivianite clays and coal beds could be used as the most important indicator horizons. Formation of the deposits began after a long stratigraphic break from the Early Cretaceous to the Early Oligocene. The deposits were formed by erosion and denudation of weathering crust and accumulation of redeposited weathering residues in the Tankhoi paleobasin with a lacustrine-marsh landscape. Coarse-clastic foehn deposits of the Osinovka Formation, containing rich Miocene palynological assemblages, were eroded and overlie concordantly the Upper Tankhoi Subformation and redeposited weathering residues of the weathering crust, and underlie the Anosovka Formation. The study suggests that the Baikal rift valley began to form at 38 Ma. 相似文献
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