Cenozoic sediments from the Selenga-Vitim Downwarp and Baikal Rift Zone spatially combined in the Uro section-Reference-Cited by-同舟云学术

Cenozoic sediments from the Selenga-Vitim Downwarp and Baikal Rift Zone spatially combined in the Uro section

Published:2023-01-07 Issue:6 Volume:22 Page:796-817
ISSN:2500-302X
Container-title:LITHOSPHERE (Russia)
language:
Short-container-title:Lithosphere

Author:

Hassan A. I.¹,Rasskazov S. V.²,Chuvashova I. S.²,Reshetova S. A.³,Rubtsova M. N.⁴,Yasnygina T. A.⁴,Budaev R. Ts.⁵,Al Hamoud A.⁶,Titova L. A.⁷,Rodionova E. V.⁷,Usoltseva M. V.⁷

Affiliation:

1. Institute of the Earthʼs Crust, Siberian Branch of the RAS; Al-Baath University

2. Institute of the Earthʼs Crust, Siberian Branch of the RAS; Irkutsk State University

3. A.P. Vinogradov Institute of Geochemistry, Siberian Branch of the RAS

4. Institute of the Earthʼs Crust, Siberian Branch of the RAS

5. Geological Institute, Siberian Branch of the RAS

6. Al-Furat University

7. Limnological Institute, Siberian Branch of the RAS

Abstract

Research subject. Cenozoic stratified sedimentary formations exposed by well 517 in the Uro area.Aim. To study a section of spatially combined deposits from the Selenga-Vitim Downwarp and Baikal Rift Zone.Methods. Lithological and stratigraphic analysis, lithogeochemical, paleontological studies.Results. Oligocene deposits of the Kularikta Formation from the Selenga-Vitim Downwarp found for the first time, unconformably overlain by deposits of the Baikal-type basins of the Baikal Rift Zone (Miocene-Lower Pliocene Tankhoi Formation, Upper Pliocene-Eopleistocene Anosov Formation, and Quaternary polyfacies stratum). Four palynocomplexes are characteristic of the section: PC I of the Early Oligocene shows mixed forests of spruce, pine, hemlock with an admixture of alder, birch, and broad-leaved deciduous trees with an insignificant participation of evergreens that existed in a warm temperate climate; PC II of the Late Oligocene reflects expansion of areas of coniferous vegetation in the transition to a moderate climate; PC III of the Early Miocene demonstrates mesophilic coniferous forests and a significant role of broad-leaved tree species in warmer and more humid climatic conditions; PC IV of the Late Miocene–Early Pliocene displays vegetation close to taiga with rare relics of coniferous and deciduous plants under conditions of increasing cooling with a decrease in total moisture supply. A lack of pollen grains in the transitional deposits from the Kularikta to the Tankhoi Formation of the late Oligocene–early Miocene corresponds to conditions of a paleoclimatic pessimum. A member of lacustrine sediments with diatoms was found in the Tankhoi Formation, 50 species of diatoms are identified, among which the planktonic species Alveolophora antiqua is absolutely dominant in a paleowater body of significant depths and a large volume of water mass.Conclusion. The Uro section combines the Oligocene deposits of the Selenga-Vitim Downwarp and Miocene-Quaternary deposits of the Baikal Rift Zone.

Publisher

IGG UB RAS

Subject

Stratigraphy,Geochemistry and Petrology,Geology,Geophysics

Reference54 articles.

1. Akhmet’ev M.A. (1993) Phytostratigraphy of Paleogene and Miocene continental deposits of Extratropical Asia. Moscow, Nauka Publ., 144 p. (In Russ.)

2. Akhmet’ev M.A., Volobueva V.I., Gladenkov Yu.B., Sheludchenko S.D. (1981) Late Paleogene cooling in the East of the USSR according to paleobotanical data. Bull. MOIP. Otd. Geol., 4, 87-100. (In Russ.)

3. Al Khamud A., Rasskazov S.V., Chuvashova I.S., Tre gub T.F., Volkov M.A., Kulagina N.V., Kolomiets V.L., Budaev R.T. (2019) Temporal Compositional Variations of Cenozoic Sediments on the Tankhoi Tectonic Step, the Southern Baikal. Bull. Irkutsk Gos. Univ. Ser. Nauki o Zemle, 30, 108-129. (In Russ.) https://doi. org/10.26516/2073-3402.2019.30.108

4. Al Khamud A., Rasskazov S.V., Chuvashova I.S., Tregub T.F., Rubtsova M.N., Kolomiets V.L., Budaev R.Ts., Khassan A., Volkov М.А. (2021) Overturned Eocene – Lower Pliocene alluvial stratum on the southern coast of Lake Baikal and its neotectonic significance. Geodynam. Tectonophys., 12(1), 139-156. (In Russ.) https://doi. org/10.5800/GT-2021-12-1-0518

5. Baranova Yu.P., Biske S.F. (1979) Paleoclimates of the Paleogene and Neogene of Northeast Asia. Continental Tertiary strata of Northeast Asia. Novosibirsk, Nauka Publ., 186-204. (In Russ.)