Micropaleontological and Lithogeochemical Characteristics of the Turtas Formation (Upper Oligocene), Western Siberia

— This work presents the results of integrated micropaleontological and lithogeochemical analysis of Upper Oligocene continental deposits of the Turtas Formation from the Zyryanskaya-1 borehole (southwestern part of the Tyumen Region, Western Siberia). The predominance of freshwater planktonic diato...

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Bibliographic Details
Published in:Stratigraphy and geological correlation 2020-05, Vol.28 (3), p.311-329
Main Authors: Oreshkina, T. V., Aleksandrova, G. N., Lyapunov, S. M., Smirnov, P. V., Ermolaev, B. V.
Format: Article
Language:English
Subjects:
Archaeology
Benthos
Boreholes
Climatic conditions
Coastal zone
Diatoms
Earth and Environmental Science
Earth Sciences
Freshwater
Geophysics/Geodesy
Historical Geology
Inland water environment
Lithogeochemistry
Marine microorganisms
Oligocene
Pollen
Sedimentary facies
Sedimentation
Sedimentology
Spores
Structural Geology
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Summary:— This work presents the results of integrated micropaleontological and lithogeochemical analysis of Upper Oligocene continental deposits of the Turtas Formation from the Zyryanskaya-1 borehole (southwestern part of the Tyumen Region, Western Siberia). The predominance of freshwater planktonic diatoms at the subordinate significance of benthic species, as well as the presence of gemmuloscleres of sponges, indicates the coastal sedimentation conditions in a freshwater basin varying in depth from 3 to 50 m. The studied palynocomplex is similar to the spore-and-pollen spectra of the Turtas Formation of the Lower Ob Region, but differs from palynocomplexes of the same formation spread over the southern regions of Western Siberia in a low amount of Taxodiaceae/Cupressaceae and Betulaceae pollen, as well as the absence of Fagaceae pollen and Pseudokomewuia freshwater dinocysts. The revealed differences can be explained both by facies features and by variations in the volume of the Turtas Formation in the currently known localities. The data on the microelemental composition of samples, as well as geochemical and petrogeochemical modules, indicate that the accumulation of the Turtas Formation occurred in the coastal areas of a low-mineralized basin under relatively warm humid climatic conditions.
ISSN:0869-5938
1555-6263
DOI:10.1134/S0869593820030077