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Foraminifera and Late Cenomanian-Turonian biostratigraphy of the northern palaeobiogeographic district of Western Siberia Cover

Foraminifera and Late Cenomanian-Turonian biostratigraphy of the northern palaeobiogeographic district of Western Siberia

By: Vera Podobina  
Open Access
|Oct 2013

Abstract

The study of 114 core samples from seven borehole sections of the Van-Eganskaya area in the central part of Western Siberia yielded sufficient data to investigate the Late Cenomanian-Turonian foraminifers, palaeoenvironments, and the Late Cenomanian-Turonian biostratigraphy of this poorly studied area. Two Late Cenomanian foraminifer zones were established, viz. a (lower) Saccammina micra - Ammomarginulina sibirica Zone and an (upper) Trochammina wetteri tumida - Verneuilinoides kansasensis Zone. They reflect changes in the species composition of the foraminifer assemblages and lithology of the host rocks of the Uvatskian Horizon. In the lower part of the upper zone, beds with Gaudryinopsis nanushukensis elongatus are present. The changes in the species composition and lithology of the upper Cenomanian resulted from water-depth variations during the Boreal transgression. Two distinct assemblages and two homonymous zones, viz. the (lower) Gaudryinopsis angustus and the (upper) Pseudoclavulina hastata zones occur in the Turonian clayey cap-rocks of the superimposed Kuznetsovskian Horizon. Comparison of the Late Cenomanian-Turonian assemblages from the West-Siberian and Canadian provinces of the same Arctic palaeobiogeographical realm shows that the West-Siberian species are the same as, and closely related to, Canadian taxa, along with geographical subspecies. This comparison allows a detailed correlation, which results in a precise dating of the foraminifer zones.

DOI: https://doi.org/10.2478/logos-2013-0013 | Journal eISSN: 2080-6574 | Journal ISSN: 1426-8981
Language: English
Page range: 201 - 227
Published on: Oct 8, 2013
Published by: Adam Mickiewicz University
In partnership with: Paradigm Publishing Services
Publication frequency: 3 issues per year

© 2013 Vera Podobina, published by Adam Mickiewicz University
This work is licensed under the Creative Commons License.