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NEW DATA ON BIOSTRATIGRAPHY AND FORAMINIFERA OF THE APTIAN STAGE OF WEST SIBERIA

V. M. Podobina

National Research Tomsk State University, Tomsk, Russia

New complexes of Aptian foraminifera have been studied from two well sections (the Yamal Peninsula) in the northern paleobiogeographic region of West Siberia. These complexes are confined to the Vikulovo Horizon, where three Aptian substages are identified in the section of A well, the second section of B well are characterized by less and insufficiently preserved foraminifera, therefore, the Aptian age of deposits inclosing these organisms has been established as a whole. The new species – the index Gaudryinopsis sibiricus Podobina sp. nov. has been identified in the first section of A well within the lower substage together with the second species known here, which previously became the index species Trochammina reinwateri Cushman et Applin. In the middle substage, previously known species - indices Ammomarginulina obscura (Loeblich) and Pseudoverneuilina aptica Podobina have been traced. The upper substage in the section of A well is determined only by representatives of two generic taxa – Ammomarginulina and Trochammina. The deposits of the lower substage of the Aptian characterized by this complex of foraminifera define its boundary with Lower Cretaceous stages.

Keywords: foraminifera, Aptian, new sections, northern paleobiogeographical region, West Siberian province.

DOI 10.20403/2078-0575-2024-3-3-9

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