NEW DATA ON ALBIAN BIOSTRATI GRAPHY OF THE NORTHERN PALEOBIOGEOGRAPHIC REGION OF WEST SIBERIA (FROM FORAMINIFERA)

V. M. Podobina

Tomsk State University, Tomsk, Russia

New cross-sections of the Khanty-Mansi horizon within the Northern paleobiogeographic region of West Siberia have been studied. The author updated data on biostratigraphy of the region based on foraminifera findings from four well columns at the Yuzhno-Russkaya area. The systematically more diverse Middle and Late Albian foraminifera assemblages have earlier been studied from 10 well columns at the Samotlorskaya area (latitudinal Ob River stream). Unlike those from the Samotlorskaya area, foraminifera assemblages from the Yuzhno-Russkaya area characteristics of three Albian substages. Almost all Albian assemblages identified in the Northern region correspond to a certain extent to those have uggested for Trans-Urals ones. The Lower Albian is characterised by Gaudryinopsis toilleuri assemblages, the Middle Albian – by Ammobaculites fragmentarius, Gaudryinopsis filiformis assemblages, the Upper Albian – by Ammotium brunsteini, Verneuilinoides borealis assanoviensis major assemblage, and the uppermost Upper Albian – by the Miliammina ischnia assemblage. Many types of foraminifera assemblages in the Northern region are somewhat similar to those ones in Trans-Urals and North Alaska. However, shells of foraminifera in the Northern region are characterized by more coarse-grained walls and poorer preservation. The Albian age of West-Siberian stratons was refined due to findings of common and vicarious species as well as geographic sub-species among assemblages of the West-Siberian and Canadian provinces (Western Canada, Northern Alaska). In general, the Albian age of the Khanty-Mansi horizon and all its subdivisions was confirmed.

Keywords: foraminifera, Khanty-Mansi horizon, Albian, West Siberia.

DOI 10.20403/2078-0575-2017-4-3-10

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