AMMONITE BIOSTRATIGRAPHY AND BIOGEOGRAPHIC CLASSIFICATION OF THE WEST SIBERIAN BASIN IN THE KIMMERIDGIAN
S.V. Meledina
Institute of Petroleum Geology, Siberian Branch of the RAS,
3 prosp. Akad. Koptyuga, Novosibirsk, 630090
Keywords: Biostratigraphy, ammonites, Kimmeridgian, biogeographic realm, province, subprovince, West Siberia
Pages: 989-1002
Abstract
Support is given to the division of the Lower Kimmeridgian into the Pictonia involuta and Rasenia evoluta Zones adopted for West Siberia. It is shown that the Upper Kimmeridgian is recognizable in boreholes, still without zonation. Specific taxonomic differentiation of the Kimmeridgian families and genera of ammonites in the Northern Hemisphere permits recognition of two zoogeographic realms, circumpolar Arctic and Boreal-Atlantic, which taken together form the Panboreal Superrealm. A wide ecotone existed between them, treated as the Greenlandian-Uralian Province. In the Early Kimmeridgian, this province was part of the Arctic Realm, whereas in the Late Kimmeridgian it belonged to the Boreal-Atlantic Realm. The province is subdivided into subprovinces: nominal North Siberian and two West Siberian, western and eastern.
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