New data on biostratigraphy of the Vendian Nemakit-Daldynian stage in the southern Siberian platform |
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Authors: | B B Kochnev G A Karlova |
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Institution: | 1.Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Division,Russian Academy of Sciences,Novosibirsk,Russia |
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Abstract: | New paleontological finds in sediments of the Upper Vendian Nemakit-Dadynian Stage from different areas of the southern Siberian
Platforms (Yenisei Range, Sayany region, central areas, Patom Highland) are discussed. The base of the Lower Cambrian Tommotian
Stage (∼540 Ma) is established at the first appearance level of characteristic small-shelled fossils in the western part of
the Patom Highland. This boundary coincides with the episode of a brief sea-level fall and enhanced terrigenous sedimentation
in the basin with dominant carbonate sediment deposition. The base of the Purella antiqua Zone (544 Ma), which is registered by paleontological data in the Yenisei Range sections, is marked by the replacement of
terrigenous sedimentation by the carbonate one. In the northwestern Yenisei Range, this boundary coincides, in addition, with
a major hiatus and subsequent paleobasin extension. The base of the Nemakit-Daldynian Stage (base of the Anabarites trisulcatus Zone, ∼550 Ma) in most sections corresponds to the onset of sea transgression. In addition to small-shelled remains, sediments
of this zone contain characteristic ichnofossils and Vendotaenia flora. It is shown that defined boundaries are traceable through the entire southern part of the Siberian Platform. This
makes them useful for wider stratigraphic interpretations. |
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