Recent studies allow refinement of the principal Vendian stratigraphie standard of the Russian platform. The Vendian, which was established 20 years ago as the youngest sedimentary complex of the upper Precambrian of the Russian platform, is significant in correlation of upper Precambrian rocks on a wide scale. Peculiar geologic features of the Vendian, its structural and stratigraphie position, and its strati-graphic boundaries and subdivisions are in many respects comparable with upper Precambrian rocks of other regions and continents. The Vendian is also significant in determination of the position of a main glacial formation, in recording the earliest appearance of an Ediacaran-type fauna and in the relation of this fauna with a paleontologie succession of the oldest Precambrian, and in isotopic-age characteristics. All these features are of more universal importance than are facies characteristics of the formations composing the Vendian (and its equivalents); thus, the Vendian of the Russian platform has rapidly become a most significant time-stratigraphicstandard.
Although the Vendian is represented by terrigenous deposits on the Russian platform and by carbonate and carbonate-terrigenous deposits on the Siberian platform, it undoubtedly represents an important, separate stage in the geologic history of the earth. At the transition from the Vendian to the Cambrian, an important biologic change took place which resulted in the appearance of skeletal-building properties of organic parts of animals. The significance of such a succession is worldwide. It is concluded that the Vendian represents the beginning of the Phanerozoic—not the close of the Cryptozoic—and is more closely related to the Paleozoic, though formally it is not included in that era.
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Following the discovery of Prudhoe Bay oil field in 1968, much attention was turned to the Arctic in the search for giant hydrocarbon accumulations. The Soviets had already proved giant reserves in their West Siberian Basin, and exploration was moving ahead quickly in the Canadian Arctic. Plans were drawn up for an AAPG Symposium on Arctic Geology and held in February 1971. Papers were selected from the Symposium for this publication and cover seven topical groupings: Regional Arctic Geology of Canada, Regional Arctic Geology of the Nordic Countries, Regional Arctic Geology of the USSR, Regional Arctic Geology of Alaska, Comparisons in the North Atlantic Borders, Evolution of the Arctic Ocean Basin, and Economics of Petroleum Exploration and Production in the Arctic.