Abstract

One of the major problems of Devonian biostratigraphy in the Asiatic part of the USSR is the imprecise definition of some local unit boundaries. The conventional correlation of these Asiatic units with those of the Ardenno-Rhenish stratigraphic scale is discussed. Because of the variety of earlier methods for defining biostragraphic units controversy still exists among Soviet stratigraphers. Suggested solutions of these problems are discussed. One approach is to establish an inter-regional stratigraphic scale incorporating local units up to the rank of series, based on data available for southern West Siberia and the South Tien Shan. This scale is based on evolutionary stages of organisms, an approach commonly used for solution of biostratigraphic problems. The main emphasis in this paper is on a “division” (stage). This scale is not proposed as an alternative to a Standard scale established by the Subcommission on Devonian Stratigraphy, but is directed primarily to discrimination of “boundaries” for precise global correlations. Each scale supplements the other.