PROBLEMS OF PERFECTING ZONAL STRATIGRAPHIC SCALES

Abstract

Problems of perfecting zonal stratigraphic scales based on the paleontologic evidence are discussed. In all the diversity of biostratigraphic units we operate with, there are two basic types-biostratigraphic zones lacking strict definition of their boundaries and biochronological zones with strictly defined boundaries. Correspondingly, peculiarities of biostratigraphic and biochronological scales and methods of their modernization are considered. When a zone is used as a unit of a section and of a reference scale, the negative consequences are unavoidable. The higher correlation potential of a given scale can be achieved by widening the paleontological characteristic of its zonal units. The chronological continuity of zonal units is determined by the evolutionary succession of fossils used as a basis for the scale elaboration. The correlation accuracy increases when the scale resolution grows. Introduction of non-independent chronological markers into biochronological scales may preserve, but never increases and usually reduces the correlation accuracy. The higher resolution of the biochronological scale can be achieved, provided that its universality and correlation potential are maintained, using the same means that were applied for its elaboration.