About the so-called «Bug series» of the Middle Bug region (Ukrainian shield). Article 1. The evolution of views and the composition of the «Bug series»

Abstract

The name «Bug Series» was introduced into the Precambrian stratigraphic scheme of the Ukrainian Shield more than half a century ago. During this period, ideas about the composition and age of the series changed several times but, until recently, the opinion of various studies about its stratigenic nature remained unchanged. In recent years, many publications have appeared: they express other views on the origin of the «Bug series». Initially, they concerned only individual petrographic groups, such as carbonate and magnetite-bearing rocks, which were attributed to endogenous (magmatic) origin. Later, an opinion about the nonstratigenic origin of the entire «Bug Series» appeared, and some authors proposed to give up on the division of the Early Precambrian granulite complexes into suites. These ideas are only based on the study materials of local objects obtained by drilling and geophysical methods. The author’s conclusions do not take into account the results of regional geological and stratigraphic studies. Simultaneously, with new ideas about the genesis of the «Bug series», an attempt is being made to link its origin with faults and to revise its age. In order to discuss the problem of the «Bug series», a series of publications has been prepared, in which the main generalized data of many years of regional geological and thematic studies on the composition, structure, stratigraphic and structural position of the units belonging to the «Bug series» are presented. The cycle consists of three separate articles. This is the first publication of the cycle, which considers the composition of formations and rock associations that are included in the Bug series in the current stratigraphic scheme of the Precambrian of the Ukrainian Shield. The data presented in this article and its continuations indicate that all these units are most likely of a stratigenic nature. Presumably endogenous formations do not play a significant role in them. According to the author, the name «Bug series» changed its content so often and radically, both in terms of material (rock) and stratigraphic (formation) composition and age, and now also ideas about its genesis, that it has completely lost its stratigraphic certainty and validity. In the modern stratigraphic scheme of the Precambrian of the Ukrainian Shield, the composition and age of the «Bug Series» are also presented in a distorted form. Therefore, in accordance with the provisions of the National Stratigraphic Code of Ukraine and international stratigraphic norms, the name «Bug series» should be abolished, and relevant publications should be discontinued until the adoption of a new stratigraphic scheme for the Precambrian of the Ukrainian Shield. In this new scheme, the stratigraphic division of the granulite complex of the Bug region should be completely revised.