Concerning the discussion about the Bug series of the Middle Bug (Ukrainian shield)

Abstract

The materials of several articles and reports published in 2022 by the authors of this work and V.P. Kirilyuk (Kirilyuk, 2022 a,b), who discussed the structure and stratigraphy of the Вug area granulite complex of the Ukrainian Shield. The authors, relying on their geological, geophysical and geochemical studies, isotopic geochronology data, as well as on the world experience in studying the Early Precambrian complexes of the Canadian and Australian shields, argue that during 3.8—1.7 Ga, the Bug area granulite complex underwent at least a threefold structural metamorphic processing. Its modern structural plan, as well as, to a large extent, the composition and structural and textural features of metamorphic rocks, are of Early Proterozoic age. Therefore, its division into suites of primary sedimentary-volcanogenic rocks and their vertical distribution by age does not make sense. Only a division into two series is possible — the Dniester-Bug and the Bug, between which there is a tectonic contact. Contrary to this, V.P. Kirilyuk, relying on the experience of his stratigenic-metamorphogenic studies and the authority of the well-known school of L.I. Salopa, E.M. Lazko et al., defends the point of view on the stratigenic nature of the Bug area granulite complex, in which the primacy and stability of the position of strata-formations relative to each other were preserved throughout the entire time. According to V.P. Kirilyuk, there are no breaks and disagreements between the suites, so he proposes to abandon the identification of the early Precambrian USh Bug Group. And the seven suites identified by him, the youngest of which is 3.8 billion years old, are proposed to be attributed to a single Dniester-Bug series. The authors of both alternative points of view apply to the National Stratigraphic Committee of Ukraine with a proposal to revise the stratigraphic scheme of the Early Precambrian of the USh.