Revisiting stratigraphic complexes and regional stratigraphic scheme of the lower precambrian of the Ukrainian shield. Article 2. Correlation of complexes of ukrainian and other shields of North Eurasia

Abstract

The second article discusses the 5 main types of stratogenic metamorphic complexes found in the East-European and Siberian platforms: 1) granulite-gneissic; 2) amphibolite-gneissic; 3) greenstone; 4) ferruginous-siliceous-schistose (metavolcano-chemo-terrigenic) 5) gneiss-schistose (metacarbonaceous-terrigenic). The types of complexes, in addition to the fact that they differ in the degree and type of metamorphism, also have different geologic-formational composition. These complexes are seen as the largest regional stratigraphic subdivisions in all regions of the Early Precambrian. They are represented with varying degrees of completeness on the Aldan-Stanovian, Anabarian and Baltic shields and on the Voronezh crystalline massif. The most complete stratigenic metamorphic complexes are developed on the Ukrainian and Aldan-Stanovian Shields. The complexes of the various regeions are mutually correllated between themselves and the Ukrainian Shield based on them corresponding to the types of stratogenic metamorphic complexes. The similarities between the complexes across different regions are to most researchers evidence not only of similar conditions of the formation of same-type complexes, but also, most likely, their conformance to identical quasi-synchronous stages in the development of the Earth’s core. Based on the results of both articles of the cycle, it is concluded that the largest divisions of the current Chronostratigraphic Scheme of the Early Precambrian of the Ukrainian Shield, which are shown in it as “series”, deserve either the transfer to the rank of “stratigraphic complexes” or the inclusion in the complexes by uniting series. Combining of the series concern to granulite-gneiss complexes that need to be renamed in the updated stratigraphic scheme. For other complexes, for the sake of inheritance with the previous schemes, it is advisable to preserve the geographical names of the series.