The Late Vendian Basement within the Limits of the Blyb Metamorphic Complex, Peredovoi Range of the Greater Caucasus

Abstract

New data are presented concerning the age and relationships with the overlapping rocks of the Balkan massif of quartz diorites located in the central part of the Blyb metamorphic complex of the Peredovoi Range of the Greater Caucasus in the Malaya Laba River basin. For the first time, using modern geochronological methods, it is shown that the Balkan massif is a Precambrian formation. An estimate of the age of the rocks of the Balkan massif using the SHRIMP II method for three U–Pb datings gives an interval of 549 ± 7.4 to 574.1 ± 6.7 Ma. A new interpretation of the structure of the basement of the Peredovoi Range is suggested, according to which the rocks of the Late Vendian foundation are exposed in a tectonic window and overlapped by Middle Paleozoic metamorphic rocks of the Armov cover, first identified by a combination of geological features. The lower boundary of the cover is characterized by a sharp change in composition and a change in the orientation of planar textures. On the border with the Armovka cover, there is a thick blastomilonite unit.