HERCYNIDES OF THE IKAT-BAGDARIN ZONE IN TRANSBAIKALIA

Abstract

The Ikat–Bagdarin zone occupies the internal part of the western Transbaikal region. Granitoids of the Angara–Vitim batholith and metamorphic rocks of unknown age are widespread in this region. Stratified sequences are represented by terrigenous, carbonate, and volcanogenic rocks. This zone is one of the Baikalian–Caledonian terranes accreted in the Early Paleozoic to the southern margin of the Siberian Craton. The age of these sequences is considered Neoproterozoic–Early Paleozoic. The lower Cambrian carbonate sequence with archaeocyaths, trilobites, and brachiopods represents the reference level in this region. At the same time, our work in the Bagdarin area (Bol’shoi Amalat–Tsipikan interfluve) revealed that various Neoproterozoic and Lower Paleozoic formations in this region are supplemented with thick sequences of Middle and, probably, Upper Paleozoic rocks that make up the Hercynian structural stage. This fact changes cardinally the concept of the geological structure of the internal zone of the western Transbaikal region and implies a substantially younger age of its geodynamic evolution.