Carbonate Massifs of Talas Sections in Tectonic Setting of the Middle Tien Shan

In the Dzhetym Range, there are well-known Precambrian massifs of marbled limestones and quartzites, which have no analogues throughout the Middle Tien Shan. The authors establish that the quartzite-carbonate stratum occupies the highest structural position in the series of nappes of the region. The U–Pb dating of detrital zircon and zircon from intrusions reliably proves the Riphean age of the quartzite-carbonate stratum, which grounds to compare it with the autochthonous complex of the Karatau–Talas terrane. The autochthonous and parautochthonous units of the Dzhetym Range are composed of Riphean–Vendian sediments of the Middle Tien Shan. The geochemical characteristics and the refined age of the Bolshoi Naryn volcanic-plutonic complex, obtained in the course of this study, indicate that in the Late Riphean this area was a segment of the periocean continental rift, manifested in the time interval of 750–700 Ma ago throughout the entire Tarim–Tien Shan–Kazakhstan region.