Evolution of the northeastern margin of the Kazakhstan paleocontinent: results of petro-geochemical study of sedimentary and volcanogenic-sedimentary rocks of the Zharma-Saur island arc zone

We carried out studies of petrography, petrochemistry, geochemistry and Nd-isotopy of sedimentary and volcanic rocks, as well as U‒Pb dating of detrital zircons from sandstones and tuff sandstones of four stratigraphic units of the Zharma-Saur island arc zone, located in the Middle-Late Paleozoic near the north eastern (in modern coordinates) edge of the Kazakhstan paleocontinent. The data obtained, geological structure and analysis of discriminant diagrams indicate that the formation of sandstones of the Givetian‒Frasnian sequence was the result of erosion and destruction of the Early Paleozoic igneous complexes of the Chingiz-Tarbagatai zone of the Kazakhstan paleocontinent. Tuff sandstones of the Koyanda formation of the Tournaisian stage and the Tersairyk formation of the Visean stage, distributed within the Vorontsov-Saur subzone, are mainly a product of rock destruction and volcanic activity of the Zharma-Saur volcanic arc. The feeding provinces for the sedimentary rocks of the Kokon formation of the Visean stage, which occupies most of the Zharma-Sarsazan subzone, were simultaneously the Caledonides of the Chingiz-Tarbagatai zone and the Early Carboniferous volcanogenic complexes of the Zharma-Saur volcanic arc. Our data show that the Zharma-Saur arc developed near the northeastern margin of the Kazakhstan paleocontinent at the end of the Late Devonian‒in the Early Carboniferous period.