Upper Ordovician olistostromes of the Agyrek and Kosgombai mountains: Problems of correlation between Lower Paleozoic sedimentary and sedimentary-volcanogenic complexes in central Kazakhstan

The analysis of data on the stratigraphy of Lower Paleozoic sedimentary and sedimentary-volcanogenic sequences in central Kazakhstan made it possible to specify their ages, structural relationships, and correlation with coeval sections of neighboring areas. It is shown that olistostromes widespread in the Agyrek-Arsalan accretionary wedge of the central Kazakhstan Paleozoides are of Katian age. Three stratigraphic units are defined in continuous siliceous sections: Paracordylodus gracilis Beds, Periodon flabellum Beds, and Paroistodus horridus Beds. It is established that Lower Cambrian carbonate-basaltic, Middle-Upper Cambrian carbonate, Upper Cambrian-Lower Ordovician carbonate-terrigenous, and Lower-Middle Ordovician volcanogenic, tuffaceous-siliceous, and siliceous sequences associated with serpentinite melange belong to different lithotectonic zones of Early Paleozoic basins.