U-Pb dating of detrital zircon from the Kokdjot Group and Bolshekaroi Formation (Malyi Karatau) yielded for all the samples age clusters at about 800-805, 855-890, 1980-2100, and 2440-2470 Ma. The Kolmogorov-Smirnov test suggests they have identical provenance sources. The Kokdjot Group and Bolshekaroi Formation ages are presumably Neoproterozoic, not older than 800 Ma, though a somewhat younger age (not older 770 Ma) cannot be ruled out.