The ages of the two main stages of carbonate cover formation within the Tuva-Mongolian microcontinent have been determined. The Pb-Pb age and Sr-chemostratigraphic characteristics of the carbonate rocks of the Irkutnaya, Agaringol, and Zabita formations, as well as of the Zabita Formation phosphorite, demonstrate that the first stage began in the Middle Riphean (Late Ectasian) at about 1290 Ma and the second stage started in the Early Vendian (Early Ediacaran) at 630-600 Ma. The accumulation of phosphorite deposits started in the Ediacaran at about 580 Ma.