First Results of Dating Detrital Zircons from the Late Precambrian Quartzite–Schist Sequences of the Chu Block (Southern Kazakhstan).

U–Pb geochronological studies of detrital zircons from quartzite–schist sequences of the Akbastau Formation of the Chu Block (northwestern part of the Chu–Kendyktas terrane, Southern Kazakhstan) have been provided. The concordant ages of detrital zircons are predominantly within the intervals of 1672–2115 Ma with peaks at 1697, 1780, 1857, and 2066 Ma. Individual zircon grains display ages of 2291–2332 Ma with peaks at 2303 and 2322 Ma. Neoarchean ages of 2608–2747 Ma with a peak at 2681 Ma characterize another significant zircon population. The lower limit of deposition for the Akbastau Formation of the Chu Block, corresponding to the youngest statistically significant zircon population, is estimated at 1.7 Ga. [ABSTRACT FROM AUTHOR]