First Results of Dating Detrital Zircons from Late Precambrian Coarse Clastic Sequences of Ulutau Massif, Central Kazakhstan

Resumo

U–Pb geochronological studies of detrital zircons from the Late Precambrian coarse sequence of the Ulutau massif are studied. The concordant ages of detrital zircons from the Satan Fm. composing the lower part of the Ulutau Series are formed by Neoproterozoic (740–888 Ma) and Paleoproterozoic (1989–2600 Ma) populations with the main peaks at 810 and 840 Ma, while less expressed peaks at 2017, 2036, and 2073 Ma. The concordant ages of detrital zircons from the upper part of the studied series, represented by coarse terrigenous rocks of glacial genesis (Baikonur Fm.), are predominantly within the intervals of 650–708, 721–729, and 754–889 Ma with peaks at 674, 721, 763, 772, 791, 821, and 840 Ma. The data obtained indicate that the lower age limit of coarse rocks from the Ulutau Series is about 670 Ma; these rocks formed mainly due to erosion of Neoproterozoic igneous complexes of the basement, which are widespread in the adjacent Maityube zone, with an insignificant role played by older basement rocks of the Ulutau massif.