Late Ordovician and Silurian Supra-Subduction Complexes of the Karakamys Block of Southwestern Kazakhstan

The Late Ordovician and Silurian ages, previously considered as the Precambrian, were established for the first time for plutonic and volcanic complexes of the Karakamys block of Southwestern Kazakhstan. U–Pb (SIMS, and ID-TIMS) geochronological study of gneiss–granites and felsic volcanic rocks was carried out, and age estimates of 443 ± 5 Ma and 436 ± 2 Ma, consequently, were obtained. These data allow us to refer gneiss–granites to the very end of the Ordovician and the beginning of the Silurian, and felsic volcanic rocks and tuffs, to the Llandovery series of the Silurian. Special features of the composition of granitoids and felsic volcanic rocks indicate their formation in supra-subduction settings.