The oldest island-arc granitoids of Chingiz-Tarbagatay region (Eastern Kazakhstan): age substantiation and сomposition affinities

The oldest granitoids of Kan-Сhingiz complex in Chingiz-Tarbagatay region of Eastern Kazakhstan, composed of quartz diorites, granodiorites, plagiogranites and granites, are first dated. U-Pb (ID-TIMS and SIMS) geochronological study of granites and plagiogranites is carried out and age estimates 509±2 and 512±3 Ma, approximately corresponding to the boundary of Early and Middle Cambrian, are obtained. These data allow to consider the age of volcanic-sedimentary sequences, host for granitoids, as Early Cambrian. Composition affinities of granitoids of Kan-chingiz complex indicate their formation within ensimatic island arc.