IN SITU U-PB (SHRIMP) DATING OF ZIRCONS FROM GRANOSYENITE OF THE TROITSK PLUTON, KVARKUSH-KAMENNOGORSK ANTICLINORIUM, CENTRAL URALS

Abstract

The Troitsk granosyenite pluton is located among the Neoproterozoic sedimentary sequences of the Kvarkush–Kamennogorsk Anticlinorium on the western slope of the Urals. The sedimentary sequences comprise the Kedrovka and Basegi groups of the Upper Riphean and the Serebryanka and Sylvitsa groups of the Vendian. In the mid-1980s, the Troitsk pluton was used as a reference intrusive body for timing the lower boundary(620 ± 15 Ma) of the Upper Vendian. However, later on, the validity of the Rb–Sr whole-rock isochron age of carbonated granosyenites was questioned. In addition to the Troitsk pluton, a number of other igneous complexes (Shpalorezov, Dvoretsk, Blagodatny, Kus’ya, Zhuravlik, and others) are localized in the Vendian sedimentary rocks of the Kvarkush–Kamennogorsk Anticlinorium. Their petrology, geochemistry, and age are discussed in many publications. The results of geological mapping under the supervision of Suslov made an important contribution to recognition of the geological position of some igneous complexes.