The U–Pb Age of Zircons and Metamorphism of Rocks in the Vishnevogorsky Sequence (Southern Urals)

Abstract

The results of U–Pb zircon dating, as well as the petrologic-geochemical study of samples of zircon-bearing garnet–biotite plagiogneiss and quartz—plagioclase–amphibole granofels from the Vishnevogorsky sequence of the oldest rocks of the Eastern domain of the Southern Ural are presented. The zircon ages were obtained using an ion microprobe (SHRIMP II). The maximum age of the substrate of plagiogneises in the Vishnevogorsky sequence is not younger than 2700 Ma and the granulite metamorphism of plagiogneiss falls in the Proterozoic age range of 1740–2220 Ma. The dates obtained for plagiogneisses and granofels of the Vishnevogorsky sequence reflect all major (PR1–P1) age stages in the development of the Urals. Many of the dated events have manifested only in the zircon generations and are not reflected in the mineral parageneses of the studied rocks.