The First Results of U—Pb Dating of Zircons from Gneissic Granites of the Kharbei Complex (Polar Urals)

摘要

Data on the age of gneissic granites from the Precambrian Kharbei Complex (Polar Urals) have been obtained for the first time. Local U—Pb dating was carried out using a SHRIMP-II ion microprobe. Zircons were taken from three granitic bodies close in petrographic and petrochemical parameters. The formation of gneissic granites was implemented in two stages: during the Late Ediacarian (556 ±2.2 Ma) and in the Late Cambrian (497 ± 3 and 487.1 ± 2.1 Ma). The rocks formed owing to rheomorphic flow of granitic material, caused by tectonic events related to Timanian (Baikalian) tectogenesis and epicontinental riftogenesis, which occurred prior to the appearance of the Paleouralian Ocean.