Age of Alkaline Rocks Formation in the Area Aryskan Rare-Metal Deposit, Eastern Sayan

Abstract

The age relationships between the alkaline rocks from the region of the rare-metal (Y, REE, Nb, Ta) Aryskan deposit have been determined. Metamict zircon with high content of U, Th was used as a geochronometer. A dedicated treatment protocol was used for sample preparation for geochronological U–Pb (ID TIMS) studies. Dating of zircon from alkaline granites of the Aryskan and nearby Astyg massifs showed that their formation occurred almost simultaneously, 448 ± 1 and 446 ± 1 million years ago, respectively. The supposed genetic relationship of alkaline granites with the accomodating alkaline-feldspar syenites formed 472 ± 2 million years ago (zircon, U–Pb, ID TIMS), has not been confirmed.