LA-MC-ICP-MS zircon U-Pb dating of granite of southwestern Oyu Tolgoi region in South Mongolia and its geological significance

The zircons from biotite granite in southwestern Oyu Tolgoi region show clear oscillatory zoning, indicating that they were formed by normal crystallization of magma. U-Pb dating of 22 zircons was conducted by LA-MC-ICP-MS method. The re-sults show that the data of 21 zircons are clustered around the concordia of 334±2~335±2Ma, yielding a weighted mean ²⁰⁶Pb/²³⁸U age of 335.6±1Ma, which implies that the crystallization of biotite granite in southwestern Oyu Tolgoi region occurred in Early Car-boniferous.