The Characteristics and Age of Zircon in Lujing Kimberlite-like Rock (Kimberlitic Lamprophyre) in Southern Jiangxi and Its Tectonic Significance

The Nanling area is famous for its widely distributed granites, however, there are also many mafic to ultra-mafic intrusion, Lujing kimberlite-like rock (kimberlitic lamprophyre), located in Caifang Town, Anyuan Country of South Jiangxi province, being one of these intrusions. Based on a field survey, we investigated the rock formation time of Lujing by SHRIMP zircon U-Pb dating, and determined its age as 132.0 Ma (range in 128.7-135.4 Ma). Meanwhile, early xenocryst of 1945 Ma old was found, which indicates that there is a Palaeoproterozoic basement in the South Jiangxi area. Firstly, this result revises the previous determination of the Lujing kimberlite-like rock as Caenozoic by K-Ar and Rb-Sr dating method, and provides new correct data for investigating the evolutionary history of tectonic structures of the South Jiangxi area. Secondly, this result indicates that the transformation of the tectonic system in the late Yanshanian period is related to the interaction of crust and mantle, and the magma of the Lujing kimberlite-like rock may have originated from enriched mantle.