Characteristics of deep-derived enclave and its zircon LA-ICP-MS U-Pb age of Machangqing complex, Yunnan Province
云南马厂箐岩体中深源包体特征及其锆石LA-ICP-MSU-Pb年龄

Machangqing complex is an important part of alkali-rich porphyry belt in western Yunnan. The deep-derived mafic enclaves that found in Machangqing complex are significant for studying the origin and evolution of alkali-rich porphyry, ore-forming process, and regional geodynamics. According to the geological features of the enclaves, the author analyzed the zircons from enclaves with the LA-ICP-MS and obtained a U-Pb weighted average age of 35.13±0.23Ma (MSWD=0.64). This age is consistent with the age of granite porphyry (35.0±0.2Ma) and porphyritic granite (33.78±0.21Ma) which are the host rocks of enclaves. The Th/U value and Ti thermometer tempetature of zircons from enclaves and host rocks suggest that the enclaves are from magma mixing. Studies show the Machangqing alkali-rich porphyry is the mixture of crust-derived and mantle-derived magma enclaves and their host rocks have the similar magma evolution process and the injection of mantle-derived magma is a key factor to the ore-formation of this series magma.