XU Heng1,2, CUI Yin-liang1,3, ZHOU Jia-xi4, ZHANG Miao-hong2, RONG Hui-feng2, JIANG Yong-guo3
(1.Faculty of Land Resources Engineering, Kunming University of Science and Technology, Kunming 650093, China;
2.Nonferrous Metal Geological Survey of Yunnan Nonferrous Metals Geological Bureau, Kunming 650216, China;
3.Yunnan Nonferrous Metals Geological Bureau, Kunming 650051, China;
4.State Key Laboratory of Mineral Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China)
Abstract: Located in the field between Jinshajiang-Red River and Binchuan-Chenghai faults, Baofengsi alkaline porphyries in Binchuan City, Yunnan province, China is an important part of Jinshajiang-Red River alkali-rich porphyry belt. The porphyry consists of fine crystal biotitic granite porphyry and coarse-grain granite porphyry. LA-ICP-MS zircon U-Pb dating of two porphyry samples shows that 206Pb/238U weighted average age are 34.99±0.37 Ma (MSWD＝2.1, n=20) and 33.53±0.27 Ma (MSWD＝1.4, n=19), respectively. These ages suggest that Baofengsi alkaline porphyries had formed during the Paleogene Eocene and are consistent with the peak ages (45～30 Ma) of the alkali-rich porphyry magmatism in Jinshajiang-Red River alkali-rich porphyry belt and India-Asian late collision transformation time (41～26 Ma), suggesting that those porphyries formed under India-Asian late collision extended setting. The LA-ICP-MS zircon U-Pb ages of Baofengsi alkaline porphyry are also similar to the metallogenic peak ages of porphyry-type deposit (34±2 Ma) in western Yunnan Province, indicating that those porphyries have an ore-forming potentiality.
Keywords: alkaline porphyry; LA-ICP-MS; zircon U-Pb age; geological implication; Baofengsi; Binchuan City; Yunnan Province
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ACTA MINERALOGICA SINICA Vol. 35, No. 4, 2015, Page 457-462
