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Magmatic evolution and W-Sn-U-Nb-Ta mineralization of the Mesozoic Jiulongnao granitic complex, Nanling Range, South China TEXT SIZE: A A A
South China is famous for its large-scale mineralization genetically related to widespread Mesozoic granites. The Jiulongnao complex is one of the largest intrusions in southern Jiangxi Province, and is closely associated with W-dominated polymetallic mineralization. The complex comprises four intrusive phases (I-IV). Phase I consists of medium- to coarse-grained, biotite granite, whereas medium- to coarse-grained, porphyritic, biotite granite and muscovite-bearing granite comprise Phase II. Phase III is composed of medium- to fine-grained, porphyritic, biotite granite and Phase IV consists of medium- to fine-grained, garnet- and biotite-bearing granite. These intrusive phases have LA-ICP-MS zircon U-Pb ages of 160.9 +/- 0.6 Ma, 158.6 +/- 0.7 Ma, 157.0 +/- 1.5 Ma and 154.1 +/- 1.2 Ma, respectively. All of the granites are enriched in Rb, Th, U, Ta and Pb, and significantly depleted in Eu, Ba, Nb, Sr, P and Ti. They have epsilon(Hf)(t) and epsilon(Nd)(t) values ranging from -17.9 to -8.2, and -10.7 to -9.8, respectively, with two-stage Hf model ages of 1.7-2.3 Ga. They are S-type granites derived by partial melting of Paleo-Proterozoic metasedimentary rocks. The four phases have T-zr of 746-760 degrees C, 712-802 degrees C, 798-810 degrees C, and 648-731 degrees C, respectively. Oxygen fugacities of Phases I to III display a decreasing trend but Phase IV has much higher oxygen fugacity in its early stage, which decreased in the late stage. The four phases have different accessory mineral assemblages: Phase I is characterized by an assemblage of zircon, apatite, fergusonite, thorite and uraninite, whereas Phase II is rich in thorite, uraninite, REE-bearing minerals (e.g., monazite, fergusonite and xenotime) and fluorite. Monazite is the main accessory mineral in Phase III, whereas Phase IV contains a wide range of minerals, including thorite, uraninite, Nb-Ta-bearing minerals (e.g., fergusonite and pyrochlore), cassiterite and rutile. These mineral assemblages, together with other geological and geochemical features, suggest that W mineralization was genetically related to Phases I, II and IV, whereas U mineralization was most extensive in Phase II. Sn, Nb and Ta mineralization was associated with the highly fractionated of magmas of Phase IV.
 

Publication name

 ORE GEOLOGY REVIEWS, 94 414-434; 10.1016/j.oregeorev.2018.02.015 MAR 2018

Author(s)

 Guo, Na-Xin; Zhao, Zheng; Gao, Jian-Feng; Chen, Wei; Wang, Deng-Hong; Chen, Yu-Chuan

Corresponding author(s) 

 ZHAO Zheng 
 kevin8572@hotmail.com  
 Chinese Acad Geol Sci, Inst Mineral Resources, MLR Key Lab Metallogeny & Mineral Assessment, Beijing 100037, Peoples R China 

Author(s) from IGCAS   GAO Jianfeng

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