The Yangla copper deposit is located in the middle zone of Jinshajiang suture zone. The Beiwu, Linong and Lunong granitoids exhibit a linear distribution from north to south in the ore district. The three granitoids have similar compositions of major, trace elements and Sr-Nd isotopes, indicating that they have a common magma source. They do not contain muscovite, and have high concentrations of SiO(2) (64% similar to 73%), K(2)O (2. 15% similar to 4. 05%) and low P(2)O(5) (0. 04% similar to 0. 11%) content. In addition, they have low delta((K(2)O + Na(2)O)(2)/(SiO(2)-43); 1.4 similar to 2. 4) and A/CNK (molecular Al(2)O(3)/(CaO + Na(2)O + K(2)O); 0.92 similar to 1. 11). The granitoids display significantly negative anomalies of Nb, Ta, Ti and P, obvious enrichment of LREE and Rb, Th, U and Pb. The 10000Ga/Al ratios (1. 7 similar to 2. 1) of those rocks are lower than typical A-type granites. Moreover, considering the slightly negative Eu anomalies, it is suggested that the three granitoids belong to high-K calc-alkaline, metaluminous-slightly peraluminous I-type granites. Compared with the continental crust (i. e., the Lincang granite and the Shaba granulite), the granites have lower ((87)Sr/(86)Sr)(i) (0. 7078 similar to 0. 7105) and higher epsilon(Nd) (t) (-5. 1 similar to -6.7), with ancient Nd two-stage model age (t(DM2) = 1. 5Ga). And there occur a number of coeval mafic microgranular enclaves (MMEs) in these granitoids, suggesting that mantle-drived magmas were involved in the source region (see in a separate article). By combining with comparative analyses of the tectonic settings, we propose a model in which the Beiwu, Linong and Lunong granitoids were generated under a late collisional or post-collisional setting. Decompression induced those mantle-derived magmas underplated and provided the heat for the anatexis of the crust. The hybrid melts (i. e., mantle-derived and the lower crustal magmas) and subsequent fractional crystallization could be responsible for the formation of the Beiwu, Linong and Lunong granitoids.

Publication name	ACTA PETROLOGICA SINICA　Volume: 27 　Issue: 9 　Pages: 2553-2566 　Published: SEP 201
Author(s)	Zhu JingJing; Hu RuiZhong; Bi XianWu; Zhong Hong; Chen Heng; Ye Lei; Long Fei
Corresponding author	ZHU Jingjing  zhujingjing-1103@163.com, huruizhong@vip.gyig.ac.cn  Chinese Acad Sci, Inst Geochem, State Key Lab Ore Deposit Geochem, Guiyang 550002, Peoples R China

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