1. School of earth science and resources Chang’an, University; Xi’an 710064 Shaanxi China
2. MNR Key Laboratory of Metallogeny and Mineral Resource Assessment, Institute of Mineral Resources; China Academy of Geological Sciences; Beijing 100037 China
3. Geological Survey of Gansu Province; Lanzhou 730030 Gansu China
4. Changba Pb-Zn Mine of Baiyin Nonferrous Metals Company; Chengxian 742500 Gansu China