You Shenggang1,Guo Qian1,Geng Xiaojin2,Zeng Chunlin3
1.College of Geosciences and Survey Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;2.College of Management,China University of Mining and Technology(Beijing),Beijing 100083,China;3.Chongqing Institute of Geology and Mineral Resources,Chongqing 400042,China