1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, P. R. China
2. Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, P. R. China
3. College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
4. General Prospecting Institute of China National Administration of Coal Geology, Beijing 100039, P. R. China
5. Department of Ecosystem Science and Management, Materials Research Institute, 204 Energy and the Environment Laboratory, The Pennsylvania State University, University Park, PA 16802, USA