1. School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
2. Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
3. Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
4. Key Laboratory of Petroleum Resources, Lanzhou 730000, Gansu Province, China