1. China University of Geosciences, Beijing 100083, China
2. The First Exploration Bureau, CNACG, Handan, Hebei 056004, China
3. China University of Mining & Technology, Beijing 100083, China
4. Key Laboratory of Resource Exploration Research of Hebei Province, Hebei University of Engineering, Handan, Hebei 056038, China
5. China National Administration of Coal Geology, Beijing 100039, China