1. Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
2. School of Resources and Environment, Hefei University of Technology, Hefei 230026, China
3. China Geological Survey (Nanjing Center), Nanjing 210016, China
4. Department of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1, Canada
5. School of Earth Sciences and Engineering, Sun Yat-Sen University, Guangzhou 510275, China