1. The University of Texas at Austin, Bureau of Economic Geology, John A. and Katherine G. Jackson School of Geosciences, Austin, Texas 78713, USA.
2. Northwestern Polytechnical University, School of Computer Science, Xi’an 710072, China.
3. University of Science and Technology of China, School of Earth and Space Sciences, Hefei 230026, China. (corresponding author)
4. Microsoft, Applied Science Group, Redmond, Washington 98052, USA.