1. 1Department of Geosciences, Penn State University, University Park, Pennsylvania 16802, USA
2. 2Department of Resources and Environmental Engineering, Guizhou University, Caijiaguan, Guiyang 550003, Guizhou Province, P.R. China
3. 3Geosciences Department, Trinity University, San Antonio, Texas 78212, USA
4. 4Department of Geological Engineering, Middle East Technical University, Ankara, 06800, Turkey
5. 5Department of Earth and Planetary Sciences, Stanford University, Stanford, California 94305, USA