1. Dept. of Earth and Environmental Sciences, New Mexico Institute of Mining and Technology, 801 Leroy Place, 87801 Socorro, USA
2. New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, 87801 Socorro, USA
3. Deutsches GeoForschungsZentrum GFZ, Telegrafenberg, 14473 Potsdam, Germany
4. Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China
5. Department of Geology, University of Johannesburg, P.O. Box 524, Auckland Park, 2006, South Africa