1. U.S. Geological Survey, 2255 North Gemini Drive, Flagstaff, Arizona 86001, USA
2. U.S. Geological Survey, MS 973, Menlo Park, California 94025, USA
3. Arizona Geological Survey, University of Arizona, Tucson, Arizona 85721, USA
4. Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA
5. New Mexico Institute of Mining and Technology, Department of Earth and Environmental Science, Socorro, New Mexico 87801, USA