1. Division of Geological and Planetary SciencesCalifornia Institute of TechnologyPasadena California USA
2. Now at: Department of Earth ScienceUniversity of California RiversideRiverside California USA
3. Graduate School of OceanographyUniversity of Rhode IslandNarragansett Rhode Island USA
4. Geosciences DepartmentUniversity of Texas at DallasRichardson Texas USA
5. Hawai'i Institute of Geophysics and Planetology, University of Hawai'i at ManoaHonolulu Hawaii USA
6. Department of Mineral SciencesNational Museum of Natural History, Smithsonian InstitutionWashington DC USA