1. Geosciences Research Division Scripps Institution of Oceanography University of California San Diego La Jolla California 92093–0244 USA
2. Department of Geology University of Maryland College Park Maryland 20740 USA
3. Department of Geology and Geophysics Yale University New Haven Connecticut 06511 USA
4. Department of Earth and Space Sciences University of Washington Seattle Washington 98195 USA
5. Department of Earth and Planetary Sciences University of Tennessee Knoxville Tennessee 37996 USA