University of Toronto, Department of Geology, 22 Russell St., Toronto, ON M5S 3B1, Canada
NASA Goddard Space Flight Center, Planetary Geodynamics Laboratory, Greenbelt, MD 20771, USA; Scripps Institution of Oceanography, Institute for Geophysics and Planetary Physics, UC San Diego, La Jolla, CA 92039, USA
UC Santa Cruz, Earth and Planetary Sciences, Santa Cruz, CA 95064, USA
Texas Tech University, Department of Geosciences, Lubbock, TX 79409, USA