1. INSTAAR and Geological Sciences, University of Colorado, Boulder, CO 80309–0450 USA.
2. Geophysical Laboratory, Carnegie Institution of Washington, 1051 Broad Branch Road, Washington, DC 20015, USA.
3. Department of Earth and Marine Sciences, Australian National University, Canberra, ACT 0200, Australia.
4. Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia.
5. Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia.