1. Department of Geological Sciences, Central Washington University, 400 E. University Way, Ellensburg, Washington 98926-7418, USA
2. Department of Earth System Science, Stanford University, 473 Via Ortega, Room 140, Stanford, California 94305-4216, USA
3. Department of Earth Sciences, 1272 University of Oregon, Eugene, Oregon 97403-1272, USA
4. GNS Science–Te Pu Ao, P.O. Box 30-368, Lower Hutt 5040, New Zealand