1. School of Geography and Earth Sciences, McMaster University, Hamilton, Ontario, L8S 4K1 Canada, Department of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, Canadian Light Source, Inc., University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C6, Canada, and Brockhouse Institute for Materials Research and Departmentof Chemistry, McMaster University, Hamilton, Ontario L8S 4M1, Canada