1. Department of Geological Sciences; University of Michigan; 1000 North University Avenue,; Ann Arbor; Michigan; 48109-1005; USA
2. Laboratoire de Pétrologie Magmatique, Faculté des Sciences de Marseille Saint Jérome; Université Paul Cézanne Aix-Marseille III; Case 441,; F-13397; Marseille CEDEX 20; France
3. School of Ocean and Earth Science, National Oceanography Centre, Southampton; University of Southampton; European Way,; Southampton; SO14 3ZH; UK
4. Department of Earth Sciences; University of Western Ontario; London, Ontario; N6A 5B7; Canada