1. Department of Earth Sciences, University of Geneva, 1205 Geneva, Switzerland
2. Present address: Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany.
3. Institute of Geochemistry and Petrology, ETH Zürich, 8092 Zürich, Switzerland
4. Present address: Memorial University of Newfoundland, CREAIT, CRC, and CFI Services (CCCS), Bruneau Centre for Research and Innovation, St. John’s, Newfoundland and Labrador A1C 5S7, Canada.