1. Department of Geosciences and Centre for Earth Evolution and Dynamics (CEED), University of Oslo, PO Box 1047, 0316 Oslo, Norway
2. School of Earth and Environmental Sciences (SEES), University of Portsmouth, Burnaby Road, Portsmouth PO1 3QL, UK
3. College of Life and Environmental Sciences, University of Exeter, Prince of Wales Road, Exeter EX4 4PS, UK