1. Department of Earth Sciences, St Francis Xavier University, Antigonish, Nova Scotia, B2G 2W5, Canada
2. Earth Dynamics Research Group, the Institute for Geoscience Research (TIGeR), School of Earth and Planetary Sciences, Curtin University, WA 6845, Australia
3. School of the Environment, Geography and Geosciences, University of Portsmouth, Portsmouth PO1 3QL, UK
4. Instituto Geológico y Minero de España (IGME), C/Ríos Rosas, 23, 28003 Madrid, Spain