1. Equipe Géobiosphère Actuelle et Primitive, Institut de Physique du Globe de Paris, CNRS and Université Denis Diderot, 4 place Jussieu, 75005 Paris cedex, France.
2. Earth System Science Interdisciplinary Center, Department of Geology, University of Maryland, College Park, MD 20742, USA.
3. Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia.