[1] Univ Paris Diderot, CNRS, Inst Phys Globe, IMPMC, F-75005 Paris, France
[2] Geol Survey Western Australia, Perth, WA 6004, Australia
[3] Univ Bergen, Dept Earth Sci, Ctr Geobiol, N-5007 Bergen, Norway
[4] Univ Liege, Dept Geol, B-4000 Liege, Belgium
[5] Univ Paris 07, CNRS, Inst Phys Globe, Lab Geochim Isotopes Stables, F-75005 Paris, France
[6] Museum Natl Hist Nat, CNRS, Dept Hist Terre Geol, UMR 5143, F-75005 Paris, France
[7] Univ Cape Town, Africa Earth Observ Network, ZA-7700 Rondebosch, South Africa
[8] Univ Cape Town, Dept Geol Sci, ZA-7700 Rondebosch, South Africa