1. Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada.
2. Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada.
3. Department of Geology & Petroleum Geology, University of Aberdeen, Aberdeen, UK.
4. Geomicrobiology Research Group, Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR), Open University, Milton Keynes, UK.