1. Department of Geology, Saint Mary's University, Halifax, NS B3H 3C3, Canada
2. Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139
3. Nova Scotia Department of Natural Resources and Renewables, Government of Nova Scotia, Halifax, NS B3J 3J9, Canada
4. Applied Petroleum Technology Ltd., Calgary T3A 2M3, Canada
5. Geomicrobiology Group, University of Calgary, Calgary, AB T2N 1N4, Canada