1. Division of Geological and Planetary Sciences, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
2. ExxonMobil Upstream Research Company, Houston, TX, USA.
3. Division of Geochemistry, Petrobras Research and Development Center (CENPES), Rio de Janeiro, RJ, Brazil.
4. U.S. Geological Survey, Denver Federal Center, Denver, CO, USA.
5. Department of Geology, Amherst College, Amherst, MA, USA.
6. Power, Environmental, and Energy Research Institute, Covina, CA, USA.
7. GasConsult International Inc, Berkeley, CA, USA.