123 Planetary Geology: Brother Mars, Sister Venus

Tuesday, 24 October 2006
8:00 AM - 12:00 PM

SERPENTINIZATION AND THE INORGANIC SYNTHESIS OF H2 ON PLANETARY SURFACES

Paper number: 123-10
Program: Technical Sessions
Time: 10:15 AM – 10:30 AM

Authors

Abstract

The near-surface inorganic synthesis of molecular hydrogen (H2) is a fundamental process relevant to the origins and to the sustenance of early life on Earth and potentially other planets. Hydrogen production through the decomposition of water is thought to be a principal reaction that occurs during hydrothermal alteration of olivine (serpentinization). Here, we evaluate how the composition of olivine in the forsterite (Mg2SiO4)-fayalite (Fe2SiO4) binary system governs the production of H2 via serpentinization reactions over a range of pressures (1 bar to 5 kbar) and temperatures (0-500oC) using the geochemical modeling program SUPCRT92. Our results demonstrate that less Fe2+ in olivine will produce more H2 where copious amounts of H2 are produced only when the olivine undergoing alteration (serpentinization) contains 1 to 50 mole percent Fe. In general, life should have a chance to succeed on rocky, volcanic planets where olivine compositions are greater than Fo50 and less than Fo100 and would require alternative routes when compositions are less than Fo25.