HR: 0830h
AN: P51B-0442    [PDF]
TI: Gas Hydrate Stability at Low Temperatures and High Pressures
AU: * Marion, G M
EM: gmarion@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Kargel, J S
EM: jkargel@usgs.gov
AF: U.S. Geological Survey, 2255 N. Gemini Dr., Flagstaff, AZ 86001 United States
AU: Catling, D C
EM: davidc@atmos.washington.edu
AF: University of Washington, Dept. of Atmospheric Sciences, Seattle, WA 98195 United States
AB: Several papers have recently suggested that decomposition of gas hydrates could have played an important role in the geologic history of Mars and Europa. Gas hydrates form in porous sediments under low temperatures and high pressures. The FREZCHEM model was developed to predict chemical equilibria over the temperature range from -70 to 25$\deg$C and the pressure range from 1 to 1000 bars using the Pitzer equations, which are valid to high ionic strengths. The objectives of this paper were to (1) add gas (carbon dioxide and methane) hydrate chemistry to the FREZCHEM model, and (2) use the model to examine hypothetical gas hydrate chemistries on Mars and Europa. For the gas hydrate model, key variables and constants that were quantified as functions of pressure and temperature were solubility products, gas solubilities, and activity coefficients. Based on this work, new state-of-the-art stability diagrams were developed for carbon dioxide and methane hydrates in pure water and seawater. Applications to Mars a
DE: 1030 Geochemical cycles (0330)
DE: 1045 Low-temperature geochemistry
DE: 1050 Marine geochemistry (4835, 4850)
DE: 1060 Planetary geochemistry (5405, 5410, 5704, 5709, 6005, 6008)
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting