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Clathrate Hydrates from Mars? Geological, Geophysical, and Resource Implications

Kargel, Jeff 1
1 Hydrology & Water Resources, University of Arizona, Tucson, AZ.

Mars has a far wider range of pressure-temperature stability of CO2 and CH4 clathrate hydrates compared to Earth, and it has undergone the types of sedimentary and aqueous processes whereby prodigious amounts of clathrates could have have formed. An issue is the inventory of clathrate-forming gases on Mars. It has a CO2 atmosphere, and traces of CH4 occur in the atmosphere. Methane has a spatially heterogeneous pattern, so it must be supplied from regional or local sources at rates that work with atmospheric mixing and photolytic destruction so as to produce the distribution. The ultimate source of CH4 is unclear; it could be metamorphic or biogenic. Many geologic features might relate to the catastrophic or gradual destruction of subsurface clathrates, release of gas or gas-saturated water, and attendant volume changes in the crust. Most dramatic are chaotic terrains, some of which seems to have involved relatively catastrophic or violent releases of gas-saturated water, such as from a ruptured permafrost-confined, gas-saturated aquifer. Features appearing to be mud volcanoes and shallow crustal diapirs also may be related to gas overpressure and clathrate dissociation.

If clathrates are abundant on Mars, they may contribute to the establishment of geothermal conditions whereby clathrate dissociation would occur. Clathrate hydrates have very low thermal conductivities, and massive deposits would hinder the conductive escape of geothermal heat from the Martian interior. The presence of massive clathrates would lead to high temperatures reaching to the P-T dissociation thresholds of clathrates at shallow depths; this phenomenon could be a self-limiting behavior whereby formation of clathrates plant the seeds of their destruction. A CO2 cycle may exist whereby ground fluid circulation moves dissolved gases to places where clathrates are stable. CH4 clathrate either would be gradually depleted in the Martian crust or else there must exist a source of new methane.

Methane clathrate one day might be exploited as a resource. Methane could be utilized with O2 for rocket propellant and surface mobility. Carbon and hydrogen derived from methane may have myriad industrial chemical uses in the establishment of an industrial economic base on Mars. With salts and other raw materials, an early Mars base may establish manufacture of ceramics, plastics, fertilizers, and other basic industrial materials. CH4 should be an early exploration priority.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009