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Project Progress

Stability of methane hydrates in the presence of high salinity brines on Mars

Progress report

Recent observations of methane in the highly oxidizing atmosphere of Mars suggest that methane has been added relatively recently. Several mechanisms for recent methane release have been proposed in the scientific literature including subsurface biological methanogenesis, abiogenic hydrothermal and/or volcanic activity, weathering of ultramafic deposits to serpentenites, dissociation of methane hydrates, atmospheric photolysis, or addition of organics via bolide impact. This laboratory study examines the effects of increasing salinity on gas hydrate stability and compares estimates of the Martian geothermal gradient to methane and carbon dioxide hydrate stability fields in the presence of high salinity brines. The results demonstrate that salinity increases alone result in a significant decrease in the predicted hydrate stability zone under conditions inferred to exit in the Martian subsurface. Thus, lateral or vertical movement of brines in the Martian subsurface may be a driving force in methane hydrate destabilization. Active thermal and/or pressure fluctuations are not required in order for methane hydrates to be the source of atmospheric methane.