Simulation of bottom boundaries of abiotic methane hydrate stability zone in some marine serpentinization areas

Fluids circulating through active serpentinization systems are often highly enriched in methane. When the fluid enriched in abiotic methane migrates upward, gas hydrate could form if there occur suitable thermodynamic conditions. In order to investigate the thermodynamic conditions of the stability zone of abiotic methane hydrate in marine serpentinization areas, we calculated the depth of the bottom boundaries of gas hydrate stability zone in three distinctive serpentinization areas, i.e. the Mariana forearc serpentinized mud volcanos, the Fram strait (an ultraslow- spreading ridge) and the Lost City (a slow spreading ridge). Our results show that the thermodynamic conditions are satisfied for forming the hydrate stability zone in the areas of Mariana forearc serpentinite mud volcanos and the ultraslow-spreading ridge at the Fram Strait. Calculation shows the depth of the bottom boundaries of gas hydrate stability zone is around 858～2515 mbsf at Mariana forearc mud volcano area and 153～232 mbsf at the Fram Strait. However, the temperature of vent fluids found at the Lost City is relative higher than needed for the formation of gas hydrate stability zone.