Gas hydrate accumulation in deep-water marine sediments

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Abstract
The accumulation of gas hydrates largely depends on the spatial variability of gas solubility in pore waters. Within the submarine gas hydrate stability zone the solubility of methane in water significantly decreases towards the sea floor in response to temperature lowering. Gas hydrates can precipitate from methane-saturated water seeping up. They also accumulate from diffusing gas and segregated pore water within diffusion aureoles associated with the ascending fluid flows and with the zones where biochemical methane is generated at high rates. Hydrates more readily form in sediments where pore waters are relatively fresh and pores are rather large. The thermobaric gas hydrate stability zone is a geochemical barrier for hydrocarbon gases migrating from sediments into the sea water. However, the rising gas is not completely preserved in the hydrate.