Gas hydrates in nature

Anne Trehu and ODP Leg 204 Science Party

Gas hydrate is an ice-like compound of water and methane that forms at conditions found beneath the seafloor on continental margins around the world.  Because methane is a powerful greenhouse gas, sudden destabilization of the methane trapped in gas hydrates may be a factor in global climate change.  This methane may also be an energy resource for the future.  Quantifying the amount of methane present beneath the seafloor and the rate at which it forms, however, presents unique challenges since the material being studied decomposes when it is brought to the sea surface.  After a brief overview of global gas hydrate occurrences, we will look in more detail at one of the best studied gas hydrate deposits in the world, located on the Oregon continental margin. Multidisciplinary studies over the past decade, including a dedicated Leg of the Ocean Drilling Program in 2002, have focused on the distribution and concentration of hydrate beneath the seafloor, the fate of methane released to the water column, and the dynamics of gas hydrate formation and destabilization.