ethane clathrate, also called methane hydrate, methane ice or « fire ice » is a solid clathrate compound (more specifically, a clathrate hydrate) in which a large amount of methane is trapped within a crystal structure of water, forming a solid similar to ice
ce sont bien des hydrates de carbone :
In the less common second type found near the sediment surface some samples have a higher proportion of longer-chain hydrocarbons (<99% methane) contained in a structure II clathrate. Carbon from this type of clathrate is isotopically heavier (δ13C is -29 to -57 ‰) and is thought to have migrated upwards from deep sediments, where methane was formed by thermal decomposition of organic matter. Examples of this type of deposit have been found in the Gulf of Mexico and the Caspian Sea.[8]
et ils reprrésentent un DOUBLE DANGER : pour les forages, mais aussi pour le réchauffement climatique car le permafrost par exemple en retient : son réchauffement libérerait des quantités considérables de méthane...
méthane : CH4
l
le C ne signifiant pas crétin je pense...