Peculiarities of Methane Clathrate Hydrate Formation and Solid-State Deformation, Including Possible Superheating of Water Ice

http://www.sciencemag.org/cgi/content/abstract/sci;273/5283/1843

Laura A. Stern, * Stephen H. Kirby, William B. Durham
Slow, constant-volume heating of water ice plus methane gas mixtures forms methane clathrate hydrate by a progressive reaction that occurs at the nascent ice/liquid water interface. As this reaction proceeds, the rate of melting of metastable water ice may be suppressed to allow short-lived superheating of ice to at least 276 kelvin. Plastic flow properties measured on clathrate test specimens are significantly different from those of water ice; under nonhydrostatic stress, methane clathrate undergoes extensive strain hardening and a process of solid-state disproportionation or exsolution at conditions well within its conventional hydrostatic stability field.
L. A. Stern and S. H. Kirby, U.S. Geological Survey, Menlo Park, CA 94025, USA. W. B. Durham, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.