Clathrate Hydrates on Earth and in the Solar System

Abstract

The importance for solar system processes of inclusion of volatile species in water ice structures has been recognized now for several decades. Much interest is focused on clathrate hydrate, a crystalline phase of water ice in which other (generally more volatile) species such as methane, nitrogen, and noble gases stabilize the formation of a rather open structure of water ice (the “host”), into which the other species (the “guests”) can incorporate. This chapter has three main foci with respect to clathrate hydrate. First, we consider the role of clathrate hydrates on the Earth. We then provide a discussion of the possible existence of clathrate hydrate on Mars . In the third section we turn to the outer solar system, where clathrate hydrates have been invoked as carriers of volatile gases, but recent thinking has shifted focus to amorphous phases. For lack of space we assume most readers are familar with the basics of clathrate formation and terminology; those unfamiliar are referred to Lunine and Stevenson (1985) and Sloan (1997).