Cause for a llama

Abstract

Subduction zones, where oceanic plates plunge into the deep Earth, were thought to be effective barriers to the recycling of noble gases back into the interior. But now a study of the xenon isotopic composition of mantle gases from a natural gas field in New Mexico suggests that heavy noble gases are reintroduced into the mantle at subduction zones, and that the main source of heavy noble gases in the Earth is recycled seawater. This finding provides an important constraint for future models of convection in the Earth.