Volatile Recycling in the Mantle Traced by Halogens in Mantle Peridotites and Serpentinites

Abstract

Since halogens (F, Cl, Br, and I) are highly volatile and partitioned into the liquid phase, they exist in high concentrations in surface reservoirs such as oceans, sediments, and crust. Their elemental ratios also vary greatly from reservoir to reservoir. Owing to these features, halogens are expected to be good tracers of the material exchange between the Earth's surface and mantle, especially the water recycling in the mantle. Halogens in mantle materials have been difficult to analyze by conventional methods due to their low concentrations, but recently, highly sensitive analysis has become possible by a combination of neutron irradiation and noble gas mass spectrometry. The halogen compositions of basaltic glasses at the mid-ocean ridges and hot spots, mantle peridotites, diamonds, and serpentinites have revealed the volatile (particularly water) recycling in the Earth's interior. In this talk, I will introduce the volatile recycling in the mantle traced by the halogen compositions of peridotites and serpentinites.