High abundances of noble gas and chlorine delivered to the mantle by serpentinite subduction

Abstract

The Earth's mantle contains non-radiogenic noble gas isotopes that imply transfer of noble gases from the atmosphere into the mantle through subduction. Hydrated serpentinite rocks within subducting oceanic lithosphere are recognized as key carriers of water and chlorine, but the pathways for noble gas subduction have been poorly constrained. Here we analyse the concentration of noble gas isotopes and halogens in rocks from the Ligurian Alps, Italy and the Betic Cordillera, Spain. These rocks and the fluid inclusions trapped within them preserve a record of serpentinite dehydration during progressively deeper stages of subduction. We find that the noble gas and halogen signature of serpentin..