Lithium isotopic geochemistry in subduction zones:Retrospects and prospects

Subduction-zone was composed of many complex processes,including the releasing of fluid,fluid/rock interactions,partial melting,isotopic fractionations,etc.As Li isotopes(6 Li and 7 Li)have relative massdifference up to 16%,being the largest among metal elements,they have the advantages to be used to trace various geological processes.Most importantly,during crust/mantle cycling in deep subduction zones,the surface materials and mantle rocks have strong contrast in Li isotopic composition,making Li isotope a potential tracer for subduction related processes from the onset of subduction,to the release of Li from subducted slab and interaction with mantle wedge rocks,and finally the fate of Li in slab-derived fluids and residual slab.Moreover,the Li isotopic composition of subducting output materials can provide information for global Li circulation.With developments in measurement and expansion of Li isotope database,Li isotope will provide more inference for subduction processes and be a more powerful tracer.