Processes and consequences of deep subduction

Abstract

Subduction of slabs of oceanic lithosphere into the deep mantle involves a wide range of geophysical and geochemical processes and is of major importance for the physical and chemical evolution of the Earth. For example, subduction and subduction-related volcanism are major processes through which geochemical components are recycled between the Earth’s crust, lithosphere and mantle. A large proportion of the world’s earthquakes and volcanoes are related to subduction. Volcanism results from a range of processes including dehydration, melting and melt migration. The deepest known earthquakes occur in subducted lithosphere at depths of 660–700 km but their cause, which has long fascinated geophysicists, is still enigmatic. In addition, the motion and velocities of lithospheric plates at the Earth’s surface are controlled largely by the buoyancy forces that drive subduction.