Dehydration of lawsonite in cold subduction zones traced by experimental Quantum Crystallography methods

Water continuously enters the mantle through subduction zones where its transport and release occurs inducing volcanism and seismicity. The high-pressure stability of hydrated metamorphic phases such as lawsonite mineral and their importance in transporting water into Earth’s deep interior are of great interest for a number of disciplines, such as mineralogy, geophysics and solid-state physics. Lawsonite (CaAl2Si2O7(OH)2xH2O) is an abundant hydrous mineral in oceanic crust, sediments and metasomatic rocks in most subduction zones. It is particularly interesting because of its high overall water content, 11.5 wt % and its role as a dominant water carrier in subducted crust. The aim of this proposal is to perform high resolution and high completeness single crystal X-ray diffraction experiments of lawsonite at temperatures and pressures corresponding to cold subduction zone environment since its phase and dehydration process still remains unknown under these conditions.