Exsolution kinetics of majoritic garnet from clinopyroxene in subducting oceanic crust

► We measured exsolution kinetics of majoritic garnet from clinopyroxene. ► The reaction may be kinetically inhibited at low temperatures in subducting plate. ► We constructed the phase relations of subducting MORB taking the exsolution kinetics. ► The density of metastable MORB is much lower than that of equilibrium MORB.