An experimental study of trace element mobility during dehydration of lawsonite blueschist along different P-T paths: Implications for geochemical heterogeneity of Earth’s mantle

•LILEs can be significantly released during dehydration along both hot and cold subduction paths.•Water-bearing minerals can carry large amounts of Rb, Sr, Th, U and LREEs into deep mantle.•The mobilities of radioactive parent and radiogenic daughter (e.g. U-Pb, Th-Pb, Rb-Sr and Sm-Nd) are rather different during dehydration along different subduction paths.•Recycling of oceanic crust along a cold subduction path can lead to a geochemically heterogeneous mantle more efficiently than does along a hot path.