Trace element behavior during hydrous melting of a metasomatized garnet–peridotite was examined at subarc conditions.

Infiltration of an aqueous fluid into a dry peridotite results in D_U^{fluid–peridotite} > D_Th^{fluid–peridotite}, while penetration of a hydrous melt ends up with D_Th^{melt–peridotite} = D_U^{melt–peridotite}.

The fractionation among the HFSE at all pressures is high, with D_Th > D_Ta ≅ D_Nb > D_Hf ≅ D_Zr.

Garnet and clinopyroxene in mantle rocks in equilibrium with an aqueous fluid are characterized by significant high fitted D_o(3 +) for REE in the X site compared to the partitioning values when in equilibrium with a hydrous melt.

The fluid signature derived from equilibration with basaltic eclogite will not be modified significantly due to aqueous fluid–garnet–peridotite or hydrous melt–garnet–peridotite interaction.