Eclogite facies garnet-pyroxenolite xenolith in Hannuoba area: New evidence of magma underplating.

Eclogite facies garnet-pyroxenolite xenoliths in Hannuoba area show the typ ical layered cumulate structures and crystalloblastic textures of granulite facies. The mineral compositions, equilibrated P-T conditions and REE geoc hemistry of the xnolith reveal its mantle-derived genesis. All these facts indicate that the mantle-derived magma underplates in the top of the upper mantle and forms the mafic cumulate, then the cumulate experiences some met amorphism of eclogite facies. The eclogite facies xenolith, accomponied wit h the granulite facies xenolith, provides new evidence of the existence of the crust-mantle transitional zone.