Geochemical evidence for melt migration and reaction in the upper mantle

摘要: THE segregation of melts from the Earth's upper mantle into crust is an important process in chemical evolution crust–mantle system. The processes melt formation and migration are inadequately understood, but some characteristics these can be inferred upper-mantle rocks exposed at surface. Horoman peridotite body northern Japan a layered rock. major-element compositions layers consistent with their as residues varying extents melting; however, abundances rare-earth elements (REE) require additional to have occurred1, such post-melting enrichment (metasomatism) resulting reaction migrating fluid phase. We report here that chondrite-normalized REE patterns clinopyroxenes show abrupt changes slope, which vary stratigraphic position rock type. These data modelled by chromatographic fractionation migrated through interacted peridotite, creating compositional heterogeneities mantle. In occur on scale length tens metres.