Distribution of rare earth elements in rock-forming minerals from mafic-ultramafic massifs of the East Sakhalin ophiolite association

HREE over LREE is one of typomorphic features of orthopyroxenes [Lesnov, 2007b]. Some orthopyroxenes, including those from the Sakhalin massifs, are abnormally enriched in LREE; therefore, their REE patterns are negatively sloped. The LREE enrichment of these orhopyroxenes is probably due to the minor amounts of structural (isomorphic) REE impurities and the varying amount of nonstructural REE impurities. The latter are localized in the grain microcracks and, probably, in fluid microinclusions [Lesnov, 2007b].