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6889294 
Journal Article 
Phlogopite-amphibole-pyroxenite xenoliths in Langao, Shaanxi Province, China: Evidence for mantle metasomatism 
Xu, X; Huang, Y; Xia, L; Xia, Z; , 
1997 
Yes 
Chinese Journal of Geochemistry
ISSN: 1000-9426
EISSN: 1993-0364 
16 
4 
318-329 
English 
Phlogopite-amphibole-pyroxenite xenoliths contained in the alkali basic-ultrabasic subvolcanic complex in Langao, Shaanxi Province, are composed of diopside, Ti-rich pargasite, phlogopite apatite, sphene and ilmenite, which have subsolidus metamorphism-deformation textures such as triple-points cataclastic boundaries and kink-bands. Mineral chemical characteristics show that the diopside, Ti-rich pargasite and phlogopite are derived from the mantle and are the products of mantle metasomatism. Compared with normal mantle-derived spinel-lherzolites, the xenoliths are enriched in TiO2, Fe2O3, CaO, Na2O and K2O, with apparent depletion in MgO. Chondrite-normalized REE patterns and primordial-mantle normalized trace elements data show that they are enriched in REE (especially LREE) and incompatible trace elements. The petrographic, mineralogical and petrochemical characteristics indicate that the xenoliths are metasomatized mantle xenoliths, which offers the evidence for mantle metasomatism and represents the anomalous mantle beneath the Early Paleozoic rift in northern Daba Mountains. The agents of mantle metasomatism are probably derived from the rising of mantle hot plumes. The processes of metasomatism varied from limited-range fluid metasomatism in deep mantle (>90 km) to pervasive metasomatism of silicate melt. 
amphibole; metasomatism; phlogopite; pyroxenite; xenolith; China, Shaanxi Province, Langao