Ultramafic xenoliths from Damaping (Hannuoba region, NE-China): Petrogenetic implications from crystal chemistry of pyroxenes, olivine and Cr-spinel and trace element content of clinopyroxene

摘要: Abstract Olivine, orthopyroxene, clinopyroxene and spinel from 16 different lherzolite mantle xenoliths Damaping (Hannuoba region, NE-China) have been analyzed by X-ray single crystal diffraction electron microprobe to define their structure, chemistry cation distribution. LA-ICP-MS analysis has carried out on clinopyroxenes determine LILE (Large-Ion Lithophile Elements), HFSE (High Field Strength Elements) REE (Rare Earth contents. These latter Depleted, Enriched, U-shaped Transitional CI-normalized patterns suggesting that the xenolith suite here studied experienced at least two metasomatic events related porous flow percolation of melts with tholeiitic alkaline affinity, respectively. The distribution mineral phases allowed determination intra- inter-crystalline temperatures equilibration. closure temperature intra-crystalline reactions for constituent is in range 600–800 °C, a relatively slow cooling rate, while interval found 866–1048 °C. pressure conditions estimated Hannuoba through structural considerations correspond depth about 50–60 km, consistent Moho beneath area, which 42 km. pressures equilibration, as cell T site volumes clinopyroxenes, compared trace element signatures; they demonstrate formed are not restricted specific region mantle, testifying metasomatism took place depths mantle.