Water And Geochemical Characteristics Of Peridotite Xenoliths In Yangyuan Cenozoic Basalts From Hebei Province ,china

Major and trace elements concentrations of minerals from peridotite xenoliths hosted by Cenozoic basalts in Yangyuan, Hebei Province, eastern China were obtained by electron microprobe (EMP) and laser ablation ICP-MS (LA-ICP-MS) respectively. The results suggest that the peridotite xenoliths are relicts of primary mantle after different degree of partial melting and have undergone mantle metasomatism induced by silicate melt. Micro-FTIR analysis demonstrates that both clinopyroxene and orthopyroxene display prominent OH absorption bands,and the calculated water content (H2O wt.) of clinopyroxene and orthopyroxene range from 30 to 654 ppm and from 14 to 225 ppm respectively. Water contents in three localities have significantly difference. The 1# and 2# sample locations have relative low water content with clinopyroxene and orthopyroxene ranges from 30 to 64ppm and from 14 to 26ppm. The 3# sample location has higher water content with clinopyroxene and orthopyroxene ranges from 258 to 654ppm and from 129 to 225ppm. The difference of water content may reflect mantle lithosphere which present by mantle xenoliths may have different evolution history. The source region of 3# sample location peridotite xenolith may be new accretion lithospheric mantle directly from asthenosphere and not affect by thermo perturbation.