论文部分内容阅读
The Cretaceous Xigaze ophiolite is best exposed at the central Yarlung Zangbo Suture Zone(YZSZ,Tibet)which also includes the Gangdese arc and the Xigaze forearc basin.This study reports new geochronological and geochemical data for this ophiolite to revisit its geodynamic and petrogenetic evolution.The Xigaze peridotites have low CaO and Al2O3 contents and U-shaped Rare Earth Element(REE)patterns,suggesting that they are residues after moderate to high degrees of partial melting and were modified by infiltration of Light Rare Earth Element(LREE)-enriched boninitic melts.The Xigaze crustal rocks belong to two groups: Mid-Ocean-Ridge-Basalt(MORB)-like rocks and boninitic rocks showing a uniform LREE depletion and flat to LREE enrichment on chondrite-normalized patterns,respectively.Geochemically,both groups show the influence of subducting oceanic slab-derived fluids.