揚(yáng)子西緣新元古代早期大洋俯沖作用

——來(lái)自川西天全閃長(zhǎng)巖成因的制約

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Abstract：Magmatic rocks exposed along the western margin of the Yangtze Block play a crucial role in reconstructing the Neoproterozoic tectonic evolution of the Yangtze Block.This study investigates diorite plutons in the Tianquan area of western Sichuan through U-Pb zircon dating， whole-rock major and trace element analysis， zircon Lu-Hf isotopic analysis， and whole-rock Sm-Nd isotope systematics. The Tianquan diorites formed 807～ （204號(hào) 804Ma ，and are characterized by moderate w（SiO2 0 55.71%～59.74% and low w（K2O）（1.10%～1.77%） ，belonging to thecalc-alkaline series.The diorites displayarc-type features，including enrichment in lightrare earth elements and large ion lithophile elements，depleted in high field strength elements，and significantly positive zircon εHf（t）（+10.0 to +12.9 Dandwhole-rock εNd（t）（+4.25 to +4.43 ）.Relativelyhigh Ba/Th and low ThILa ratios suggest that the source was prmarily metasomatized by subduction-related fluids.The whole-rock geochemical signaturesand Nd-Hf isotopic compositions demonstrate that the Tianquan diorites originated from partial melting of a mantle wedge modified by subduction fluids，and the diorites were emplaced in an island arc environment.By integrating magmatic and sedimentary features along the western margin of the Yangtze Block， this study suggests that the western margin of the Yangtze Block was in a subduction tectonic setting in the early Neoproterozoic.

Key words： Tianquan diorite； geochemistry；Neoproterozoic；petrogenesis；western Yangtze Block

羅迪尼亞（Rodinia）超大陸形成是地質(zhì)歷史上一次重要的全球性大陸聚合事件，為宜居地球的形成奠定了重要基礎(chǔ)，一直備受全球地質(zhì)學(xué)家廣泛關(guān)注（Hoffman et al.，1998，2017;Cawood et al.，2013，2018;Dong etal.，2024a）。（剩余44562字）