This study focuses on the geology, geochemistry, zircon U–Pb geochronology, and tectonic settings of the three types of seamount basalts from the Xingshuwa subduction accretionary complex in the Xar Moron area in the eastern margin of the Central Asian Orogenic Belt (CAOB). The seamount remnants are composed of carbonate “cap” sediments, large volumes of pillow and massive basalts, carbonate breccia slope facies, and radiolarian cherts. Group 1 basalts are characterized by high contents of P₂O₅ and TiO₂ with alkaline affinity and LREE enrichment, indicating that they are derived from the intraplate magma. Group 2 basalts have N-mid-oceanic ridge basalt (MORB) LREE depletion patterns, indicating that they were formed at a mid-oceanic ridge. Group 3 basalts have shown distinct Nb depletion and high Th/Yb ratios, indicating that they were generated in an island arc tectonic setting. The zircon U–Pb age of Group 1 basalt sample XWT18-131 is 576.4 ± 9.4 Ma, suggesting that the oceanic island seamount was the product of intraplate magmatism related to a mantle plume or “hot spot” in the Late Neoproterozoic. The zircon U–Pb age of Group 2 basalt sample XWT18-132 is 483 ± 22 Ma, indicating that the Paleo-Asian Ocean (PAO) was continuously expanding in the Early Ordovician. The zircon U-Pb age of Group 3 basalt sample XWT18-101 is 240.5 ± 8.2 Ma, suggesting that this area underwent the evolution of ocean-continent transition and developed toward continentalization during the Middle Triassic. Thus, we believe that there were mantle plume-related intraplate magmatism and intraoceanic subduction during the evolution of the PAO, and the CAOB may be an evolution model of intraoceanic subduction and mantle plume magmatism complex.

中文翻译：

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中亚造山带东缘Xar Moron地区星树洼俯冲增生杂岩中海山遗迹的地球化学和构造历史

本研究重点研究中亚造山带东缘Xar Moron地区星树洼俯冲增生杂岩中三种海山玄武岩的地质、地球化学、锆石U-Pb年代学和构造背景。海山遗迹由碳酸盐“盖”沉积物、大量枕状和块状玄武岩、碳酸盐角砾斜坡相和放射虫燧石组成。第 1 族玄武岩的特点是 P ₂ O ₅和 TiO ₂含量高具有碱性亲和力和轻稀土元素富集，表明它们来自板内岩浆。第 2 组玄武岩具有 N 大洋中脊玄武岩 (MORB) 轻稀土耗尽模式，表明它们形成于大洋中脊。第 3 组玄武岩显示出明显的 Nb 耗尽和高 Th/Yb 比率，表明它们是在岛弧构造环境中生成的。第1组玄武岩样品XWT18-131的锆石U-Pb年龄为576.4±9.4 Ma，表明该洋岛海山是新元古代晚期与地幔柱或“热点”相关的板内岩浆作用的产物。第2组玄武岩样品XWT18-132的锆石U-Pb年龄为483±22 Ma，表明古亚洲洋（PAO）在早奥陶世持续扩张。第 3 组玄武岩样品 XWT18-101 的锆石 U-Pb 年龄为 240.5 ± 8.2 Ma，表明该地区在中三叠世经历了海陆过渡的演化，向大陆化发展。因此，我们认为在PAO演化过程中存在与地幔柱相关的板内岩浆作用和洋内俯冲作用，CAOB可能是洋内俯冲和地幔柱岩浆作用复合体的演化模式。