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Geochemistry and Tectonic History of Seamount Remnants in the Xingshuwa Subduction Accretionary Complex of the Xar Moron Area, Eastern Margin of the Central Asian Orogenic Belt
Acta Geologica Sinica-English Edition ( IF 3.5 ) Pub Date : 2021-01-08 , DOI: 10.1111/1755-6724.14646 Yang CHENG 1 , Qinghui XIAO 2 , Tingdong LI 2 , Yan LI 1 , Yuxu FAN 3 , Liquan XU 4 , Lingjun GUO 4 , Jinli PANG 4
Acta Geologica Sinica-English Edition ( IF 3.5 ) Pub Date : 2021-01-08 , DOI: 10.1111/1755-6724.14646 Yang CHENG 1 , Qinghui XIAO 2 , Tingdong LI 2 , Yan LI 1 , Yuxu FAN 3 , Liquan XU 4 , Lingjun GUO 4 , Jinli PANG 4
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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, 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 intraplate magma. Group 2 basalts display N-MORB LREE depletion patterns, indicating that they were formed at a mid-ocean 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 evolutionary path of ocean-continent transition, developing towards continentalization during the Middle Triassic. Thus, we believe that there was both mantle plume-related intraplate magmatism and intraoceanic subduction during the evolution of the PAO, the CAOB possibly being an evolutionary model of an intraoceanic subduction and mantle plume magmatism complex.
中文翻译：
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(CAOB)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年代学和构造环境。海山残余物由碳酸盐“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，表明它们来源于板内岩浆。第 2 组玄武岩显示出 N-MORB LREE 消耗模式，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，表明该地区经历了海陆过渡的演化路径，在中三叠世向大陆化发展。因此，我们认为在PAO的演化过程中同时存在与地幔柱相关的板内岩浆作用和洋内俯冲，CAOB可能是洋内俯冲和地幔柱岩浆作用复合体的演化模型。
更新日期：2021-01-08
中文翻译：
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(CAOB)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年代学和构造环境。海山残余物由碳酸盐“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，表明它们来源于板内岩浆。第 2 组玄武岩显示出 N-MORB LREE 消耗模式，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，表明该地区经历了海陆过渡的演化路径，在中三叠世向大陆化发展。因此，我们认为在PAO的演化过程中同时存在与地幔柱相关的板内岩浆作用和洋内俯冲，CAOB可能是洋内俯冲和地幔柱岩浆作用复合体的演化模型。
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