The petrology, geochronology and geochemistry of the mafic enclaves in the Mid‐Late Triassic Jiefangyingzi pluton from Chifeng area, southern Inner Mongolia, in China are studied to reveal their petrogenetic relationship with the host pluton. Furthermore, the coeval magmatic assemblage and its petrogenesis on the northern margin of the North China craton (NCC) are studied synthetically to elucidate their tectonic setting and the implications for the destruction of the NCC. Zircon U‐Pb dating reveals that the mafic enclaves formed at 230.4 ± 2.2 Ma, which is similar to the age of the host pluton. The most basic mafic enclaves belong to weak alkaline rocks, and they display rare earth element (REE) and trace element normalized patterns and trace element compositions similar to those of ocean island basalt (OIB). In addition, they have positive ∊_Nd(t) values (+3.84 to +4.94) similar to those of the Cenozoic basalts on the northern margin of the NCC. All of these geochemical characteristics suggest that the basic mafic rocks originated from the asthenosphere. Petrological and geochemical studies suggest that the Jiefangyingzi pluton and the intermediate mafic enclaves were formed by the mixing of the asthenosphere‐derived and crust‐derived magmas in different degrees. The Mid‐Late Triassic magmatic rocks on the northern margin of the NCC could be classified into three assemblages according to their geochemical compositions: alkaline series, weak alkaline–sub‐alkaline series and sub‐alkaline series rocks. Petrogenetic analyses suggest that the upwelling of the asthenosphere played an important role in the formation of these Mid‐Late Triassic magmatic rocks. Basing on an analysis of regional geological data, we suggest that the northern margin of the NCC underwent destruction due to the upwelling of the asthenosphere during the Mid‐Late Triassic, which was induced by the delamination of the root of the collisional orogeny between Sino‐Korean and Siberian paleoplates in Late Permian.

中文翻译：

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三叠纪中晚期华北克拉通北缘的破坏：来自内蒙古南部赤峰地区解放鹰子花岗岩体的软流圈衍生的黑铁质飞地的证据

研究了内蒙古南部赤峰地区晚三叠世解放英子岩体中镁铁质飞地的岩石学，地球年代学和地球化学，揭示了它们与宿主岩体的成因关系。此外，对华北克拉通北缘的近代岩浆组合及其成岩作用进行了综合研究，以阐明其构造背景及其对NCC破坏的意义。锆石U-Pb测年表明，镁铁质飞地形成于230.4±2.2 Ma，与宿主岩体的年龄相似。最基本的镁铁质飞地属于弱碱性岩石，它们显示的稀土元素（REE）和痕量元素归一化模式以及与海洋岛屿玄武岩（OIB）相似的痕量元素组成。另外，他们有积极的∊ _Nd（t）值（+3.84至+4.94），类似于NCC北缘的新生代玄武岩。所有这些地球化学特征表明，基本的镁铁质岩石起源于软流圈。岩石学和地球化学研究表明，解放英子岩体和中性镁铁质飞地是由软流圈和地壳衍生的岩浆不同程度地混合形成的。NCC北缘的中晚三叠世岩浆岩可根据其地球化学组成分为三类：碱性系列，弱碱性-亚碱性系列和亚碱性系列岩石。岩石成因分析表明，软流圈的上升对这些晚三叠世岩浆岩的形成起了重要作用。