The northern margin of the North China Craton (NCC) contains widespread Permian magmatic rocks, but the origin of these rocks remains controversial. This uncertainty hampers us from better understanding of tectonic framework and evolution of the eastern Paleo-Asian Ocean, particularly with respect to its final-stage subduction and closure time. To address these questions, this study presents petrological, zircon U-Pb geochronological, whole-rock geochemical and in situ zircon Hf isotopic data for these Permian mafic intrusions in the northern margin of the NCC. Precise zircon U-Pb dating results indicate that these mafic intrusions were emplaced in the Middle Permian (ca. 260 Ma). Geochemically, the studied mafic intrusions have high MgO and transition metals element contents, with high Mg^# values, indicating a mantle origin. These mafic intrusions are characterized by enrichments in large ion lithophile elements (LILEs; e.g., Rb, Ba, and K) and light rare earth elements (LREEs), and depletions in high field strength elements (HFSEs; e.g., Nb, Ta, and Ti) and heavy rare earth elements (HREEs), indicating that they were formed in a subduction-related setting. These geochemical features, together with zircon ∊_Hf(t) values (–1.1 to +11.2), indicate that their parental magmas were derived from partial melting of heterogeneous mantle wedge metasomatized by subduction-related fluids, with the contributions of slab sediments. The studied mafic intrusions also show wide range of major and trace elements contents, and variable Mg^# values, Eu and Sr anomalies, suggesting that their parental magmas had undergone variable degrees of fractional crystallization. Together with the E–W trending Permian continental arc along the northern margin of the NCC, we confirm that the generation of the Middle Permian mafic intrusions was related to southward subduction of the Paleo-Asian oceanic lithosphere beneath the NCC and the Paleo-Asian Ocean had not closed prior to the Middle Permian.

中文翻译：

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东古亚洲洋末期南向俯冲：来自华北克拉通北缘中二叠统镁铁质侵入体的证据

华北克拉通（NCC）北缘含有广泛的二叠纪岩浆岩，但这些岩石的成因仍有争议。这种不确定性阻碍了我们更好地了解东古亚洲洋的构造框架和演化，特别是在其最后阶段俯冲和闭合时间方面。为了解决这些问题，本研究提供了华北克拉通北缘这些二叠纪镁铁质侵入体的岩石学、锆石 U-Pb 年代学、全岩地球化学和原位锆石 Hf 同位素数据。精确的锆石 U-Pb 测年结果表明，这些镁铁质侵入体位于中二叠纪（约 260 Ma）。地球化学上，所研究的镁铁质侵入体具有较高的 MgO 和过渡金属元素含量，其中 Mg ^#值，表明地幔起源。这些镁铁质侵入体的特点是富集大离子亲石元素（LILEs，例如 Rb、Ba 和 K）和轻稀土元素（LREEs），而贫化高场强元素（HFSEs，例如 Nb、Ta 和Ti）和重稀土元素（HREEs），表明它们是在与俯冲相关的环境中形成的。这些地球化学特征，连同锆石∊ _Hf (t) 值（–1.1 到 +11.2），表明它们的母岩浆来源于俯冲相关流体交代的非均质地幔楔的部分熔融，其中板片沉积物的贡献。所研究的镁铁质侵入体还显示出广泛的主量和微量元素含量，以及可变的 Mg ^#值，Eu 和 Sr 异常，表明它们的母岩浆经历了不同程度的分级结晶。结合华北克拉通北缘的东西向二叠纪大陆弧，我们证实中二叠纪镁铁质侵入体的产生与华北克拉通下方古亚洲大洋岩石圈和古亚洲洋向南俯冲有关。在中二叠纪之前没有关闭。