Abstract Dyke swarms formed in extensional settings and are important proxies to track mantle source characteristics as well as continent and supercontinent break-up. The late Paleoproterozoic mafic-intermediate dykes in the Xiaoqinling region, southern margin of the North China Craton (NCC), provide a window to investigate the late Paleoproterozoic magma sources and tectonic evolution. Although many studies have been conducted on this region, the timing of late Paleoproterozoic extension and tectonic setting remain debated. Here we present results from LA-ICP-MS zircon U-Pb geochronology, Lu-Hf isotopic analyses and geochemistry of these dykes, together with an evaluation of the published geochronological and geochemical data for the regional dyke activity. The zircon U-Pb data show emplacement ages of 1751–1841 Ma for the dykes and compiled age data indicate widespread late Paleoproterozoic dyke emplacement during 1.85–1.75 Ga, with the majority of formed at 1.84–1.80 Ga. The geochemical characteristics, along with zircon eHf(t) values (showing two distinct ranges: 0.7–7.4 and −5.1–0), indicate multiple magma sources for the 1.84–1.80 Ga dykes from asthenosphere and depleted subcontinental lithosphere sources followed by interaction and mixing with continental crust. Geochemically, the dykes are enriched in Ba, K and P and depleted in Nb, Ta and Sr. The geological and geochemical features of these dykes are consistent with their formation within a post-collisional extension setting. We also evaluate the significance of these dykes in terms of paleogeographic correlations within the Columbia supercontinent through correlations with the North China Craton, Indian Shield and West Australia Craton.

中文翻译：

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华北克拉通南缘晚古元古代基性-中岩脉：对岩浆源和哥伦比亚重建的启示

摘要 堤防群在伸展环境中形成，是追踪地幔源特征以及大陆和超大陆分裂的重要代表。华北克拉通南缘小秦岭地区晚古元古代基性中脉岩脉为研究晚古元古代岩浆来源和构造演化提供了一个窗口。尽管对该地区进行了许多研究，但关于晚古元古代伸展和构造环境的时间仍然存在争议。在这里，我们展示了这些岩脉的 LA-ICP-MS 锆石 U-Pb 年代学、Lu-Hf 同位素分析和地球化学的结果，以及对已发表的区域岩脉活动的年代学和地球化学数据的评估。锆石 U-Pb 数据显示岩脉的侵位年龄为 1751-1841 Ma，汇编年龄数据表明晚古元古代岩脉在 1.85-1.75 Ga 期间广泛侵位，大部分形成于 1.84-1.80 Ga。地球化学特征，以及锆石 eHf(t) 值（显示两个不同的范围：0.7-7.4 和 -5.1-0）表明 1.84-1.80 Ga 岩脉的多个岩浆来源来自软流圈和枯竭的次大陆岩石圈来源，随后与大陆地壳相互作用和混合。在地球化学上，这些岩脉富含 Ba、K 和 P，而缺乏 Nb、Ta 和 Sr。这些岩脉的地质和地球化学特征与其在碰撞后伸展环境中的形成是一致的。