The North Qilian Orogenic Belt is surrounded by the Tarim Craton to the NW and the North China Craton to the NE. The Precambrian continental crust remnants that are distributed in the North Qilian Orogenic Belt are termed the North Qilian Block (NQB), and their tectonic evolution has profound implications for the evolution of the Columbia Supercontinent. Here we present major- and trace-element and Sr–Nd–Hf isotope data for (meta-) basalts from the Beidahe Group (BDHG) and Zhulongguan Group (ZLGG) in the western North Qilian Orogenic Belt, to investigate the tectonic evolution of the NQB during the Proterozoic Eon. The protoliths of Palaeoproterozoic amphibole gneisses and plagioclase amphibolites from the BDHG are calc-alkaline series basalts. These metabasalts show island-arc-basalt affinities with variable Nd and Hf isotopes (ϵNd(t) = −5.0–0.6 and 2.7–4.3; ϵHf(t) = −14.2–2.0 and 6.9–8.8) and were generated by partial melting of the asthenospheric mantle that was metasomatized by aqueous fluid and sediment melt in a continental-arc setting. The early Mesoproterozoic ZLGG basalts show features of shoshonite-series basalts and are geochemically similar to ocean-island basalts. These basalts show variable (87Sr/86Sr)i, ϵNd(t) and ϵHf(t) values of 0.70464–0.70699, −1–2.6 and −1.5–5.7, and are products of mantle plume magmatism that participated with subducted oceanic crust in an intracontinental rift setting. This study suggests that the NQB underwent tectonic evolution from palaeo-oceanic subduction to intracontinental rifting during the Palaeoproterozoic–Mesoproterozoic eras. Furthermore, the above tectonomagmatic events were in response to convergence–splitting events of the Columbia Supercontinent during the Palaeoproterozoic–Mesoproterozoic eras.

中文翻译：

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北祁连造山带（变）玄武岩的岩石成因：对北祁连地块古元古代—中元古代构造演化的启示

北祁连造山带西北为塔里木克拉通，东北为华北克拉通。分布于北祁连造山带的前寒武纪大陆地壳残余物被称为北祁连陆块（NQB），其构造演化对哥伦比亚超大陆的演化具有深远的影响。在这里，我们提供北祁连造山带西部北大河群 (BDHG) 和竹龙关群 (ZLGG) 玄武岩的主量元素和微量元素以及 Sr-Nd-Hf 同位素数据，以研究北祁连造山带西部的构造演化。元古代的NQB。BDHG古元古代闪石片麻岩和斜长角闪岩的原岩为钙碱性系列玄武岩。这些变玄武岩显示出与可变 Nd 和 Hf 同位素的岛弧玄武岩亲和力（ε钕(吨) = -5.0–0.6 和 2.7–4.3；ε氢氟酸(吨) = -14.2-2.0 和 6.9-8.8) 并且是由软流圈地幔的部分熔融产生的，该地幔在大陆弧环境中被含水流体和沉积物熔体交代。早中元古代ZLGG玄武岩具有钾玄武岩系列玄武岩的特征，在地球化学上与海岛玄武岩相似。这些玄武岩显示变量 (87锶/86锶）一世,ε钕(吨） 和ε氢氟酸(吨) 值为 0.70464-0.70699、-1-2.6 和 -1.5-5.7，是地幔柱岩浆作用的产物，在陆内裂谷环境中参与俯冲洋壳。该研究表明，NQB在古元古代-中元古代经历了从古洋俯冲到陆内裂谷的构造演化。此外，上述构造岩浆事件是对古元古代—中元古代哥伦比亚超大陆辐合分裂事件的反应。