Abstract The evolution of the Dunhuang Block associated with the assembly of the Columbia supercontinent is poorly constrained. The geochemical composition and temporal evolution of magmatic and metamorphic rocks may hold key information regarding critical geodynamic processes that occurred during the evolution of the Dunhuang Block. In this paper, we present a systematic petrographic, geochemical, and zircon U-Pb and Hf isotopic investigation on tonalitic gneiss, carbonatite, granitic dyke, mafic granulite and A-type granite in the Dunhuang Block. The results suggest that tonalitic gneiss was derived from partial melting of a thickened oceanic plateau crust or island-arc crust at ~3.67 Ga and then it recorded an important subduction-collision orogenesis in the Paleoproterozoic (~2.02 Ga to ~1.96 Ga). The ~1.94 Ga carbonatite and ~1.85 Ga granitic dyke were formed by partial melting of marble and Meso- to Neoarchean basement rocks, respectively. Both of them were formed in post-collisional setting. The ~1.82 Ga mafic granulite recorded high-pressure granulite facies metamorphism followed by a medium–low pressure granulite facies metamorphic overprint, suggesting a clockwise P-T path and implying an environment of collisional orogenesis. The ~1.76 Ga A-type granite resulted from the reworked Neoarchean crust and was most likely related to a post-collisional episode. Combined with previous studies, we identify two Paleoproterozoic orogenic belts of the Dunhuang Block: the ~2.00–1.96 Ga South Orogen and ~1.85–1.80 Ga North Orogen. According to the coupling of these two orogenies with the Columbia orogeny, we conclude that the Dunhuang Block was associated with the assembly of the Columbia supercontinent.

中文翻译：

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塔里木克拉通东部敦煌地块古元古代多次岩浆变质事件：对哥伦比亚超大陆组装的启示

摘要 与哥伦比亚超大陆的组装相关的敦煌地块的演化受到的约束很差。岩浆和变质岩的地球化学组成和时间演化可能掌握着敦煌地块演化过程中发生的关键地球动力学过程的关键信息。在本文中，我们对敦煌地块的片麻岩、碳酸岩、花岗岩脉、镁铁质麻粒岩和 A 型花岗岩进行了系统的岩石学、地球化学和锆石 U-Pb 和 Hf 同位素研究。结果表明，色调片麻岩来源于增厚的大洋高原地壳或岛弧地壳在~3.67 Ga的部分熔融，然后在古元古代（~2.02 Ga至~1.96 Ga）记录了重要的俯冲碰撞造山作用。~1.94 Ga 碳酸岩和 ~1. 85 Ga 花岗质岩脉分别由大理岩和中至新太古代基底岩部分熔融形成。它们都是在碰撞后的环境中形成的。~1.82 Ga 基性麻粒岩记录了高压麻粒岩相变质作用，然后是中低压麻粒岩相变质叠印，表明顺时针 PT 路径并暗示碰撞造山作用的环境。~1.76 Ga A 型花岗岩是由重新加工的新太古代地壳产生的，很可能与碰撞后事件有关。结合之前的研究，我们确定了敦煌地块的两条古元古代造山带：~2.00-1.96 Ga 南造山带和~1.85-1.80 Ga 北造山带。根据这两个造山带与哥伦比亚造山带的耦合，