Paleoproterozoic multiple magmatic-metamorphic events in the Dunhuang Block, eastern Tarim Craton: Implications for assembly of the Columbia supercontinent
Paleoproterozoic multiple magmatic-metamorphic events in the Dunhuang Block, eastern Tarim Craton: Implications for assembly of the Columbia supercontinent
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DOI：
10.1016/j.precamres.2020.105949
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发表时间：
2020-12
影响因子：
3.8
通讯作者：
Pei Lv;ShengyaoYu;Yin‐biao Peng;Jian Zhang;Weiming Xie;Xingzhou Jiang;Xiangyu Gao;Wentao Ji-Wentao
中科院分区：
文献类型：
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作者：
Pei Lv;ShengyaoYu;Yin‐biao Peng;Jian Zhang;Weiming Xie;Xingzhou Jiang;Xiangyu Gao;Wentao Ji-Wentao
敦煌地块的演化与哥伦比亚超大陆的组装是不好的约束。岩浆岩和变质岩的地球化学成分和时间演化可能包含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。本文对敦煌地块英云闪长质片麻岩、碳酸盐岩、花岗质脉岩、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、Hf同位素研究。结果表明，英云闪长质片麻岩起源于3.67Ga增厚的洋坪壳或岛弧壳的部分熔融，记录了古元古代（2.02 ~ 1.96Ga）重要的俯冲-碰撞造山作用。1.94Ga碳酸岩脉和1.85Ga花岗岩脉分别由大理岩和中-新太古代基底岩石部分熔融形成。它们都形成于后碰撞环境。1.82Ga的镁铁质麻粒岩记录了高压麻粒岩相变质和中低压麻粒岩相变质叠加，显示了顺时针的P-T轨迹，反映了碰撞造山环境。1.76Ga的A型花岗岩是新太古代地壳改造的产物，可能与后碰撞事件有关。结合前人的研究，我们将敦煌地块划分为两个古元古代造山带：2.00- 1.96Ga的南造山带和1.85- 1.80Ga的北造山带。根据这两个造山带与哥伦比亚造山带的耦合关系，我们认为敦煌地块与哥伦比亚超大陆的组装有关。
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.