A Long-Lived Accretionary Process during the Amalgamation of the North China Craton: Insights from Neoarchean–Paleoproterozoic Polyphase Magmatism in the Lüliang Complex
A Long-Lived Accretionary Process during the Amalgamation of the North China Craton: Insights from Neoarchean–Paleoproterozoic Polyphase Magmatism in the Lüliang Complex
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DOI：
10.2113/2023/lithosphere_2023_229
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发表时间：
2023-11
期刊：
影响因子：
2.4
通讯作者：
Xinyuan Yu;Jian Zhang;Jin Liu;C. Yin;Ying Chen;Minjie Guo;J. Qian;Peng Gao;Changquan Cheng-Changqu
中科院分区：
文献类型：
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作者：
Xinyuan Yu;Jian Zhang;Jin Liu;C. Yin;Ying Chen;Minjie Guo;J. Qian;Peng Gao;Changquan Cheng-Changqu
关于华北板块最终合并的时间一直存在争议，认为是发生在新太古代还是古元古代。一个主要的争论点是是否存在一个长期的俯冲持续通过新太古代到古元古代。吕梁杂岩包含多期岩浆活动，因此代表了解决这一争议的最可行区域。本文对代表性花岗岩类进行了年代学和地球化学分析。二次离子质谱U-Pb测年结果表明，花岗岩类有4个不同的侵位年龄，分别为2531 ± 4，2189 - 2173，2027 ± 25和1852 ± 41Ma。值得注意的是，2531 Ma花岗质片麻岩是首次在该地区。根据岩石地球化学特征，花岗岩类可分为两类。2531和2027 Ma群具有I型特征，2189 - 2173和1852 Ma群具有A型地球化学亲和力。两个I型岩石群均表现出富Rb、贫Nb、Ta和Ti、中等分馏的REE配分模式、显著的负Eu异常、低Sr/Y比值和正ε Hf（t）（分别为+3.51~+5.53和+5.59~+7.32），表明它们是由年轻镁铁质地壳部分熔融形成的。2189 - 2173 Ma的花岗岩类属于A2型，可能是弧后长英质岩石部分熔融的产物; 1852 Ma的花岗岩类属于A1型，可能是碰撞后镁铁质-中性岩石部分熔融的产物。根据华北造山带A型花岗质岩浆活动和~1950Ma峰期变质作用的记录，我们认为一个长期的俯冲过程（2531-1950Ma）可以解释华北造山带的地质现象。东部和西部块体之间的俯冲作用可能始于~2531 Ma，随后是一个长期的俯冲作用。这两个块体最终在~1950 Ma相互碰撞形成华北板块，在~1852 Ma引发碰撞后折返和部分熔融。
There has been a long debate regarding the timing of the final amalgamation of the North China Craton, which is considered to have occurred either during the Neoarchean or Paleoproterozoic era. One major point of contention is whether there existed a long-lived subduction lasting through the Neoarchean to Paleoproterozoic. The Lüliang Complex contains multiphases of magmatism and thus represents the most viable region to address this controversy. In this study, we carried geochronological and geochemical analysis on the representative granitoids. Secondary ion mass spectrometry U–Pb dating revealed four distinct granitoid groups emplaced at 2531 ± 4, 2189–2173, 2027 ± 25, and 1852 ± 41 Ma, respectively. Notably, the 2531 Ma granitic gneiss was identified for the first time in this region. Based on the geochemical characteristics, the granitoids can be divided into two types. The 2531 and 2027 Ma groups display I-type features, while the 2189–2173 and 1852 Ma groups exhibit A-type geochemical affinities. Both I-type groups exhibit enrichment in Rb, depletion in Nb, Ta, and Ti, moderate fractionated REE patterns, substantial negative Eu anomalies, low Sr/Y ratios, and positive εHf(t) (+3.51 to +5.53 and +5.59 to +7.32, respectively), indicating that they were generated from partial melting of the juvenile mafic crust. In contrast, the 2189–2173 Ma granitoids belong to A2-type and were most likely generated by the partial melting of felsic rocks in the back-arc region, while the 1852 Ma granitoids belong to A1-type and were most possibly the result of partial melting of mafic-intermediate rocks during the post-collisional stage. Based on the records of A-type granitic magmatism and the ~1950 Ma peak metamorphism throughout the Trans-North China Orogen, we propose that a long-lived subduction process (2531–1950 Ma) can mostly explain the existing geological phenomena. It is likely that the subduction between the Eastern and Western Blocks should have commenced at ~2531 Ma, followed by a long-lived subduction. The two blocks ultimately collided with each other to form the North China Craton at ~1950 Ma, which triggered post-collisional exhumation and partial melting at ~1852 Ma.