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Early Paleozoic intracontinental orogeny and post-orogenic extension in the South China Block: Insights from volcanic rocks

机译:华南地块的早古生代陆内造山运动和造山后扩展:来自火山岩的见解

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摘要

The early Paleozoic orogeny represents the first extensive Phanerozoic tectono-thermal event in the South China Block (SCB). Two distinct orogeny models, subduction-collision orogeny and intracontinental orogeny, have been proposed, and one of the key controversies is the nature and the tectonic implications of the associated early Paleozoic volcanic rocks in the SCB, which have not yet been systematically investigated. Zircon U-Pb dating results show that these volcanic rocks formed at 445-435 Ma, coeval with large-scale intrusive magmatism (446-420 Ma). The felsic volcanic rocks, which include the Mashan and Hekou dacites and rhyolites, show high SiO2, low MgO and low Fe2O3 contents. Whole rock trace-element and isotopic compositions of the felsic volcanic rocks suggest that they were generated by partial melting of a Paleoproterozoic crustal component. The mafic volcanic rocks are represented by the Chayuanshan basalts, which are characterized by low SiO2, high MgO, Cr and Ni contents, enrichment in LILEs and depletion in HFSEs. The low Nb/La ratios, high Th/Yb ratios and negative whole-rock epsilon(Nd)(t) values suggest that the basalts were derived from partial melting of a metasomatized subcontinental lithospheric mantle (SCLM). The "subduction signature" (calc-alkaline affinity, enriched LILEs and depleted HFSEs) of the Chayuanshan basalts was supposed to be inherited from the source and it didn't reflect their generation in a subduction-related arc setting. Asthenospheric mantle upwelling and basaltic magma underplating may have been responsible for the partial melting of the crust and the metasomatized SCLM, which produced the Hekou and Mashan dacites and rhyolites and Chayuanshan basalts, respectively. Activation of the pre-existing suture zones, asthenospheric mantle upwelling and extensive partial melting of the crust caused the intensive magmatism of the SCB in early Paleozoic. (C) 2016 Elsevier Ltd. All rights reserved.
机译:早古生代造山运动是华南区块(SCB)中的首个广泛的生代构造热事件。已经提出了两种不同的造山模式,即俯冲-碰撞造山和陆内造山,其中主要的争议之一是SCB中相关的早古生代火山岩的性质和构造意义,尚未进行系统的研究。锆石U-Pb测年结果​​表明,这些火山岩形成于445-435 Ma,与大规模侵入岩浆作用(446-420 Ma)同时存在。包括马山和河口的辉绿岩和流纹岩在内的长英质火山岩具有较高的SiO2,较低的MgO和较低的Fe2O3含量。长英质火山岩的完整岩石痕量元素和同位素组成表明,它们是通过古元古代地壳组分的部分熔融而产生的。镁铁质火山岩以茶园山玄武岩为代表,其特征是SiO2低,MgO,Cr和Ni含量高,LILE富集和HFSE耗竭。低的Nb / La比,高的Th / Yb比和负的全岩石epsilon(Nd)(t)值表明,玄武岩是由交代化的亚大陆岩石圈地幔(SCLM)的部分熔融而得的。茶园山玄武岩的“俯冲特征”(钙碱性亲和力,富集的LILE和贫化的HFSE)应该是从源头继承而来的,并且没有反映出它们在俯冲相关弧环境中的产生。软流圈地幔上升流和玄武岩浆岩床底可能是造成地壳和交代的SCLM部分融化的原因,这分别产生了河口和马山的辉石和流纹岩和茶园山的玄武岩。先前存在的缝合带的活化,软流圈地幔上涌和地壳的广泛部分熔融,引起了早古生代SCB的强烈岩浆作用。 (C)2016 Elsevier Ltd.保留所有权利。

著录项

  • 来源
    《Journal of Asian earth sciences》 |2017年第15期|24-42|共19页
  • 作者单位

    Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Jiangsu, Peoples R China;

    Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Jiangsu, Peoples R China;

    Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Jiangsu, Peoples R China;

    Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Jiangsu, Peoples R China|Guilin Univ Technol, Coll Earth Sci, Guangxi Key Lab Hidden Metall Ore Deposits Explor, Guilin 541004, Peoples R China;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Early Paleozoic volcanic rocks; Intracontinental orogeny; Post-orogenic extension; South China Block;

    机译:早古生代火山岩陆内造山作用造山后扩张华南地块;
  • 入库时间 2022-08-18 03:38:13

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