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首页> 外文期刊>Journal of Asian earth sciences >Geochronology and geochemistry of Permian bimodal volcanic rocks from central Inner Mongolia, China: Implications for the late Palaeozoic tectonic evolution of the south-eastern Central Asian Orogenic Belt
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Geochronology and geochemistry of Permian bimodal volcanic rocks from central Inner Mongolia, China: Implications for the late Palaeozoic tectonic evolution of the south-eastern Central Asian Orogenic Belt

机译：中国内蒙古中部二叠纪双峰火山岩的年代学和地球化学：对中亚东南部造山带东南部晚古生代构造演化的启示

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摘要

Zircon U-Pb ages, geochemical data and Sr-Nd isotopic data are presented for volcanic rocks from the lower Permian Dashizhai Formation. These rocks are widely distributed in the south-eastern Central Asian Orogenic Belt in central Inner Mongolia, China. The volcanic rocks mainly consist of basaltic andesite and rhyolite, subordinate dacite and local andesite, and exhibit bimodal geochemical features. The results of zircon U-Pb dating indicate that the volcanic rocks formed during the early Permian (292279 Ma). The mafic volcanic rocks belong to low-K tholeiitic to medium-K talc-alkaline series. These mafic volcanic rocks are also characterised by moderately enriched light rare earth element (LREE) patterns; high abundances of Th, U, Zr and Hf; negative Nb, Ta and Ti anomalies; initial Sr-87/(86) Sr ratios of 0.70514-0.70623; and positive epsilon(Nd)(t) values (+1.9 to +3.8). These features indicate that the mafic volcanic rocks were likely derived from the high-percentage partial melting of subduction-related metasomatised asthenospheric mantle. The felsic rocks show an A-type affinity, with enrichments in alkalis, Th, U and LREEs. The felsic rocks are depleted in Ba, Sr, Nb, Ta and Ti and exhibit moderately LREE-enriched patterns (La-N/Yb-N = 2.09-6.45) and strongly negative Eu anomalies (Eu/Eu* = 0.04-0.25). These features, along with the positive cNd(t) values (+2.6 to +7.7) and young T-DM2 ages (T-DM2 = 435-916 Ma), indicate that the felsic rocks Were likely derived from a juvenile crustal source that mainly consisted of juvenile mid-ocean ridge basalt-related rocks. The volcanic association in this study and in previously published work widely distributed in central Inner Mongolia. The observations in this study suggest that the lower Permian volcanic rocks formed in an identical tectonic environment. The regional geological data indicate that the bimodal volcanic rocks from the lower Permian Dashizhai Formation in the study area formed in an extensional setting that was likely related to post-collisional delamination. (C) 2017 Elsevier Ltd. All rights reserved.
机译：给出了下二叠统大石寨组火山岩的锆石U-Pb年龄，地球化学数据和Sr-Nd同位素数据。这些岩石广泛分布在中国内蒙古中部的东南中亚造山带中。火山岩主要由玄武质安山岩和流纹岩，下属菱镁矿和局部安山岩组成，并表现出双峰地球化学特征。锆石U-Pb测年的结果表明，火山岩在二叠纪早期（292279 Ma）形成。镁铁质火山岩属于低钾向中钾滑石-碱性系列。这些镁铁质火山岩的特征还在于中等程度富集的轻稀土元素（LREE）模式。 Th，U，Zr和Hf的丰度很高； Nb，Ta和Ti负异常;初始Sr-87 /（86）Sr比为0.70514-0.70623;和正epsilon（Nd）（t）值（+1.9至+3.8）。这些特征表明，镁铁质火山岩可能来自俯冲相关变质流软流圈地幔的高比例部分熔融。长英质岩石表现出A型亲和力，富含碱，Th，U和LREEs。长英质岩石贫化了Ba，Sr，Nb，Ta和Ti，并表现出中等程度的LREE富集模式（La-N / Yb-N = 2.09-6.45）和强烈的Eu负异常（Eu / Eu * = 0.04-0.25） 。这些特征，加上正的cNd（t）值（+2.6至+7.7）和年轻的T-DM2年龄（T-DM2 = 435-916 Ma），表明长英质岩石很可能来自于幼年的地壳来源，主要由与洋中脊玄武岩有关的岩石组成。这项研究和以前发表的工作中的火山协会广泛分布在内蒙古中部。这项研究的观察结果表明，下二叠纪火山岩是在相同的构造环境中形成的。区域地质数据表明，研究区下二叠统大石寨组的双峰火山岩形成于可能与碰撞后分层有关的伸展环境。 （C）2017 Elsevier Ltd.保留所有权利。

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  • 来源
    《Journal of Asian earth sciences》 |2017年第3期|370-389|共20页
  • 作者

    Zhang Zhicheng; Chen Yan; Li Ke; Li Jianfeng; Yang Jinfu; Qian Xiaoyan;

  • 作者单位

    Peking Univ, MOE Key Lab Orogen Belts & Crustal Evolut, Beijing 100871, Peoples R China|Peking Univ, Sch Earth & Space Sci, Beijing 100871, Peoples R China|Peking Univ, Room 3307,Yifu 2 Bldg,5 Yiheyuan Rd, Beijing 100871, Peoples R China;

    Peking Univ, MOE Key Lab Orogen Belts & Crustal Evolut, Beijing 100871, Peoples R China|Peking Univ, Sch Earth & Space Sci, Beijing 100871, Peoples R China;

    Chengdu Univ Technol, Coll Earth Sci, Chengdu 610059, Peoples R China;

    Chinese Acad Geol Sci, Inst Geomech, Key Lab Paleomagnetism & Tecton Reconstruct, Minist Land & Resources, Beijing 100871, Peoples R China;

    Peking Univ, MOE Key Lab Orogen Belts & Crustal Evolut, Beijing 100871, Peoples R China|Peking Univ, Sch Earth & Space Sci, Beijing 100871, Peoples R China;

    Peking Univ, MOE Key Lab Orogen Belts & Crustal Evolut, Beijing 100871, Peoples R China|Peking Univ, Sch Earth & Space Sci, Beijing 100871, Peoples R China;

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

    Zircon U-Pb dating; Early Permian; Geochemistry; Dashizhai Formation; Central Inner Mongolia; Tectonic evolution;

    机译：锆石U-Pb测年;早二叠世;地球化学;大石寨组;内蒙古中部;构造演化;

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