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首页> 外文期刊>GSA Bulletin >Geochemistry of Neoarchean (ca. 2.55-2.50 Ga) volcanic and ophiolitic rocks in the Wutaishan greenstone belt, central orogenic belt, North China craton: Implications for geodynamic setting and continental growth
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Geochemistry of Neoarchean (ca. 2.55-2.50 Ga) volcanic and ophiolitic rocks in the Wutaishan greenstone belt, central orogenic belt, North China craton: Implications for geodynamic setting and continental growth

机译：华北克拉通五台山绿岩带，中部造山带的新太古代（约2.55-2.50 Ga）火山岩和蛇绿岩的地球化学：对地球动力学背景和大陆生长的影响

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摘要

Geological investigation of the Neoarchean (2.55–2.50 Ga) Wutaishan greenstone belt in the central orogenic belt of the North China craton has provided new information on the geodynamic origin of this belt and its mineral deposits. Structural, geochronological, and geochemical characteristics of the Wutaishan greenstone belt suggest that it formed in a forearc tectonic environment at ca. 2.55 Ga and accreted to the Eastern continental block at ca. 2.50 Ga. A ridge subduction model is proposed to explain several unique geological features of the Wutaishan greenstone belt, such as the generation of dunites and chromitite-hosting harzburgites with U-shaped rare earth element (REE) patterns, formation of volcanogenic massive sulphides (VMS) and banded iron formations (BIF), extrusion of mafic to felsic volcanic rocks, and intrusion of tonalite-trondhjemite-granodiorite plutons (TTG). Anomalously high geothermal gradients in the subarc mantle-wedge beneath the Wutaishan forearc may have increased its buoyancy, resulting in its accretion to the continental crust. We propose that ridge subduction also played an important role in the growth of Archean continental crust. In this model, the origin of Archean TTG is genetically linked to eclogites through partial melting of accreted and/or underplated oceanic plateaus and normal oceanic crust under amphibolite to eclogite metamorphic conditions by upwelling of an anomalously hot asthenospheric mantle window resulting from ridge subduction. TTG suites intruding Archean accretionary complexes formed the nuclei of intra-oceanic island arcs; subsequent juxtaposition of these arcs resulted in the lateral growth of Archean continental crust.
机译：华北克拉通中部造山带新太古代（2.55-2.50 Ga）五台山绿岩带的地质调查提供了有关地球动力学的新信息。该带及其矿床的起源。五台山绿岩 带的结构，年代学， 和地球化学特征表明它是在大约前缘构造环境 中形成的。约2.55 Ga，并在约2时向东部大陆块 增生。 2.50 Ga。提出了一个脊俯冲模型来解释五台山绿岩带的几个独特的地质特征，例如二重晶石的生成和铬铁矿的沉积 sup>具有U形稀土元素（REE）模式的火山岩， 形成的火山性大块硫化物（VMS）和带状 铁形成（BIF），铁镁质向长素体挤压 火山岩，以及斜长石-长白云母-碎屑闪长岩体的侵入 （TTG）。五台山前缘下的弧形地幔楔 的异常高的地热梯度可能增加了其浮力， 导致了其对大陆壳的增加。我们建议 脊俯冲在太古宙大陆壳的生长 中也起着重要作用。在此模型中，太古宙TTG的起源通过增生和/或未沉积的海洋高原和正常洋壳的部分融化 遗传连接到榴辉岩沿隆起俯冲导致的异常热的软流圈地幔窗口 隆升，在角闪石到榴辉岩变质条件下形成。 TTG套件侵入Archean 增生复合体，形成了大洋内部岛屿 弧的核。这些弧的随后并置导致太古宙大陆壳的 侧向生长。

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  • 来源
    《GSA Bulletin》 |2005年第12期|1387-1399|共13页
  • 作者

    Ali Polat; Timothy Kusky; Jianghai Li; Brian Fryer; Robert Kerrich; Katie Patrick;

  • 作者单位

    Department of Earth Sciences, University of Windsor, Windsor, Ontario N9B 3P4, Canada;

    Department of Earth and Atmospheric Sciences, Saint Louis University, St. Louis, Missouri 63103, USA;

    Department of Geology, Peking University, Beijing 100871, China;

    Department of Earth Sciences, University of Windsor, Windsor, Ontario N9B 3P4, Canada and Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4, Canada;

    Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada;

    Department of Earth Sciences, University of Windsor, Windsor, Ontario N9B 3P4, Canada;

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