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首页> 外文期刊>Journal of geodynamics >Oceanic plateau accretion onto the northwestern margin of the Yilgarn Craton, Western Australia: implications for a mantle plume event at ca. 2.0 Ga
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Oceanic plateau accretion onto the northwestern margin of the Yilgarn Craton, Western Australia: implications for a mantle plume event at ca. 2.0 Ga

机译：西澳大利亚Yilgarn Craton西北边缘的海洋高原堆积物：对约瑟夫岛地幔羽事件的影响。 2.0 Ga

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摘要

The 2.0 Ga Bryah Basin (Group) is one of a series of Palaeoproterozoic basins in the eastern Capricorn Orogen, a major tectonic unit between the Archaean Pilbara and Yilgarn Cratons of Western Australia. The Narracoota Formation forms the bulk of the Bryah Group and consists of ultramafic and mafic schist and metabasaltic hyaloclastites, sheeted dykes and a layered mafic-ultramafic complex, collectively referred to as metabasites, because they are generally metamorphosed to greenschist facies. Chemically these rocks correspond to komatiites, high-Mg basalts and tholeiites. Previous interpretations have purported that these rocks represent rift-related volcanics, ophiolites and mid-ocean ridge settings. In this contribution, I show that the Narracoota Formation metabasites were likely part of an ancient oceanic plateau, created by a 2.0 Ga mantle plume. Geochemical data (eg REE patterns) indicate that the metabasites are identical to modern oceanic plateaux. The presence of erogenic gold lodes further supports the oceanic plateau model. During the 1.96 Ga Glenburgh Orogeny, which brought together an Andean-style magmatic arc (southern Gascoyne Complex) and the northwestern margin of the Yilgarn Craton, the Narracoota oceanic plateau was accreted onto the Yilgarn Craton. The 1.8 Ga Capricorn Orogeny further deformed the Narracoota metabasites, resulting in the present day structural configuration.
机译：2.0 Ga Bryah盆地（群）是摩Cap座造山带东部的古元古代盆地之一，摩ri造山带是古生的Pilbara和西澳大利亚的Yilgarn Cratons之间的主要构造单元。 Narracoota组形成了Bryah组的主体，由超镁铁质和镁铁质片岩和变玄武质的透明质碎屑岩，片状岩脉和层状的镁铁质-超镁铁质复合物（统称为变质岩）组成，因为它们通常已变质为绿岩相。从化学上讲，这些岩石对应于科马铁矿，高镁玄武岩和菱铁矿。以前的解释声称这些岩石代表与裂谷有关的火山岩，蛇绿岩和中洋脊设置。在这篇文章中，我证明了纳拉库塔组变质岩可能是由2.0 Ga地幔羽形成的古代海洋高原的一部分。地球化学数据（例如REE模式）表明这些变质岩与现代海洋高原相同。致金矿的存在进一步支持了海洋高原模型。在1.96年的Ga Glenburgh造山运动中，安第斯风格的岩浆弧（南部的加斯科因复合体）和伊尔加恩克雷顿的西北边缘汇集在一起​​，纳拉库塔海洋高原被吸纳到伊尔加恩克雷顿上。 1.8 Ga摩ri座造山运动进一步使Narracoota变质岩变形，形成了当今的结构构造。

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