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首页> 外文期刊>Brazilian Journal of Geology >The Barreiro suite in the central Ribeira Belt (SE-Brazil): a late Tonian tholeiitic intraplate magmatic event in the distal passive margin of the S?o Francisco Paleocontinent
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The Barreiro suite in the central Ribeira Belt (SE-Brazil): a late Tonian tholeiitic intraplate magmatic event in the distal passive margin of the S?o Francisco Paleocontinent

机译：中央里贝拉带（巴西东南部）的Barreiro套件：在S？o Francisco古大陆的远端被动边缘发生的晚Tonian冲蚀性板内岩浆事件

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摘要

New geochemical, U-Pb, Lu-Hf and Sr-Nd data from the Barreiro Suite metabasites in comparison with enclaves within the distal Andrelandia Group and the orthogranulites of the Juiz de Fora Complex are presented. Geochemical data suggest intraplate setting, with high and low-TiO 2 , TDM Nd ages between 1.80 and 1.41 Ga, negative ΕNd t and ( 87 Sr/ 86 Sr)i between 0.714 and 0.747. Results contrast with part of the Juiz de Fora Complex enclaves, with island arc tholeiites- calcalkaline basalts (IAT-CAB) geochemical signatures, TDM Nd ages between 2.58 and 2.16 Ga, positive ΕNd t values and (87Sr/86Sr) i between 0.700 and 0.712. U-Pb data for the Barreiro Suite yielded a crystallization age of 766 ± 13 Ma and a metamorphic overprint of 619 ± 6 Ma. The results indicate three episodes of mafic magmatism in the Occidental terrane of the Ribeira Belt. The two older episodes are related to Rhyacian arc evolution (ca. 2.2 to 2.1 Ga) and to the Statherian (ca. 1.7 Ga) tectonics, and occur only within the Juiz de Fora Complex, while the younger ca. 766 Ma episode constrains the timing of distal passive margin evolution. An important implication is that these late Tonian metabasic rocks could have been a source of detrital zircons for the sedimentation along the distal Andrelandia basin.
机译：与远端Andrelandia组内的飞地和Juiz de Fora Complex的原粒岩相比，Barreiro Suite阶地的新地球化学，U-Pb，Lu-Hf和Sr-Nd数据得以呈现。地球化学数据表明板内凝固，高和低TiO 2的TDM Nd年龄在1.80和1.41 Ga之间，负ＥＮd ｔ和（87 Sr / 86 Sr）i在0.714和0.747之间。结果与Juiz de Fora复杂飞地的一部分形成对比，岛上的弧形辉绿岩-钙碱性玄武岩（IAT-CAB）地球化学特征，TDM Nd年龄在2.58至2.16 Ga之间，正ＥＮｄｔ值和（87Sr / 86Sr）i在0.700至200之间0.712。 Barreiro Suite的U-Pb数据产生了766±13 Ma的结晶年龄和619±6 Ma的变质叠印。结果表明，在Ribeira带的西方地层中发生了3次镁铁质岩浆作用。这两个较早的事件与Rhyacian弧演化（约2.2至2.1 Ga）和Statherian（约1.7 Ga）构造有关，仅在Juiz de Fora Complex内部发生，而较年轻的约有一次。 766 Ma发作限制了远端被动切缘发展的时机。一个重要的含义是，这些晚期的Tonian准生代岩石可能是碎屑锆石的来源，用于沿Andrelandia盆地的远端沉积。

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