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Rhyacian-Orosirian tectonic history of the Juiz de Fora Complex: Evidence for an Archean crustal reservoir within an island-arc system
Geoscience Frontiers ( IF 8.5 ) Pub Date : 2021-08-25 , DOI: 10.1016/j.gsf.2021.101292
Rasec Almeida 1 , Vitalino Elizeu 1 , Henrique Bruno 1 , Samuel Moreira Bersan 1 , Lucas Eduardo de Abreu Barbosa Araujo 1 , Ivo Dussin 1 , Claudio de Morisson Valeriano 1, 2 , Carla Neto 1, 2 , Monica Heilbron 1
Affiliation  

The southern São Francisco Paleocontinent (SFP) comprises Archean nuclei and Paleoproterozoic complexes encompassing magmatic arcs juxtaposed during a Rhyacian to Orosirian orogenic event. The Juiz de Fora Complex (JFC) represents an imbricated thrust system that comprises orthogranulites with a wide compositional range formed in an intra-oceanic setting during the Siderian to the Orosirian and later accreted to the southeastern margin of the SFP. Here we report new petrological, geochemical, whole-rock Nd and Sr data, as well as zircon U–Pb ages from felsic and mafic orthogranulites from the JFC. The new data is combined with a regional compilation that enables an evaluation of the interaction between magmatism and orogenetic episodes in the context of the consolidation of São Francisco Paleocontinent during the Rhyacian–Orosirian. Pre collisional Island Arc tholeiites (IAT), Tonalites-Trondhjemites-Granodiorites (TTGs) and sanukitoid magmatism occurred from 2200 Ma to 2085 Ma. This was followed by post-collisional magmatism, which is represented by hybrid granitoids coeval with the emplacement of E-MORB basic rocks. Crustal signatures for the Rhyacian to Orosirian evolution are highlighted by the dominance of negative εNd(t) associated with Meso- to Neoarchean Nd TDM model ages as well as inherited zircon grains from the hybrid granitoids. The JFC is extensively highlighted in the literature as a primitive intra-oceanic arc, but here we propose the reworking or recycling of ancient crustal segments within the mature arc stage of the JFC, suggesting a Mesoarchean crustal source involved in the JFC evolution.



中文翻译:

Juiz de Fora 复合体的 Rhyacian-Orosirian 构造历史:岛弧系统内太古代地壳储层的证据

南圣弗朗西斯科古大陆 (SFP) 包括太古代原子核和古元古代复合体,包括在 Rhyacian 到 Orosirian 造山事件期间并列的岩浆弧。Juiz de Fora Complex (JFC) 代表了一个叠瓦状逆冲推力系统,该系统包括在 Siderian 到 Orosirian 期间在洋内环境中形成的具有广泛组成范围的正麻粒岩,后来又增加到 SFP 的东南边缘。在这里,我们报告了新的岩石学、地球化学、全岩 Nd 和 Sr 数据,以及来自 JFC 的长英质和镁铁质正麻粒岩的锆石 U-Pb 年龄。新数据与区域汇编相结合,可以在 Rhyacian-Orosirian 期间 São Francisco Paleocontinent 合并的背景下评估岩浆活动和造山事件之间的相互作用。碰撞前岛弧拉斑岩(IAT)、方长岩-长闪长岩-花岗闪长岩(TTGs)和sanukitoid岩浆作用发生在2200-2085Ma。随后是碰撞后岩浆作用,以与 E-MORB 基性岩就位同时期的混合花岗岩为代表。Rhyacian 到 Orosirian 演化的地壳特征通过负 ε 的优势突出显示Nd ( t ) 与中至新太古代 Nd T DM模型年龄以及来自杂化花岗岩的继承锆石颗粒有关。JFC 在文献中被广泛强调为原始的洋内弧,但在这里我们建议在 JFC 的成熟弧阶段内重新加工或回收古代地壳部分,表明 JFC 演化涉及中太古代地壳源。

更新日期:2021-08-26
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