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首页> 外文期刊>Anais da Academia Brasileira de Ciencias >Tectonic evolution of the southern margin of the Amazonian craton in the late Mesoproterozoic based on field relationships and zircon U-Pb geochronology
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Tectonic evolution of the southern margin of the Amazonian craton in the late Mesoproterozoic based on field relationships and zircon U-Pb geochronology

机译：基于场关系和锆石U-Pb年代学的中元古代晚期亚马孙克拉通南缘的构造演化

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New U-Pb zircon geochronological data integrated with field relationships and an airborne geophysical survey suggest that the Nova Brasilandia and Aguapeí belts are part of the same monocyclic, metaigneous and metasedimentary belt formed in the late Mesoproterozoic (1150 Ma-1110 Ma). This geological history is very similar to the within-plate origin of the Sunsás belt, in eastern Bolivia. Thus, we propose that the Nova Brasilandia, Aguapeí and Sunsás belts represent a unique geotectonic unit (here termed the Western Amazon belt) that became amalgamated at the end of the Mesoproterozoic and originated through the reactivation of a paleo-suture (Guaporé suture zone) in an intracontinental rift environment. Therefore, its geological history involves a short, complete Wilson cycle of ca. 40 Ma. Globally, this tectonic evolution may be related with the final breakup of the supercontinent Columbia. Mafic rocks and trondhjemites in the northernmost portion of the belt yielded U-Pb zircon ages ca. 1110 Ma, which dates the high-grade metamorphism and the closure of the rift. This indicates that the breakup of supercontinent Columbia was followed in short sequence by the assembly of supercontinent Rodinia at ca. 1.1-1.0 Ga and that the Western Amazon belt was formed during the accretion of the Arequipa-Antofalla basement to the Amazonian craton.
机译：新的U-Pb锆石年代学数据与野外关系和航空地球物理调查相结合，表明Nova Brasilandia和Aguapeí带属于中元古生代晚期（1150 Ma-1110 Ma）形成的同一单环，亚成岩和准沉积带。这段地质历史与玻利维亚东部的Sunsás带的板内起源非常相似。因此，我们建议新布拉斯兰迪亚带，阿瓜皮伊带和桑萨斯带代表一个独特的大地构造单元（这里称为西亚马逊带），该带在中元古界末期合并，并通过重新激活古缝合线（瓜珀雷缝合带）而形成。在大陆内部裂谷环境中。因此，其地质历史涉及一个短而完整的大约威尔逊循环。 40毫安在全球范围内，这种构造演化可能与超大陆哥伦比亚的最终破裂有关。该带最北端的镁铁质岩石和长生白云母产生了大约年龄为U-Pb的锆石。 １１１０ Ｍａ，这是高级变质作用和裂谷封闭的年代。这表明超大陆哥伦比亚的分解是在短时间内跟随着约270厘米的超大陆罗丹尼亚的组装。 1.1-1.0 Ga，并且说西亚马逊河带是在阿雷基帕-安托法拉地下室积聚到亚马逊克拉通期间形成的。

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