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首页> 外文期刊>Catena: An Interdisciplinary Journal of Soil Science Hydrology-Geomorphology Focusing on Geoecology and Landscape Evolution >The Cenozoic deposits of the ancient landscapes of Quadrilatero Ferrifero highlands, Southeastern Brazil: Sedimentation, pedogenesis and landscape evolution
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The Cenozoic deposits of the ancient landscapes of Quadrilatero Ferrifero highlands, Southeastern Brazil: Sedimentation, pedogenesis and landscape evolution

机译：Quadrilatero Ferrifero Highlands，巴西东南部的古老景观的新生代矿床：沉积，基础和景观演变

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摘要

The Quadrilatero Ferrifero (QF), Southeastern Brazil, is a very important tropical highland region in the world's geological context for its large and diverse Archean and Proterozoic rocks with great reserves of gold, iron, manganese, aluminum and industrial rocks, on a apparently stable geological structure. There, Cenozoic deposits perched on highland valleys show unclear genetic relationships with the underlying bedrock, with no apparent regional correlation. We studied five representative Cenozoic deposits (BR356, Agua Limpa, Padre Domingos, Pau Branco and Casa de Pedra) on the highlands of the Serra da Moeda syncline, Western QF, to answer the question of their sedimentological origin, and investigate their pedological evolution. Field sampling was complemented by macromorphological, mineralogical and micromorphological analysis supported by X-ray diffraction (XRD), differential thermal analysis (DTA), infrared analysis (IR), scanning electron microscopy (SEM), micropobre and transmission electron microscopy (TEM). The evolution of these isolated highland deposits comprises a deep-weathered source area, a tectonic activity, besides sedimentological and pedological processes, during and after the deposition. The deposits overlie deep saprolites of Precambrian rocks (Piracicaba and Itabira Groups), representing unconformable contact. The onset of the deposition was marked by torrential, coarse colluvial and large blocks landslides into the small basins generated by reactivating tectonic events during the Oligocene, producing local grabens. These tectonic basins were filled by cohesive debris and mudflow from the adjacent and previously laterized cover, developed under the hot and humid climate in the Eocene. The cover reveals an upside-down lateritic profile where morphology and kaolinite crystal properties (values of size of coherent scattering thickness ranging from 135 angstrom to 162 angstrom) in the bottom is related to the pedolith horizons of the former lateritic cover. Later, due to climate changes (during and after the Miocene), renewed weathering on these pre-weathered sediments occurred, characterized by alternating ferruginization and Fe-losses, with the superimposed generation of new pedogenic features such as nodules, ferruginous duricrusts and mottling (redox features). In addition to demonstrating that the Brazilian platform was not stable during the Cenozoic, these deposits reveal the role of polygenetic tropical pedological processes in their formation and transformation.
机译：巴西东南部的Quadrilatero Ferriferero（QF）是世界上一个非常重要的热带高地地区，为其大型和多样化的阿军和平面岩石，具有良好的金，铁，锰，铝和工业岩石，显然稳定地质结构。在那里，新生代矿床栖息在高地山谷上，展示了与底层基岩的遗传关系，没有明显的区域相关性。我们研究了五个代表新生代存款（BR356，Agua Limpa，Padre Domingos，Pau Branco和Casa de Pedra）在Serra da Moeda Syncline，西QF的高地，回答了他们的沉积物来源的问题，并调查了他们的粪便进化。通过X射线衍射（XRD），差分热分析（DTA），红外分析（IR），扫描电子显微镜（SEM），微孔和透射电子显微镜（TEM），通过X射线衍射（XRD），差分热分析（DTA），红外分析（SEM），扫描电子显微镜（SEM）（TEM）辅以抗体采样。这些孤立的高地沉积物的演变包括深度风化的源区，构造活动，除沉积物和沉积过程中，在沉积期间和之后。沉积物覆盖了前皮岩（Piracicaba和Itabira组）的深藏耳，代表了不可形成的接触。沉积的发作标记为Torrive，粗血管和大块粘连到通过再激活寡茂期间的构造事件产生的小盆地，产生局部Grabrens。这些构造盆地通过粘性碎屑和来自邻近的和先前的后盖的泥浆填充，在虫中的热和潮湿的气候下开发。盖子揭示了倒置的后晶型材，其中形态和高岭石晶体特性（底部的135埃至162埃的相干散射厚度的值）与前后覆盖的鞋垫视野有关。后来，由于气候变化（在中世内期间和后期），在这些预测沉积物上更新风化，其特征在于交替的铁灭绝和Fe-损失，具有叠加的新的基础特征，如结节，铁艺杜兰氏菌和斑点（氧化还原特征）。除了表现出在新生代期间巴西平台不稳定之外，这些存款揭示了多基热带科学过程在其形成和转化中的作用。

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