Abstract The Neoproterozoic Aracuai belt of eastern Brazil formed during the amalgamation of Western Gondwana and holds characteristics of a hot collisional belt, involving large amounts of magma, partial melting of the middle crust, and slow cooling rates. To improve our understanding of the mechanical behavior of the continental crust under these conditions we combined structural, magnetic, and geochronological studies to access information related to the flow of rocks, deformation history, and structural patterns associated with the behavior of this orogen. Anisotropy of magnetic susceptibility (AMS) coupled with rock magnetism investigations supports that the magnetic fabric is a good proxy of the structural fabric. Field and AMS measurements of syn-to late plutonic bodies hosted in metasedimentary rocks revealed four domains with contrasting fabric patterns. The structural patterns from W to E are characterized by westward thrusting orthogonal to the belt (region 1), orogen-parallel transpression induced strain partitioning (regions 2 and 3), and orogen-parallel flow and subsidiary eastward vergence magmatic flow (region 4). The use of AMS to determine the lineation was vital to unraveling the kinematics. The composite observed fabric results from the interplay of collision-driven and gravity-driven deformations, induced by the convergence between the Sao Francisco and Congo Cratons.

中文翻译：

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新元古代 Araçuaí 热造山带（巴西东南部）的中地壳变形机制变化：来自结构和磁性结构分析的见解

摘要 巴西东部新元古代阿拉库伊带形成于冈瓦纳西部并存过程中，具有热碰撞带的特征，岩浆量大，中地壳部分熔融，冷却速度慢。为了提高我们对这些条件下大陆地壳力学行为的理解，我们结合了结构、磁力和地质年代学研究，以获取与岩石流动、变形历史和与该造山带行为相关的结构模式相关的信息。磁化率各向异性 (AMS) 与岩石磁性研究相结合，支持磁性织物是结构织物的良好代表。沉积岩中的同-晚期深成体的场和 AMS 测量揭示了四个具有对比结构模式的域。W至E的构造模式以与带正交的西冲冲断带（区域1）、造山带平行挤压诱导应变分区（区域2和3）、造山带平行流和辅助东向辐合岩浆流（区域4）为特征. 使用 AMS 确定划线对于揭示运动学至关重要。观察到的复合结构是由圣弗朗西斯科克拉通和刚果克拉通之间的会聚引起的碰撞驱动和重力驱动变形相互作用的结果。造山带平行挤压诱导应变分割（区域 2 和 3），以及造山带平行流和辅助东向辐合岩浆流（区域 4）。使用 AMS 确定划线对于揭示运动学至关重要。观察到的复合结构是由圣弗朗西斯科克拉通和刚果克拉通之间的会聚引起的碰撞驱动和重力驱动变形相互作用的结果。造山带平行挤压诱导应变分割（区域 2 和 3），以及造山带平行流和辅助东向辐合岩浆流（区域 4）。使用 AMS 确定划线对于揭示运动学至关重要。观察到的复合结构是由圣弗朗西斯科克拉通和刚果克拉通之间的会聚引起的碰撞驱动和重力驱动变形相互作用的结果。