Abstract The Neoproterozoic Brasiliano Orogeny shaped the former Sao Francisco paleocontinent into a preserved cratonic nucleus surrounded by a pericratonic region. In central Brazil, this pericraton crops out as the Goias Massif, the basement of the northern Brasilia Belt. The well-known difficulty of tracing suture zones on surface led to a longstanding dispute on whether the Rio Maranhao Thrust, a structure separating the Internal Zone and the External Zone of the Brasilia Belt, marked the Brasiliano suture. This interpretation was largely based on regional gravimetric data showing a steep discontinuity at depth, between these zones. However, the Rio Maranhao Thrust separates two pericratonic domains of the Goias Massif (Campinorte Domain and Cavalcante-Arraias Domain), which otherwise share similar Paleoproterozoic ages and geology. To properly address the main structural boundaries within the northern Brasilia Belt, this work was focused on comparing shallow and deep gravity and magnetic data processed as enhanced anomalies and through matched filter analysis. Our results show that the large mafic-ultramafic complexes within the Internal Zone of the Brasilia Belt are masking a smooth gravimetric transition into the External Zone. Additionally, the alleged suture zone is coincident with the Mesoproterozoic rift-related Juscelândia and Palmeiropolis volcano-sedimentary sequences, which have been largely ignored in their role as creating magnetic and gravity suture-like signatures. Along with previous structural and geochronological data, our results argue against the Rio Maranhao Thrust as a suture zone and, instead, support the alternative interpretation of the thrust as an intracontinental feature within a portion of the Sao Francisco pericraton. This pericratonic region, unliked the preserved cratonic core, was widely affected by Mesoproterozoic rifting and Neoproterozoic thick-skinned thrusting. The Rio Parana Thrust, on the other hand, is unnoticeable below 8 km depth in gravity and magnetic data, suggesting thin-skinned tectonics also associated with the Brasiliano Orogeny. Finally, the relative crustal homogeneity from the Sao Francisco craton into the Goias Massif evidenced by our gravity data and confirmed by first- and second-order magnetic lineaments confirms the nature of a pericraton with dominantly NE (N20-40E) trending lineaments. These lineaments were progressively overprinted by Brasiliano NNE (N45-70E) structures from the western margin of the External Zone into the Internal Zone.

中文翻译：

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从地壳磁源和重力源解释的西圣弗朗西斯科周缘克拉通

摘要 新元古代巴西利亚诺造山运动将前圣弗朗西斯科古大陆塑造成一个保存完好的克拉通核，周围环绕着一个克拉通地区。在巴西中部，这个 pericraton 作为巴西利亚带北部的地下室 Goias Massif 出现。众所周知，在地表追踪缝合带的困难导致了长期以来的争论，即分隔巴西利亚带内带和外带的结构——Rio Maranhao 逆冲断层是否标志着巴西利亚诺缝合带。这种解释主要基于区域重力数据，显示这些区域之间的深度存在陡峭的不连续性。然而，Rio Maranhao 逆冲断层将戈亚斯地块的两个周界域（Campinorte 域和 Cavalcante-Arraias 域）分开，否则它们具有相似的古元古代时代和地质。为了正确解决巴西利亚带北部的主要结构边界，这项工作的重点是比较浅层和深层重力和磁数据作为增强异常处理并通过匹配过滤器分析。我们的结果表明，巴西利亚带内部区域内的大型镁铁质-超镁铁质复合体掩盖了向外部区域的平稳重力过渡。此外，所谓的缝合带与中元古代裂谷相关的 Juscelândia 和 Palmeiropolis 火山沉积序列重合，它们在产生磁性和重力缝合线样特征时在很大程度上被忽略了。连同先前的结构和地质年代学数据，我们的结果反对将 Rio Maranhao 逆冲断层作为缝合带，相反，支持将推力解释为圣弗朗西斯科周边部分大陆内特征的另一种解释。与保存下来的克拉通核心不同，这个周克拉通地区受到中元古代裂谷和新元古代厚皮逆冲的广泛影响。另一方面，Rio Parana 断层在 8 公里深度以下的重力和磁力数据是不明显的，这表明薄皮构造也与巴西利亚诺造山运动有关。最后，我们的重力数据证明了从圣弗朗西斯科克拉通到戈亚斯地块的相对地壳同质性，并由一阶和二阶磁线证实，证实了具有主导 NE (N20-40E) 趋势线的周克拉通的性质。