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Geophysical evidence for doming during the pan-african/brasiliano orogeny in the seridó belt, borborema province, brazil
Precambrian Research ( IF 3.2 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.precamres.2020.105870
Nitzschia R.R. Domingos , Walter E. Medeiros , Roberto G. Oliveira

Abstract The Neoproterozoic Serido belt located in the Borborema Province, NE Brazil, was deformed and metamorphosed in the Pan-African/Brasiliano orogeny. The basement rocks of the belt were submitted to intense partial melting to form dome-like structures as documented in the Santa Luzia anatetic dome. The aeromagnetic map of the Serido belt shows a long-wavelength anomaly with elongated sigmoidal shape, whose limits coincide with shear zones. Comparison with gravity data shows that both anomalies share common sources, which are felsic rocks more magnetic and less dense than the surrounding crust. Correlation with geology shows that the geophysical anomalies are associated with magnetite-rich migmatites and granites. We modelled the geophysical datasets using magnetic susceptibility and density values from measurements in cores of a stratigraphic borehole. The results are consistent with a migmatite-dome system formed in the south-central part of the belt. This large-scale crustal structure is composed of elongated internal domes, which were geophysically modelled as four anomalous bodies, that resulted from partial melting of rocks mostly of the basement. The anomalies define an elongated migmatite-dome system with the main axis in the NNE-SSW direction that progressively bends to E-W approaching to the Patos shear zone, thus indicating that this shear zone had a key role in shaping the domic structure. The migmatitic domes of the Serido belt compose a fault-related dome system, formed in association with the broad strike-slip shear zone array of the Patos-Serido system, which evolved through the crustal extrusion resulting from the continental collisions that amalgamated West Gondwana in the Ediacaran.

中文翻译:

巴西博尔博雷马省塞里多带泛非/巴西造山运动期间隆起的地球物理证据

摘要 位于巴西东北部博博雷马省的新元古代塞里多带在泛非/巴西造山运动中发生变形和变质。带的基底岩石经历了强烈的部分熔化,形成了圆顶状结构,如 Santa Luzia anatetic 圆顶中所记录的那样。Serido 带的航磁图显示了一个长波异常,呈细长的 S 形,其界限与剪切带重合。与重力数据的比较表明,这两个异常具有共同的来源,即与周围地壳相比磁性更强、密度更低的长英质岩石。与地质的相关性表明地球物理异常与富含磁铁矿的混合岩和花岗岩有关。我们使用来自地层钻孔岩心测量值的磁化率和密度值对地球物理数据集进行建模。结果与形成于带中南部的混合岩穹窿系统一致。这种大规模的地壳结构由拉长的内部圆顶组成,这些圆顶在地球物理上被模拟为四个异常体,这是由于大部分基底的岩石部分熔化造成的。这些异常定义了一个细长的混合岩穹顶系统,其主轴在 NNE-SSW 方向逐渐弯曲到 EW 接近帕托斯剪切带,因此表明该剪切带在塑造穹顶结构中起着关键作用。Serido 带的混合穹窿构成了一个断层相关的穹窿系统,
更新日期:2020-11-01
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