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An integrated structural and geophysical approach to defining the structures of part of the Nangodi greenstone belt, northeastern Ghana
Journal of African Earth Sciences ( IF 2.2 ) Pub Date : 2021-04-27 , DOI: 10.1016/j.jafrearsci.2021.104238
Elikplim Abla Dzikunoo , Raymond Webrah Kazapoe , Jennifer Edzordzinam Agbetsoamedo

The application of integrated geophysical (aeromagnetic and airborne radiometric) and geological data has become more relevant in the investigation of subsurface geology with its inherent structures; this approach provides greater detail of structures and formations which are hidden beneath thick weathered zones. This approach was used to provide an in-depth study of the poly-deformational, structural and lithological character of parts of the Paleoproterozoic Nangodi Greenstone Belt in northeastern Ghana. The integrated method was specially chosen because of the paucity and lack of obvious lateral continuity of outcrops in much of the area. Processing and interpretation of aeromagnetic data led to the identification of structures and deformational features i.e. shear zones with related folds and faults. Combined with field evidence, three deformational events (D1-D3) were resolved within the study area. D1 is marked by NW-SE crustal shortening which was responsible for the production of macroscopic folds that imparted the regional NE-SW foliation observed in the rocks. D2, is a brittle-ductile deformational event mainly responsible for the production of a NE striking shear zone and some associated dextral strike slip faulting which were seen in the Gonzurudoug and Nangodi hills. D2 deformation is seen as an angularly hinged fold, described as an intramylonitic fold. D3 is responsible for the production of an ESE-WNW directed compressional force which produced folds with ENE striking axial planes as well as left lateral strike slip faults. Lithological boundaries were identified using ternary maps of radiometric data with confirmation from field observations.



中文翻译:

定义加纳东北部南迪迪绿岩带部分结构的综合结构和地球物理方法

综合地球物理(航空和航空辐射测量)和地质数据的应用在地下地质及其固有结构研究中变得越来越重要。这种方法提供了隐藏在厚厚的风化带之下的结构和地层的更多细节。这种方法被用来对加纳东北部的古元古代Nangodi绿岩带的某些部分的多变形,构造和岩性特征进行深入研究。之所以选择这种综合方法,是因为在该地区的大部分地区露头很少且缺乏明显的横向连续性。处理和解释航磁数据导致对结构和变形特征的识别,即具有相关褶皱和断层的剪切带。结合现场证据,在研究区域内解决了三个变形事件(D 1 -D 3)。D 1以NW-SE地壳缩短为标志,这是造成宏观褶皱的原因,这些褶皱赋予了在岩石中观察到的局部NE-SW叶面。D 2是脆性-延性变形事件,主要负责产生NE冲击剪切带和一些相关的右旋走滑断层,这在Gonzurudoug和Nangodi丘陵中可见。第2天变形被看做是一个有角度的铰接褶皱,被描述为一个亚分子内褶皱。D 3负责产生ESE-WNW定向的压缩力,该压缩力产生带有ENE撞击轴向平面的褶皱以及左侧横向走滑断层。使用放射数据的三元图确定岩性边界,并得到野外观测的证实。

更新日期:2021-05-08
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