Contribution of Magnetotelluric inversion and potential field modeling to map the Gour Oumelalen deep geological Structure, Central Hoggar, Algeria

IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY
Abdelghafour Boukar , Mohammed Djeddi , Mohamed Hamoudi , Abderrezak Bouzid
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Abstract

The Gour Oumelalen area is situated in the northern part of the Egere-Aleksod terrane (Central Hoggar, South of Algeria). This area is one of the best preserved Palaeoproterozoic and Archaean zones in Central Hoggar. The aim of this study based on a survey of 33 Magnetotelluric (MT) soundings, aeromagnetics and gravity data, is to investigate the crustal structure and its architecture beneath this area.

As the first stage, we have determined dimensionality of the regional electric conductivity structure. For this purpose, we have used the impedance and phase tensor approaches. Our results suggest that the underling regional conductivity structure is complex. In the central part it presents a 3D geometry, and beyond, it is mainly 2D; with a strike direction oriented in the North-South direction. Thus, the MT data were inverted using the Occam's inversion algorithm (v.3); which is a powerful tool to modeling and inverting the 2-D MT data. The obtained geo-eletric models, show clearly a high resistive upper crust with a resistivity up to 1000 Ω m; overlies a conductive lower crust with a resistivity approximately less then 100 Ω m. Although, our resulting cross-sections confirm the major Precambrian faults, especially the Ounan shear zone, which is characterized by a high conductivity anomaly.

At the second stage, using the joint modeling of gravity and magnetic data, we have characterized the different geological units. Although, our modeling reveals that the thicknesse of the upper crust is deeping toward the East, from 16 to 25 km. The Moho depth reaches an average value of 40 Km. Moreover, in the centre of the survey area, the Moho depth decreases and becomes equal to 20 Km. This uplifting of the upper mantle may corresponds to the high magnetic anomaly of the Tisseliline pluton. It seems also related to the magmatic intrusion along the Ounan Shear Zone.

磁位反演和电位场建模对绘制阿尔及利亚霍加尔中部 Gour Oumelalen 深部地质结构图的贡献
古尔乌梅拉伦地区位于埃盖尔-阿勒科索德地层(中部霍加尔,阿尔及利亚南部)的北部。该地区是霍加尔中部古生代和太古宙保存最完好的地区之一。这项研究基于对 33 个磁层探测(MT)、航空磁学和重力数据的调查,旨在研究该地区地下的地壳结构及其构造。为此,我们采用了阻抗和相位张量方法。我们的结果表明,区域导电结构的底层是复杂的。在中部,它呈现出三维几何结构,而在外部,它主要是二维结构;其走向为南北方向。因此,使用奥卡姆反演算法(v.3)对 MT 数据进行了反演;该算法是对二维 MT 数据进行建模和反演的强大工具。所获得的地质电学模型清楚地显示了电阻率高达 1000 Ω m 的高电阻率上地壳,覆盖着电阻率约小于 100 Ω m 的导电下地壳。第二阶段,我们利用重力和磁力数据联合建模,确定了不同地质单元的特征。尽管如此,我们的建模显示,上地壳厚度向东加深,从 16 千米到 25 千米不等。莫霍深度的平均值为 40 千米。此外,在勘测区域的中心,莫霍深度减小,等于 20 千米。上地幔的隆起可能与 Tisseliline 长岩的高磁异常相对应。这似乎也与沿乌南剪切带的岩浆侵入有关。
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来源期刊
Journal of African Earth Sciences
Journal of African Earth Sciences 地学-地球科学综合
CiteScore
4.70
自引率
4.30%
发文量
240
审稿时长
12 months
期刊介绍: The Journal of African Earth Sciences sees itself as the prime geological journal for all aspects of the Earth Sciences about the African plate. Papers dealing with peripheral areas are welcome if they demonstrate a tight link with Africa. The Journal publishes high quality, peer-reviewed scientific papers. It is devoted primarily to research papers but short communications relating to new developments of broad interest, reviews and book reviews will also be considered. Papers must have international appeal and should present work of more regional than local significance and dealing with well identified and justified scientific questions. Specialised technical papers, analytical or exploration reports must be avoided. Papers on applied geology should preferably be linked to such core disciplines and must be addressed to a more general geoscientific audience.
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