The Tuareg shield was assembled by oceanic closures and horizontal movements along mega-shear zones between approximately 20 terranes during the Pan-African Orogeny (750–550 Ma). Although there is an ongoing debate about its origin, the exhumation of the Tuareg Shield is assumed to be related to Cenozoic intraplate volcanism. The Gour Oumelalen is a key region of the Tuareg shield and is located in the northeastern part of the Egéré-Aleksod terrane, corresponding to the eastern boundary of the Archean-Paleoproterozoic micro-continent LATEA (Central Hoggar). The eastern boundary of the study area corresponds to a Neoproterozoic suture zone separating two old micro-continents, LATEA and the Orosirian Stripe. We deployed two magnetotelluric (MT) profiles consisting of 33 broadband MT stations and combined these with aeromagnetic data, aiming to define the crustal structure in detail. The resistivity cross-sections obtained from the 3-D inversion of full impedance tensor and tipper data from stations along the profiles, confirm the main Precambrian faults, some of which are covered by Quaternary sediments and hence, have not yet been deciphered. The cross-sections also highlight the Cretaceous-Quaternary sedimentary basins represented by low resistivities. The upper crust is typically cratonic with a high electrical resistivity. On the contrary, the lower crust shows a drastic drop in resistivity (<10 Ωm). The most plausible hypothesis is that the study area corresponds to a Cretaceous rifting zone. The Cretaceous magmatic event and its related fluids and mineralization as well as the recent fluids associated with Cenozoic volcanism, are plausible causes of a very conductive lower crust. However, we cannot exclude other reasons such as: i) a high-temperature and strongly sheared mobile belt, or ii) a contribution of inheritance involving Pan-African events that affected this former suture area.

中文翻译：

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阿尔及利亚中部霍加尔市Gour Oumelalen地区前寒武纪地壳和板内新生代火山的大地电磁研究

在泛非造山运动（750-550 Ma）期间，图阿雷格盾构是由大洋封闭和沿大型剪切带的水平运动组装而成的，该剪切带位于大约20个地层之间。尽管有关其起源的争论一直在进行，但图阿雷格盾牌的发掘被认为与新生代板内火山活动有关。Gour Oumelalen是图阿雷格盾构的关键区域，位于Egéré-Aleksod地貌的东北部，与太古宙古古生代微大陆LATEA（霍加尔中部）的东部边界相对应。研究区域的东部边界对应于新元古代缝线区，该缝线区将两个旧的微大陆LATEA和Orosirian条带分隔开。我们部署了两个由33个宽带MT站组成的大地电磁（MT）配置文件，并将其与航磁数据相结合，目的是详细定义地壳结构。从沿剖面测站的全阻抗张量和倾卸器数据的3-D反演获得的电阻率横截面，证实了主要的前寒武纪断层，其中一些被第四纪沉积物覆盖，因此尚未被解密。横截面还突出了以低电阻率为代表的白垩纪-第四纪沉积盆地。上地壳通常是克拉通高电阻率的。相反，下地壳的电阻率急剧下降（<10Ωm）。最合理的假设是研究区域对应于白垩纪裂谷带。白垩纪岩浆事件及其相关的流体和矿化，以及与新生代火山活动有关的最新流体，可能是造成下层外壳导电性很强的原因。但是，我们不能排除其他原因，例如：i）高温强烈剪切的移动带，或ii）涉及泛非事件的遗传贡献影响了该前缝合区域。