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Geoelectrical characterisation of aquifers in Bauchi-Alkaleri-Kirfi geological transition zones, Northeast Nigeria
Environmental Earth Sciences ( IF 2.8 ) Pub Date : 2020-05-12 , DOI: 10.1007/s12665-020-08978-5
Abdullateef Lawal , Moshood N. Tijani , Matteo D’Alessio

Geological transition zones (GTZ) have proved to be hydrogeologically problematic, owing to poorly defined basal and lateral contacts between the rocks. Several occurrences of abortive wells in GTZ overtime has necessitated the need to characterise groundwater potential zones (GPZ) in these zones. Attempts have been made to delineate the complex lithological contacts in GTZ using geophysical and geological methods. However, the characterisation of groundwater prospective zones in these complex lithological contacts, which are very significant to the sustainable management of groundwater in GTZ, have not received much attention. Therefore, this study focused on the characterisation of the groundwater prospects of aquifers in a typical GTZ in Bauchi-Alkaleri-Kirfi areas, Northeastern Nigeria. Geological mapping was employed for the lithological delineation of rocks while geoelectrical mapping using 94 vertical electrical sounding (VES) was adopted for characterisation of subsurface media (aquifers). Three thematic maps comprising of aquifer resistivity, thickness and lithology were integrated using overlay analysis in the GIS environment to generate a GPZ map. Geologically, the basement part of the GTZ is underlain by migmatite, gneiss, granite and charnockite while the sedimentary areas were underlain by the sandstone units of the Tertiary Kerri Kerri Formation. The VES data indicated a generally 3–5 geoelectric layer system within the sedimentary zones with aquifer thickness of 11–158 m in the sandstones. However, the Basement Complex areas revealed saprolite thicknesses of 2.4–83.8 m (migmatite/gneiss), 1.3–67.3 m (granite) and 1.2–44.6 m (charnockite), suggesting a better aquiferous medium in the migmatite/gneiss units. Consequently, integration of thematic maps revealed three GPZ namely: poor zones (charnockite and granite), moderate zones (migmatite/gneiss and granite), and good zones (dominantly sandstone). This study shows the efficacy of applying GIS to VES data in groundwater exploration for better management of groundwater resources.

中文翻译:

尼日利亚东北部Bauchi-Alkaleri-Kirfi地质过渡带含水层的地电特征

事实证明,由于岩石之间的基础和横向接触不明确,地质过渡带(GTZ)在水文地质上存在问题。在德国技术合作公司加班期间多次发生流产井,因此有必要对这些地区的地下水潜在地带(GPZ)进行特征分析。已经尝试使用地球物理和地质方法来描述GTZ中的复杂岩性接触。然而,这些对复杂的岩性接触中的地下水潜在地带的表征对德国技术合作公司的地下水的可持续管理非常重要,但并未引起人们的广泛关注。因此,本研究着重于尼日利亚东北部的包奇-阿尔卡莱里-基尔菲地区典型GTZ中含水层的地下水前景特征。地质制图用于岩石的岩性圈定,而地电测绘则使用94垂直电测深(VES)来表征地下介质(含水层)。在GIS环境中使用覆盖分析将包括含水层电阻率,厚度和岩性的三个专题图进行了整合,以生成GPZ图。从地质学上来说,GTZ的基底部分是由蒙脱石,片麻岩,花岗岩和霞洛克岩所覆盖,而沉积区则由第三系Kerri Kerri组的砂岩单元所覆盖。VES数据表明,在沉积区内,砂岩的含水层厚度为11–158 m,通常为3–5地电层系统。但是,地下复杂区域的腐泥土厚度为2.4-83.8 m(蒙脱石/片麻岩),1.3-67.3 m(花岗岩)和1。2–44.6 m(方钠石),表明在辉石/片麻岩单元中较好的含水介质。因此,专题图的整合揭示了三个GPZ:贫困地带(菱镁矿和花岗岩),中等地带(蒙脱石/片麻岩和花岗岩)和良好地带(主要是砂岩)。这项研究表明,在地下水勘探中将GIS应用于VES数据可以更好地管理地下水资源。
更新日期:2020-05-12
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