Groundwater potential of some parts of Cross River State, Nigeria, was assessed involving vertical electrical sounding (VES) and high-resolution aeromagnetic methods (HRAM). The VES and HRAM dataset were used to delineate the hydro-lithostratigraphic units and map the spatial distributions of geologic structures, respectively. The electro-stratigraphic sections revealed the various hydro-lithostratigraphic units composed of fractured/weathered crystalline basement, sandstones, siltstones, sandy shales, and highly baked and fractured shales occurring at different depths. Generally, the unsaturated top layer is composed of shales, marl, clay, silt, gravel and lateritic materials with resistivity ranging from ~ 3.0 to ~ 550 Ω m. This layer is underlain by various aquifer units like sandstones, siltstones, fractured shales and limestone/marl, and fractured/weathered basement occurring at different depths (~ 30 to ≤ 100 m) as revealed by the electro-stratigraphic sections obtained in the study area. In the Calabar Flank (CF), Oban Massif (OM) and Ikom-Mamfe Embayment (IME), the apparent resistivity for these hydro-lithostratigraphic units varied between ~ 8.50 and ~ 59.50 Ω m, ~ 120.2 and ~ 1562.6 Ω m and ~ 30.8 and ~ 277.2 Ω m, respectively. The enhanced total magnetic intensity maps and source parameter imaging result showed that the OM and IME are characterized by high concentration of short-wavelength anomalies, while the CF is dominated by relatively undisturbed thick sedimentation (~ 6217 m). HRAM results show that such areas are predominated by geologic structures like faults, fractures, fissure, dyke swamps, etc. caused by tectonics. Such geologic structures create secondary porosity and enhance permeability. From all the results obtained, OM and IME represent areas with moderate groundwater potential. The CF dominated by argillites with no significant tectonic activity is observed to have low groundwater potential.

中文翻译：

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利用地球物理数据评估地下水潜力：以尼日利亚东南部克罗斯河州部分地区为例

对尼日利亚克罗斯河州某些地区的地下水潜力进行了评估，包括垂直电测深（VES）和高分辨率航空电磁法（HRAM）。VES和HRAM数据集分别用于描绘水文岩层单位和绘制地质构造的空间分布图。电地层剖面揭示了各种水文-地层单元，包括断裂/风化的晶体基底，砂岩，粉砂岩，砂质页岩，以及在不同深度发生的高度烘烤和断裂的页岩。通常，不饱和顶层由页岩，泥灰岩，粘土，粉砂，砾石和红土材料组成，其电阻率约为3.0到550Ωm。该层由各种含水层单元所覆盖，如砂岩，粉砂岩，裂缝性页岩和石灰岩/泥灰岩，研究区域的电地层剖面显示，裂缝和风化的地下室发生在不同的深度（约30至≤100 m）。在卡拉巴尔侧翼（CF），奥本断层块（OM）和Ikom-Mamfe Embayment（IME）中，这些水文地层单元的视在电阻率在〜8.50和〜59.50Ωm，〜120.2和〜1562.6Ωm和〜之间变化。 30.8和〜277.2Ωm。增强的总磁强度图和源参数成像结果表明，OM和IME的特征是短波异常高度集中，而CF则以相对不受干扰的厚沉积（〜6217 m）为主。HRAM结果表明，这类地区以构造构造引起的断层，裂缝，裂隙，堤坝沼泽等地质结构为主。这样的地质结构产生了次级孔隙度并增加了渗透率。从获得的所有结果中，OM和IME代表具有中等地下水潜力的区域。观察到以没有显着构造活动的泥石质为主的CF具有较低的地下水潜力。