Outcrop mapping as well as electromagnetic and ground magnetic surveys was carried out within Auchi and Igarra localities in order to attempt an interpretation of the geology of the areas and to delineate the boundary between basement and sedimentary terrains. Geologic mapping was done by collecting samples of outcrops at five different locations within the areas. Three lithofacies were identified within Auchi area and they are the basal shale unit, tabular cross-bedded sandstone unit and ferruginized sandstone unit. The pebbly shale is greyish black in colour; the cross-bedded sandstone unit is greyish white, coarse-grained at the base and finer at the top with pockets of clay, while the ferruginized sandstone is dark red. Rocks of the Precambrian basement complex underlie Igarra area. The area is underlain by metasediments that have been intruded by igneous rocks. Results show the presence of three major groups of igneous and metamorphic rocks within the area, and they are the migmatite–gneiss complex, metasediments and porphyritic granites. The electromagnetic and ground magnetic data acquired along Profile X located along Auchi–Igarra–Ibillo road were processed using Microsoft Excel Software and the resulting plots delineated areas with lower electrical conductivities and higher magnetic susceptibilities, as well as areas with higher electrical conductivities and lower magnetic susceptibilities. The areas with lower electrical conductivities and higher magnetic susceptibilities are interpreted to be underlain by basement rocks, while the areas with higher electrical conductivities and lower magnetic susceptibilities are underlain by sedimentary rocks. The plots also delineated the most likely basement–sedimentary boundary in the area.

在 Auchi 和 Igarra 地区进行了露头绘图以及电磁和地磁勘测，以尝试解释该地区的地质情况并划定基底和沉积地形之间的边界。地质填图是通过在区域内五个不同位置收集露头样本来完成的。Auchi地区共识别出3种岩相，分别为基底页岩单元、板状交错层状砂岩单元和铁锈砂岩单元。卵石页岩呈灰黑色；交错层状砂岩单元呈灰白色，底部为粗粒，顶部较细，带有少量粘土，而铁质砂岩为深红色。前寒武纪基底复合体的岩石位于伊加拉地区。该地区的下方是被火成岩侵入的变质沉积物。结果表明该地区存在三大类火成岩和变质岩，它们是混合岩-片麻岩杂岩、变沉积岩和斑状花岗岩。沿位于 Auchi-Igarra-Ibillo 公路的 Profile X 获取的电磁和地磁数据使用 Microsoft Excel 软件进行处理，生成的图描绘了具有较低电导率和较高磁化率的区域，以及具有较高电导率和较低磁化率的区域敏感性。具有较低电导率和较高磁化率的区域被解释为基底岩石的下方，而具有较高电导率和较低磁化率的区域则为沉积岩。这些地块还划定了该地区最可能的基底-沉积边界。