Abstract:
Integration of 2D geophysical methods, Electrical Resistivity Imaging (ERI) and Induced Polarization (IP) were used to study the subsurface geology and structures around Ihe pond, Nsukka in Anambra basin. The research work has delineated the geologic structures and strata responsible for the water in the pond, and determined the origin of the Pond. Three 2D resisitivity profiles of maximum spread lengths of 500, 400 and 500m were run around the pond. Horizontal profiling, using Wenner array configuration was employed in the data acquisition for both methods. Four faults designated Apo 1, 2, 3 and 4 with colour codes, blue, red, green and black and their fault zones were mapped. The faults were located at points 224, 265 and 325m on ER model line one, and at points 170, 205, 275 and 296m on ER model line two. Three lithologic units of consolidated coarse, medium grained, fine-grained sandstones and saturated zones were identified on the ER and IP Psuedosections. The ER and IP values from the three profiles range from 136 - 21559Wm and -81.0 to 240Ms respectively. The faults zone acts as water pathway to the pond. Inverse chargeability models established the faults zones, as large gradients of chargeability. Correlation of strata to known formation depicts the presence of consolidated coarse to medium grained sandstones, while known exposed fault was correlated to Apo 3 fault using coordinates readings. Analysed sample of water from the pond shows low Salinity and sulfides. Soil sample oxide content was also analysed to compliment the geology, and the result shows that Aluminum oxide (Al203), Silicon oxide (Si02), Ferrous oxide (Fe203), Zinc oxide (Zn0) and Sodium oxide (Na203) are relatively low and are in conformity with characteristics of laterite.
