Central Longitudinal Traverse Data-field Analysis of a 4 km2 VES study at the Southern Phase II Development, Gidan Kwano Campus, Minna, Nigeria

Abstract

Abstract When carrying out the data-acquisition phase of the 4 km2 areal extent VES survey at the southern Phase II Development, Gidan Kwano Campus, Minna, Nigeria, concomitant VES-IP surveys were ignored for the points of Profile 11 because the results of the dual VES-IP surveys for these points already existed in the longitudinal traverse (LT) format beyond the northernmost 21st 2 km linear extent station of the 4 km2 areal extent grid. The aim of this study is to process and interpret the central longitudinal traverse data-field of the 4 km2 VES study at the southern Phase II Development of the Gidan Kwano Campus in order to gain insight into the hydro-centric nature of the material along this mid-profile. The VES survey for the mid-profile of interest in this study was carried out over the spread of P11-1 to P11-34 in no particular order but a survey point being determined by the convenience and logistics of getting to that point on the day of survey. Essentially, the log-log plots show more three-layer geological formations along the line of study but there are points where a four-layer formation can also be discerned.; this three-layer structure is the expected norm at the local basement province of which this line of study is a part. The geologic cross-section shows the conventional and dominant three-layer representation of “top soil,” “weathered basement/laterite,” and “partly-fractured (fresh) basement.” The pseudosection plot shows that, at the lower slope of the line of survey, low-resistivity materials of the sub-300 Ωm range dominate at comparatively shallower depths; as the survey-station designation increases in numerals as one proceeds upslope of the line of survey, dominant higher-resistivity material of a uniform kind are noticed at depth-points deeper than the 20 m mark and this is prominent between P11-20 and P11-30; still higher resistive materials are noticed at the 40 m depth-mark downwards between P11-15 and P11-32 as they are noticed at the 30 m depth-mark downwards at P11-8 and P11-9. Overall, there is concentration of more prospect locations at the lower slope of the line of survey (P11-1, P11-2, P11-3, P11-4, P11-5, and P11-7) and at the northern end of the line of survey (P11-30, P11-31, P11-32, and P11-34). It is recommended that the groundwater prospect locations at P11-1, P11-2, P11-3, P11-5, P11-7, and P11-12 be integrated into the database of the existing 57 definite groundwater prospect locations inferred from the 4 km2 areal extent VES survey. As was done for the 4 km2 areal extent VES survey, the VES points that are flagged as prospects for this study should be subjected to an even more stricter control on their hydro-centric nature by making recourse to the concomitantly-acquired induced polarisation (IP) data at coincident points of surveys as those for the VES.