Universal Journal of Geoscience Vol. 3(4), pp. 135 - 145
DOI: 10.13189/ujg.2015.030403
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Integrated Geophysical Mapping of Near-surface Structures and Utilities in Ile-Ife, Nigeria

Akindulureni John Olaolu ^*, Adepelumi Adekunle Abraham , Ebiko Olatunde
Department of Geology, Obafemi Awolowo University, Nigeria

ABSTRACT

Magnetic, self-potential (SP) and Ground-penetrating radar (GPR) methods were employed to investigate the near-surface conditions beneath a road in Obafemi Awolowo University Campus, Ile-Ife with the aim of mapping previously suspected dyke, fractures, buried utilities in the area. Fifty stations were established for the magnetic and SP methods along five and four traverses respectively while GPR data was acquired along three traverses, all parallel to the general strike of the rocks in the area (NW-SE). The magnetic and SP readings obtained were interpreted qualitatively and quantitatively using least-squares to identify the location/trends and determine source parameters of features of interest. Also, GPR sections were analyzed using basic radar processing tools. The magnetic field readings ranged from -310nT to 220nT while the SP readings with range -126mV to 55mV. The anomaly source was delineated on low closures on the iso-magnetic map while the inflexion points on the SP profiles lie above the target source. Results of quantitative interpretation of magnetic and SP anomalies revealed a spherical, sub-vertical source with depth to top values of 1.6m to 3.85m. The radargrams revealed the positions and depths of utilities such as pipes and cables, shallow-dipping fractures, a road culvert and partially weathered bedrock layers overlying fresh basement in the area. The penetration depth of the GPR was 14 m and the depth to top of the basement ranged from 4 m to 6 m. The techniques employed mapped the subsurface structural/cultural features in the study area and determined their positions and depth extents.

KEYWORDS
Self-potential (SP), Ground-penetrating Radar (GPR), Dyke, Fractures, Utilities

Cite This Paper in IEEE or APA Citation Styles
(a). IEEE Format:
[1] Akindulureni John Olaolu , Adepelumi Adekunle Abraham , Ebiko Olatunde , "Integrated Geophysical Mapping of Near-surface Structures and Utilities in Ile-Ife, Nigeria," Universal Journal of Geoscience, Vol. 3, No. 4, pp. 135 - 145, 2015. DOI: 10.13189/ujg.2015.030403.

(b). APA Format:
Akindulureni John Olaolu , Adepelumi Adekunle Abraham , Ebiko Olatunde (2015). Integrated Geophysical Mapping of Near-surface Structures and Utilities in Ile-Ife, Nigeria. Universal Journal of Geoscience, 3(4), 135 - 145. DOI: 10.13189/ujg.2015.030403.