Geophysical investigation of remotely sensed suspected fault Zones around iwaraja-ijebu ijesa area of osun state, nigeria.
| dc.contributor.author | OKUNUBI, OLAJIDE MICHAEL | |
| dc.date.accessioned | 2023-05-13T17:57:18Z | |
| dc.date.available | 2023-05-13T17:57:18Z | |
| dc.date.issued | 2015 | |
| dc.description | 136p | en_US |
| dc.description.abstract | Magnetic profiling and electrical resistivity 2-D Dipole Dipole imaging and 1-D Vertical Electrical Sounding (VES) were carried out over two suspected remotely sensed delineated mega faults in the area around Iwaraja – Ijebu Ijesa in Osun State, Nigeria. This was with a view to establishing the existence of the mega structures. Four geophysical traverses varying in length from 1 to 4.55 km, were established across the suspected fault zones. Total field magnetic measurements were made at 10 m interval along each of the traverses and the corresponding base stations. The measurements were corrected for diurnal variation and offset using standard methods. The residual magnetic profiles were qualitatively interpreted and semi-quantitatively inverted into 2-D subsurface images. Dipole- Dipole resistivity profiling was carried out along profiles with lengths varying from 520 – 600 m, constrained by the magnetic model. A dipole length of 20 m and inter dipole expansion factor (n) varying from 1 to 5 were adopted. The Dipole Dipole data were subsequently inverted into 2-D resistivity structures. The VES involving the Schlumberger array were carried out along the Dipole Dipole profiles. The VES sounding curves were quantitatively interpreted using the partial curve matching technique and computer assisted 1-D forward modeling. The interpretation results were used to generate geoelectric sections. The magnetic profile and model; 2-D resistivity structure and geoelectric section were synthesized along each investigated traverse and used to establish the existence of the suspected fault zones. Five VES type curves comprising HA, KH, AKH, HKH and HKHKH were obtained. Five geologic layers comprising the topsoil, laterite, weathered layer, weathered/fractured basement and fresh basement were delineated. Synthesized images along Traverse 1 (TR 1b) showed an undulating magnetic basement relief, overburden thicknesses varying from 3.0 to 50.0 m and signatures of steeply dipping suspected fault zone, centered around distance 460 m and about 100 m wide. The synthesized images along a segment of Traverse 2 (TR 2a) showed gently undulating basement relief; overburden thicknesses varying from 1 to 20 m and characteristic feature of a steeply dipping suspected fault zone with center at around 1335 m and width of about 60 – 200 m. Over another segment of Traverse 2 (TR 2b), the synthesized images delineated overburden thicknesses varying from 20 – 90 m and a suspected steeply dipping fault centered at 4460 m and about 200 m wide. Along a segment of Traverse 3 (TR 3), the magnetic model delineated overburden thicknesses varying from 25 – 30 m and a diagnostic signature of a typical fault zone centered at around distance 2160 and about 90 m wide. The correlated centers of the geophysically delineated fault zones A' and B' along Traverses TR 3 and 2b and TR 1b and 2a respectively were shifted northward away from the corresponding centers of the remote sensing delineated fault zones A and B. The study concluded that the remotely sensed delineated suspected mega structures A and B existed but were spatially shifted north of their present locations. | en_US |
| dc.identifier.uri | https://ir.oauife.edu.ng/123456789/5558 | |
| dc.language.iso | en | en_US |
| dc.subject | Iwaraja | en_US |
| dc.subject | Osun State | en_US |
| dc.subject | Nigeria | en_US |
| dc.subject | Magnetic | en_US |
| dc.subject | geophysical | en_US |
| dc.title | Geophysical investigation of remotely sensed suspected fault Zones around iwaraja-ijebu ijesa area of osun state, nigeria. | en_US |
| dc.type | Thesis | en_US |