Gravity survey of parts of SouthWestern Nigeria
| dc.contributor.author | Adejuwon, Benjamin Bukola | |
| dc.date.accessioned | 2025-04-30T11:25:55Z | |
| dc.date.available | 2025-04-30T11:25:55Z | |
| dc.date.issued | 2021-12 | |
| dc.description | This thesis is for the award of Doctor of Philosophy (PhD.) in Geophysics | |
| dc.description.abstract | Ground gravity survey was carried out in the southwestern part of Nigeria within the areas underlain mainly by the Basement Complex rocks. The study area is precisely bounded by Latitudes 70 00’N – 8000’N and Longitudes 40 30’E – 6 00’E. The work is aimed at producing a comprehensive interpreted structural and geological models and maps from the gravity data as an aid to mineral investigation, structural and crustal studies. One thousand and ninety-three (1,093) gravity data points were established in an area of 18,150km2 giving a density of 1/16.6km2 . This is a positive improvement on the existing 1/9,075km2 gravity density in the area. Seventy-five (75) evenly distributed gravity base stations were established in the study area. These were tied to IGSN 71 through the PGNN Base station at Oshogbo and Akure base stations. This gives a gravity station density of 1/242km2 as against the existing density of 1/9,075km2 . The database was also saved in GIS platform for proper management and archiving. One hundred and forty-eight (148) rock samples were collected and their densities determined using a standard density determination procedure. The density values ranged from 2.526 to 2.871g/cm3 . The amphibolites have the highest mean density of 2.765g/cm3 , followed by the charnockites with 2.755g/cm3 . The processed data were presented as 2D maps with both contour and colour shaded maps. The maps include absolute gravity value map, Free-air anomaly map, Bouguer anomaly map, Regional anomaly map, residual anomaly map and rock density anomaly map of the area. The Bouguer anomaly field values range from about -19.087 to 16.914mGal, the free-air anomaly values range from 16.026 to 68.274mGal/m while the residual Bouguer Anomaly values range from about -10.577 to 19.805mGal. There is mostly a general NE/SW and few N/S trends in all the anomaly fields. Four gravity profiles across the study area were chosen for modelling and interpretation. Six major bouguer anomalies with unique characteristic features were identified. These maybe related to the contrasting lithological and structural features. These include the Ifewara-Ilesha-Ilaorogun High, AkureIkere-Igbaraoke High, Ikare-Ogbagi-Ajowa High, Ute-Uzebba High, IjeshaIsu-Ikole-Ponyan Low and Ondo-Bagbe Low. The elongated NE/SW trending bouguer anomaly at the western part of the study area termed the Ifewara-Ilesha-Ilaorogun High coincide with the geologically established shear zone associated with Ifewara-Zungeru fault system in orientation and location. Hence, the gravity data have confirmed the existence of the mega fault system which is related to gold mineralization within the Ilesha Schist belt. In the same vein, the relatively high oval shaped bouguer anomaly “Ikare–Ogbagi-Ajowa high” at the NE part of the study area can be a new frontier for mineral exploration. Such anomaly needs further exploration using other geophysical and geochemical techniques to determine its mineral potential. | |
| dc.identifier.citation | Adejuwon, B. B. (2021). Gravity survey of parts of SouthWestern Nigeria (Unpublished Doctoral Thesis). Federal University of Technology, Owerri, Nigeria | |
| dc.identifier.uri | https://repository.futo.edu.ng/handle/20.500.14562/1810 | |
| dc.language.iso | en | |
| dc.publisher | Federal University of Technology, Owerri | |
| dc.rights | Attribution-NonCommercial-ShareAlike 4.0 International | en |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-sa/4.0/ | |
| dc.subject | Gravity survey | |
| dc.subject | basement complex | |
| dc.subject | base stations | |
| dc.subject | bouguer anomaly | |
| dc.subject | rock density | |
| dc.subject | fault | |
| dc.subject | mineral | |
| dc.subject | orientation. | |
| dc.subject | Department of Geology | |
| dc.title | Gravity survey of parts of SouthWestern Nigeria | |
| dc.type | Doctoral Thesis |