<abstract xmlns="http://www.w3.org/1999/xhtml"><p>The study of the nature of distribution of natural radioelements in Ilesha and its environs with its geological structure has been studied using aeroradiometric data. Aeromagnetic data have also been subjected to three automated gradient techniques to delineate the sub-surface structure of the study area. From the study, it can be found that maximum values of “eU” (ppm) and “eTh” (ppm) fall within the branded gneiss, whereas the maximum value of K (%) falls within porphyritic granite regions. eTh had the highest radioactive content. The environmental dose rate of Ilesha was between 0.1817 and 3.9296 msv/yr. Although there were extreme values, but the mean dose rate was 0.522 ± 0.310 msv/yr (within acceptable safe limit of 1.0 msv/yr). eU/K, eU/eTh and eTh/K ratios were analysed for enrichment or depletion of radioisotopes. eU/eTh >1 showed uranium depletion, while eTh >2 showed eTh enrichment. The magnetic intensity values ranged from -79.41 to 140.93 nT. The horizontal gradient method (HGM) and analytic signal amplitude (ASA) revealed that depth to magnetic sources ranged from 0.478 to 4.112 km and 0.348 to 2.551 km, respectively, whereas local wavenumber (LWN) depth ranged from 0.478 to 5.48 km, which overestimated those compared using HGM and ASA functions. The apparent susceptibility ranged from -0.00325 to 0.00323 SI, showing that ferromagnetic and diamagnetic mineral ranges control apparent susceptibility in Ilesha.</p></abstract>

The study of the nature of distribution of natural radioelements in Ilesha and its environs with its geological structure has been studied using aeroradiometric data. Aeromagnetic data have also been subjected to three automated gradient techniques to delineate the sub-surface structure of the study area. From the study, it can be found that maximum values of “eU” (ppm) and “eTh” (ppm) fall within the branded gneiss, whereas the maximum value of K (%) falls within porphyritic granite regions. eTh had the highest radioactive content. The environmental dose rate of Ilesha was between 0.1817 and 3.9296 msv/yr. Although there were extreme values, but the mean dose rate was 0.522 ± 0.310 msv/yr (within acceptable safe limit of 1.0 msv/yr). eU/K, eU/eTh and eTh/K ratios were analysed for enrichment or depletion of radioisotopes. eU/eTh >1 showed uranium depletion, while eTh >2 showed eTh enrichment. The magnetic intensity values ranged from -79.41 to 140.93 nT. The horizontal gradient method (HGM) and analytic signal amplitude (ASA) revealed that depth to magnetic sources ranged from 0.478 to 4.112 km and 0.348 to 2.551 km, respectively, whereas local wavenumber (LWN) depth ranged from 0.478 to 5.48 km, which overestimated those compared using HGM and ASA functions. The apparent susceptibility ranged from -0.00325 to 0.00323 SI, showing that ferromagnetic and diamagnetic mineral ranges control apparent susceptibility in Ilesha.

High resolution airborne radiometric and magnetic studies of ilesha and its environs, southwestern Nigeria

Materials and Geoenvironment

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

The study of the nature of distribution of natural radioelements in Ilesha and its environs with its geological structure has been studied using...

High resolution airborne radiometric and magnetic studies of ilesha and its environs, southwestern Nigeria

Published Online: Aug 30, 2019

Page range: 51 - 73

Received: May 27, 2017

Accepted: Apr 09, 2018

DOI: https://doi.org/10.2478/rmzmag-2018-0020

Keywords
Aeromagnetic data, Apparent Susceptibility, Background Radiation Doses, Ilesha, Radiometric Data

© 2018 Okeyode I. C. et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

High resolution airborne radiometric and magnetic studies of ilesha and its environs, southwestern Nigeria

Published Online: Aug 30, 2019

Page range: 51 - 73

Received: May 27, 2017

Accepted: Apr 09, 2018

DOI: https://doi.org/10.2478/rmzmag-2018-0020

KeywordsAeromagnetic data, Apparent Susceptibility, Background Radiation Doses, Ilesha, Radiometric Data

© 2018 Okeyode I. C. et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
Aeromagnetic data, Apparent Susceptibility, Background Radiation Doses, Ilesha, Radiometric Data