Assessment of Radioelements Host Potential Using Geophysical Methods in Gaya and Its Environs, Northwestern, Nigeria

Abstract

Radioactive mineral occurrences in Gaya and its environs, Northwestern Nigeria, have not been extensively studied using integrated airborne geophysical methods. This study aimed to delineate the Structural controls and assess the distribution of radioelements in the area to support mineral exploration and environmental safety evaluation. High-resolution aeromagnetic and aeroradiometric datasets (Sheet No. 82) from the Nigerian Geological Survey Agency were processed using Oasis Montaj and ArcGIS software. Data enhancement techniques included reduction to pole, analytical signal, first vertical derivative, source parameter imaging, ternary radiometric mapping, and dose rate estimation. Residual magnetic anomalies ranged from ?293.2 to 436.1 nT, with depth estimates indicating shallow sources (0.08–0.20 km) and deeper sources (0.26–0.80 km). Mean concentrations of potassium, equivalent uranium, and equivalent thorium were 0.70 %, 2.79 ppm, and 12.13 ppm respectively, with high-value zones aligning with NE–SW and NW–SE structural trends. Absorbed dose rates ranged from 0.97 to 464.33 nGy h?¹, averaging 47.09 nGy h?¹, which is well below IAEA and UNSCEAR safety thresholds. The findings confirm that mineralization is structurally controlled and provide a geophysical framework for targeted exploration, environmental monitoring, and sustainable resource development in the region.

Introduction

Nigeria is rich in solid minerals, including radioactive minerals like uranium and thorium, which have significant industrial and energy applications. Uranium is a nuclear fuel, while thorium is being explored as a safer, more abundant alternative. Both elements are found in measurable amounts in Nigerian rocks, and airborne geophysical surveys—especially magnetic and radiometric methods—are essential tools for their exploration.

Study Focus:

This study investigates the geophysical potential of radioelement-hosting minerals in Gaya and surrounding areas (Kano and Jigawa States, NW Nigeria). It integrates aeromagnetic and aeroradiometric data to map geological structures, identify mineralized zones, and interpret radioactive element distributions for improved mineral exploration.

Geological Setting:

The area comprises Younger Granites (Jurassic) and Pan-African Older Granites, with volcanic flows and dykes also present. These geological formations are favorable for radioactive mineral deposits.

Methodology:

Data Acquisition:

• Source: NGSA/Fugro Airborne Survey (2005–2009)

• Tools:

  • Scintrex CS-3 magnetometer

  • 256-channel gamma-ray spectrometer

• Survey Parameters:

  • Flight lines: NW–SE at 0.5 km spacing

  • Tie lines: NE–SW at 2 km spacing

  • Flight height: 80 m

Aeromagnetic Analysis:

• Reduction to Pole (RTP): Normalizes magnetic data

• First Vertical Derivative (FVD): Sharpens magnetic anomalies

• Analytic Signal & SPI (Source Parameter Imaging): Locate and estimate depths of causative bodies

• CET Grid Analysis: Identifies faults and structural complexities

Radiometric Analysis:

• Radioelement Mapping: Measures surface K, eTh, and eU concentrations

• Dose and Exposure Rate Calculation (IAEA formulas)

• K/eTh Ratio Map: Highlights hydrothermal alteration zones

• RGB Ternary Map (K–eTh–eU): Supports lithological and alteration zone identification

Results:

• Multiple anomaly points were identified across the study area using residual magnetic anomalies, SPI depth estimations, and ternary radiometric maps.

• Zones of high uranium, thorium, and potassium concentrations were found in localities such as Kanwa, Karnaya, Gaya, Garun Abaya, Wurnoma, Baranda, and Kude.

• Depths ranged from 0.08–0.7 km, indicating shallow and deep sources of radioactivity.

• Mesozoic Younger Granites (Myp) and Pan-African Older Granites (OGp) were the key host rock types.

• Directional trends of anomalies suggest mineralization zones align along NE, NW, SW, and SE orientations.

Conclusion

This study has demonstrated the effectiveness of integrating aeromagnetic and radiometric methods in delineating mineralization zones within the study area. The identified NE–SW and NW–SE structural trends, shallow magnetic source depths (0.08–0.20 km), and elevated uranium (up to 8.26 ppm), thorium (up to 35.47 ppm), and potassium (up to 3.96%) concentrations point to significant exploration potential. Key target zones, including Kanwa, Gurduba, and Wurnoma, display geophysical and geochemical characteristics consistent with mineralized systems. The measured average radiological dose rate (47.09 nGy h?¹) remains well below international safety limits, suggesting minimal environmental health risks. The correlation of current findings with previous regional surveys provides additional confidence in the interpretive results and confirms the structural and lithological controls on mineralization. Overall, the study offers a robust geophysical framework for guiding targeted mineral exploration while ensuring adherence to radiological safety standards.

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Copyright

Copyright © 2025 Babagana A. Mustapha, Mohammad Saleh, Umar Suleiman, Abba Kaka A. Modu, Maikori Bitrus Buba, Yakubu Ayuba Alak, Saidu Fika Ibrahim, Dashe Sylvia Tapsak. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.