Scientific Reports (Nov 2024)
Exploring geothermal energy prospects through radioelement enrichment zones in Gabal Abu Hashim area in southeastern Aswan by geophysical and remote sensing data integration
Abstract
Abstract Alteration zones in the Eastern Desert are promising for minerals and geological resources exploration. Remote sensing and geophysical techniques offer cost-effective tools for identifying new exploration sites. Additionally, their use in mapping potential alteration zones is crucial for enhancing exploration. Geophysical and remote sensing data are integrated to perform a comprehensive study of minerals alteration associated with radioactive materials under controlling geological structures. This study aims to explore the associated radiogenic heat and geothermal energy to expand the geothermal resources assessments. The study utilizes Spectral Angle Mapper classification, band algebra, principal component analysis (PCA), surface lineament density, and decorrelation stretch techniques and Multiple Criteria Decision Analysis to enhance the mapping of mineralized alterations in the study area. It uses VNIR-SWIR ASTER data to identify hydrothermal alteration minerals and dominant alteration zones, also Landsat 8 Thermal Infrared Sensor (TIRS) offers two adjacent thermal bands, benefiting land surface temperature (LST) radiation from space in the Gabal Abu Hashim area. The area contains minerals alteration indicators like chlorite, alunite, illite, kaolinite, sericite, with less abundant ferrous minerals and epidote. Airborne gamma-ray spectrometry (AGRS) was used to identify naturally occurring radioactive anomalous zones, including potassium (K), equivalent uranium (eU), and equivalent thorium (eTh), to estimate the radiogenic heat production (RHP) in selected areas of the study area. The examination of AGRS data indicated that the studied region has radioelement concentrations ranging from 2.8 to 148 ppm, 18 to 144 ppm, and 0.004 to 9% of (eU), (eTh), and (K), respectively, indicating the existence of various rock types. The Radioelements Composite Image (RCI) successfully highlighted the radioelements enriched zones associated with younger granite, older granite, and metamorphic rocks, particularly those with extensive hydrothermal alteration. The results successfully discriminated alteration zones associated with radioelements K, U, and Th potential parts in the regional shear oblique zone. The weighted overlay GIS model was used to produce the alteration zones potentiality map, and to identify five zones of significant variations in heat production across different geological formations. The northern and southeastern regions demonstrate high alterations and land surface temperature corresponding to areas of high fault density and shear zones. The results of this study reveal that the proposed methods of remote sensing and AGRS data are effective in detecting areas rich in K, eU, and eTh in alteration zones associated with high radiogenic heat production in younger granite, older granite, and metamorphic rocks.
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