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Titre : Gold Exploration at Um Balad Area, North Eastern Desert, Egypt, Using Remote Sensing Techniques and Geophysical Data

Auteur : Abd El-Rahman, Mahmoud Abd El-Rahman Ibrahim.

Etablissement de soutenance : Ain Shams University

Grade : Doctor of Philosophy (PhD) in Geophysics 2022

Résumé partiel
The future of Egypt’s economy and development is challenged by the exploration of its mineral resources. Many of these mineral deposits are still poorly mapped and defined, despite the fact that there are various geological metallogenic maps accessible. Using satellite imaging technology and modern earth observational techniques, it is possible to discover alteration zones holding rich mineral deposits as well as determine their precise location and extent. The extraction of alteration mineral zones and lithological discrimination as a strategy for gold exploration were showing tremendous promise when new approaches for ASTER multispectral data and gamma-ray spectrometric data are combined. An enhanced lithological map and the main lithological units have been identified using a combination of remote sensing methods, including FCC, CRC, PCA, and MNF. Additionally, methods like MTMF, SAM, and SID helped to define the alteration zones related to gold mineralization. The alteration zones generated by the presence of the specified alteration minerals using the three classification approaches had the same positions. Using the selected approaches for alteration mapping and the automatically derived lineaments, the majority likely locations for zones of mineral-bearing hydrothermal alteration were defined. The main alteration minerals that were extracted overlap with areas of high/moderate lineament density, demonstrating the spatial distribution of alteration zones and related minerals in the research area. As a result, regions with comparable circumstances were thought of as possible mining exploration zones. The lineament density map will be even more useful when combined with details about the area’s alteration zones, which have been effectively characterized using a variety of methodologies. Gamma-Ray Spectrometric data was utilised for mapping the alterations caused by hydrothermal activity. The eTh ppm, K %, and eU ppm maps were employed as enhancement techniques. It is showed that the magmatic intrusion and hydrothermal alteration processes that caused the alteration were significantly related to a decrease in thorium and uranium and a rise in potassium throughout regional tectonic activity. Potassium is frequently the significant valuable element for regions of gold mineralization because of the high concentration in the altered rock that surrounds the deposits. Wherever gold-related alterations were discovered in quartz veins, these veins are typically having low radioelements ; however the hydrothermally altered host rocks typically have a distinctive signature of radioelement that is helpful for investigation. Regarding the radioelement composite map, the high colour values are clearly identified from the low radioactive rocks by their significant geographic correlation with the abnormally high concentrations of K, eU, and eTh, and are often defined by their strong radiometric responses. The eU-(eTh/3.5) map illustrates how uranium was mobilized toward the mineralized zone as altered rocks were subjected to hydrothermal fluids which could lead to mineralization. Regarding the eTh/K ratio, when it is low, it is considered one of the ideal markers of potassium alteration. Because enriched uranium occurs related to the potassium anomaly, radioelement ratio maps, such as the eU/K and eU/eTh maps, highlight the effects of hydrothermal activity. Regions with anomalies with high F-parameter values are those where potassic alterations have had a significant impact. Thorium normalizing method in which locations with anomalous low Kd percent coupled to abnormal uranium variation Ud percent are recognized as prospective mineralization hotspots. As a result of the integration of remote sensing and

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