الفهرس 
Chapter (1): IntroductionOnly 14 pages are availabe for public view
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Abstract
The Arabian-Nubian Shield (ANS) is a complex tectonic unit which formed throughout the Neoproterozoic Era and is characterized by distinct suture zones marked by ophiolite assemblages. In Egypt, the ANS is well-preserved and hosts valuable mineral deposits. This study examines five specific areas in the southern Eastern Desert, namely Madari, Sol-Hamed-Malogrem, Wadi Misah-Gabal Oshkafa, Elba manganese deposits and Sol-Hamed magnesite deposits with the aim of understanding their geological features and mineralization potential.
Placer gold deposition in the Madari gold mine is a result of weathering of the nearby gold-bearing quartz veins. Shallow braided channels and alluvial fan sequences contain gold concentrations ranging between 0.2-2.3 ppm, with finer gold found in lag deposits. Complex gold mineralization in the Madari includes various trends of smoky and white quartz veins with altered wall rocks, that considered a source of placer gold deposits.
Madari area in the ANS exhibits dismembered ophiolites with gold-bearing quartz veins ranged from 0.1-0.3 m in thickness, and extend up to 600 m. The Au concentrations range from 0.00 to 3.08 ppm. Previous gold mining activities and the presence of ENE-WSW dextral strike-slip faults indicate that Madari gold mineralization is structurally controlled.
Ophiolitic serpentinites are considered the sources of gold mineralization in the Sol-Hamed area as vein type deposits and often found in island-arc volcanics. Sheared serpentinites exhibit extensive alterations, including talc- and quartz-carbonate rocks, and contain Au mineralization. Fractured malachite-bearing and sheared smoky quartz veins have high-grade gold associated with sulfide minerals. Alteration zones with hematite, limonite, goethite, and pyrite occur near gold-bearing quartz veins.
The Sol-Hamed region in the south Eastern Desert of Egypt is a portion of the ANS ophiolites located within the suture zone of Onib-Sol Hamed. It consists of serpentinite, metagabbro, and arc metavolcanics, intruded by gabbroic and granitic rocks. Enrichment of compatible trace elements suggests a depleted peridotite source with a forearc basin setting. Highly sheared smoky quartz veins with iron oxides contain high-grade gold (average Au= 0.01-5.9 ppm) associated with arsenopyrite mineralization.
The Wadi Misah-Gabal Oshkafa area is characterized by metavolcanic, metagabbro-diorite, and tonalite-granodiorite rocks. Gold mineralizations are confined to quartz vein systems within intermediate to acidic metavolcanics. The Oshkafa gold occurrence includes five gold-bearing quartz veins, while the area also exhibits three alteration zones). The gold concentrations range from 0.7 ppm to 16.6 ppm.
Metagabbroic rocks in Wadi Misah-Gabal Oshkafa area are important targets for gold exploration due to their association with quartz veins, mineral alterations, and diverse structural styles. Orogenic lode gold deposits and placer gold occurrences have been identified, with variations in gold (0 – 0.84 ppm) and silver (0 – 25.3 ppm) values. The pressure-temperature conditions during ore formation influenced vein textures and alteration patterns. Gold is found as lattice-bound solid solutions within sulfides, nano-particles and visible grains.
The Elba manganese deposits occur in Oshbia, El-Hebal, N-Gabal Toyo, Mateet, Adeeb, Blownay, Sirmatai, Sarara, Aqilahuq, Eikwan, N-Wadi Ajway and Wadi Bashoya. Geochemistry of Mn ores suggests chemical precipitation from hydrothermal solutions, while the presence of oolites and colloform textures in the mangneferous types indicates re-deposition through sedimentation processes. Their MnO contents vary between 3.28 and 61.02 wt.%.
The Sol-Hamed area contains cryptocrystalline deposits of magnesite, characterized by white patches with vertical veins and horizontal sheets. Analysis of the magnesite ore indicates an average MgO contents of (42.98 wt.%) and low Fe2O3 levels (average of 0.08 wt.%). This proposes that the hydrothermal solutions accountable for carbonation were deficient in iron and that the predominant carbonate mineral present is magnesite.