Orogenic Gold Deposits in Egypt
摘要
The orogenic gold deposits in Egypt, especially within the Eastern Desert, hold a long history of mining but remain underexplored by modern techniques. The chapter “Orogenic Gold Deposits in Egypt” delves into the genesis, classification, and economic potential of these deposits, emphasizing the need for innovative exploration techniques. Formed during the Neoproterozoic era and intimately linked to tectonic processes of the Pan-African orogeny, these deposits are associated with major faults and shear zones, such as the Najd Fault System, which provided the pathways for gold-bearing hydrothermal fluids. Key alteration processes, including sulfidation, silicification, and sericitization, with minor carbonatization and chloritization, often accompany quartz vein formation, serving as vital indicators of mineralization. The chapter presents a detailed genetic model where gold was deposited at varying depths of 3–15 km, driven by interactions between hydrothermal fluids, granitoid intrusions, and surrounding metamorphosed rocks. Deposits are further classified into epizonal, mesozonal, and hypozonal types, each defined by varying depths of formation and structural characteristics. Additionally, differences in styles and mineral assemblages based on geodynamic environment characterize greenstone-hosted, turbidite-hosted, carbonate rock-hosted, and hypabyssal intrusion-hosted deposits, offer a broader perspective on the geological processes involved. Also, an atypical orogenic gold deposit type formed under distinct transitional conditions combines features of epithermal, mesozonal orogenic, and porphyry systems. This hybrid deposit type creates a unique mineralization style, setting the ores apart from those of conventional orogenic deposits. Given the considerable untapped potential, particularly in the Eastern Desert, the chapter stresses the importance of advanced exploration techniques such as remote sensing, GIS, and isotopic analysis to better map structural controls and ore-forming systems. The economic promise of these deposits is underscored by the success of modern mining operations like those at the Sukari deposit, highlighting the need for more refined exploration approaches and sustainable mining practices. With such strategies, Egypt’s orogenic gold deposits could play a transformative role in both the country’s economy and the global gold mining industry.