Au-Cu Resources in Some Mines from Antiquity in the South Gabal Um Monqul and Gabal Al Kharaza Prospects, North Eastern Desert, Egypt
Since Antiquity, sustainable resources of gold and copper have been mined at two prominent prospects in the north Eastern Desert of Egypt, namely the south Gabel Um Monqul (SGUM) and Gabal Al Kharaza (GKZ). Mineralization is hosted by Neoproterozoic shield rocks represented by dacite and monzo- to s...
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MDPI AG
2023-09-01
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| author | Abdallah Atef Adel A. Surour Ahmed A. Madani Mokhles K. Azer |
| author_facet | Abdallah Atef Adel A. Surour Ahmed A. Madani Mokhles K. Azer |
| author_sort | Abdallah Atef |
| collection | DOAJ |
| description | Since Antiquity, sustainable resources of gold and copper have been mined at two prominent prospects in the north Eastern Desert of Egypt, namely the south Gabel Um Monqul (SGUM) and Gabal Al Kharaza (GKZ). Mineralization is hosted by Neoproterozoic shield rocks represented by dacite and monzo- to syenogranite at the SGUM prospect whereas they are diorite, granodiorite, and quartz feldspar porphyry at the GKZ prospect. These hosts have been emplaced in an island arc environment from calc-alkaline magmas with a peraluminous to metaluminous signature. They are hydrothermally altered including albitization, sericitization, silicification, epidotization, and chloritization. The Au and Cu mineralizations are confined to shear zones that lately filled with auriferous quartz veins adjacent to mineralized alteration zones. In the GKZ prospect, the old trenches trend mainly in a NW–SE direction whereas it is NE–SW and NW–SE in the SGUM prospect. Evidence of shearing ranges from megascopic conjugate fractures and shear planes in the outcrops to microscopic sheared and crumbled Au-Cu ore assemblages dominated by Fe-Cu sulfides, specularite, and barite. Microscopic investigation suggests that the formation of specularite is due to the shearing of early existing magnetite. The ore textures and paragenetic sequence indicate that pyrite in the alteration zones is oxidized, leading to the liberation of gold up to 3.3 g/t. The formulae of the analyzed electrum lie in the range Au<sub>74.5-76.8</sub> Ag<sub>22.2-24.5</sub>. Integration of the field, geochemistry, and mineral chemistry data, combined with the gold fire assay data prove the presence of sustainable amounts of disseminated Au and Cu, not only in the mineralized quartz veins, but also in the alteration zones. Data materialized in our paper show similarities in the style of mineralization at the SGUM and the GKZ prospects with iron oxide-copper-gold (IOCG) deposits elsewhere in the Arabian-Nubian Shield (ANS) and other world examples. |
| first_indexed | 2024-03-10T22:43:32Z |
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| language | English |
| last_indexed | 2024-03-10T22:43:32Z |
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| spelling | doaj.art-8a7f675883564f548017c0f1d47e03df2023-11-19T10:55:00ZengMDPI AGGeosciences2076-32632023-09-0113928310.3390/geosciences13090283Au-Cu Resources in Some Mines from Antiquity in the South Gabal Um Monqul and Gabal Al Kharaza Prospects, North Eastern Desert, EgyptAbdallah Atef0Adel A. Surour1Ahmed A. Madani2Mokhles K. Azer3Department of Geology, Faculty of Science, Cairo University, Giza 12613, EgyptDepartment of Geology, Faculty of Science, Cairo University, Giza 12613, EgyptDepartment of Geology, Faculty of Science, Cairo University, Giza 12613, EgyptGeological Sciences Department, National Research Centre, Giza 12622, EgyptSince Antiquity, sustainable resources of gold and copper have been mined at two prominent prospects in the north Eastern Desert of Egypt, namely the south Gabel Um Monqul (SGUM) and Gabal Al Kharaza (GKZ). Mineralization is hosted by Neoproterozoic shield rocks represented by dacite and monzo- to syenogranite at the SGUM prospect whereas they are diorite, granodiorite, and quartz feldspar porphyry at the GKZ prospect. These hosts have been emplaced in an island arc environment from calc-alkaline magmas with a peraluminous to metaluminous signature. They are hydrothermally altered including albitization, sericitization, silicification, epidotization, and chloritization. The Au and Cu mineralizations are confined to shear zones that lately filled with auriferous quartz veins adjacent to mineralized alteration zones. In the GKZ prospect, the old trenches trend mainly in a NW–SE direction whereas it is NE–SW and NW–SE in the SGUM prospect. Evidence of shearing ranges from megascopic conjugate fractures and shear planes in the outcrops to microscopic sheared and crumbled Au-Cu ore assemblages dominated by Fe-Cu sulfides, specularite, and barite. Microscopic investigation suggests that the formation of specularite is due to the shearing of early existing magnetite. The ore textures and paragenetic sequence indicate that pyrite in the alteration zones is oxidized, leading to the liberation of gold up to 3.3 g/t. The formulae of the analyzed electrum lie in the range Au<sub>74.5-76.8</sub> Ag<sub>22.2-24.5</sub>. Integration of the field, geochemistry, and mineral chemistry data, combined with the gold fire assay data prove the presence of sustainable amounts of disseminated Au and Cu, not only in the mineralized quartz veins, but also in the alteration zones. Data materialized in our paper show similarities in the style of mineralization at the SGUM and the GKZ prospects with iron oxide-copper-gold (IOCG) deposits elsewhere in the Arabian-Nubian Shield (ANS) and other world examples.https://www.mdpi.com/2076-3263/13/9/283sustainable Au-Cu resourcesalteration zoneshear zoneIOCGnorth Eastern DesertEgypt |
| spellingShingle | Abdallah Atef Adel A. Surour Ahmed A. Madani Mokhles K. Azer Au-Cu Resources in Some Mines from Antiquity in the South Gabal Um Monqul and Gabal Al Kharaza Prospects, North Eastern Desert, Egypt Geosciences sustainable Au-Cu resources alteration zone shear zone IOCG north Eastern Desert Egypt |
| title | Au-Cu Resources in Some Mines from Antiquity in the South Gabal Um Monqul and Gabal Al Kharaza Prospects, North Eastern Desert, Egypt |
| title_full | Au-Cu Resources in Some Mines from Antiquity in the South Gabal Um Monqul and Gabal Al Kharaza Prospects, North Eastern Desert, Egypt |
| title_fullStr | Au-Cu Resources in Some Mines from Antiquity in the South Gabal Um Monqul and Gabal Al Kharaza Prospects, North Eastern Desert, Egypt |
| title_full_unstemmed | Au-Cu Resources in Some Mines from Antiquity in the South Gabal Um Monqul and Gabal Al Kharaza Prospects, North Eastern Desert, Egypt |
| title_short | Au-Cu Resources in Some Mines from Antiquity in the South Gabal Um Monqul and Gabal Al Kharaza Prospects, North Eastern Desert, Egypt |
| title_sort | au cu resources in some mines from antiquity in the south gabal um monqul and gabal al kharaza prospects north eastern desert egypt |
| topic | sustainable Au-Cu resources alteration zone shear zone IOCG north Eastern Desert Egypt |
| url | https://www.mdpi.com/2076-3263/13/9/283 |
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