Gold occurrences in the Eastern Desert of Egypt have different styles of mineralization that reflect various tectonic settings and/or specific events during the crustal evolution of the Nubian Shield (NS). The crystalline basement rocks of the Egyptian segment host the majority of the primary gold deposits including (IRG/Porphyry, Orogenic type, VMS-related gold), as well as Placer-gold type. The IRG type is linked with late-to post-collision magmatic intrusion (younger granite, gabbro) or Dokhan volcanics that has been observed in some localities (ex: Um Monqul, Um Balad, Abu Dabbab, Atud). The orogenic-gold type is confined to Late arc-continent terrains (~635–540 Ma), formed during the second orogenic event that was responsible for the NNW-SSE Najd Fault System (NFS) and N-S Hamisana Shear Zone. It is well-presented at many localities in Egypt (ex: Atalla, Gidami, Fawakheir, Sukari, Haimur). Some gold deposits (ex: Fatira gold) show combined characteristics reflecting a transition between IRG and orogenic types (hybrid magmatic-metamorphic origin). VMS-related gold in Egypt is categorized into; (1) Auriferous VMS-related island arc volcanics and associated volcanoclastic rocks (Semna, Um Samuki, Darhib), (2) Gold-hosted in Banded Iron Formation (ex: Abu Marawat), and (3) Gossan-related gold type overlying a burred sulfides ore (ex: Hamama). The placer-gold type represents secondary gold deposits, where the gold is found in the modern alluvial sediments that are commonly nearby major primary occurrences (ex: El Sid, Sukari, Umm Ud), or it could also be detected within paleoplacer conglomerates at the base of Nubian Sandstone Formation (ex: hammamat deposits).

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An Overview for Gold Mineralization in the Egyptian Segment of the Northern Continuation of the East African Orogen

  • Mohamed Abd El Monsef

摘要

Gold occurrences in the Eastern Desert of Egypt have different styles of mineralization that reflect various tectonic settings and/or specific events during the crustal evolution of the Nubian Shield (NS). The crystalline basement rocks of the Egyptian segment host the majority of the primary gold deposits including (IRG/Porphyry, Orogenic type, VMS-related gold), as well as Placer-gold type. The IRG type is linked with late-to post-collision magmatic intrusion (younger granite, gabbro) or Dokhan volcanics that has been observed in some localities (ex: Um Monqul, Um Balad, Abu Dabbab, Atud). The orogenic-gold type is confined to Late arc-continent terrains (~635–540 Ma), formed during the second orogenic event that was responsible for the NNW-SSE Najd Fault System (NFS) and N-S Hamisana Shear Zone. It is well-presented at many localities in Egypt (ex: Atalla, Gidami, Fawakheir, Sukari, Haimur). Some gold deposits (ex: Fatira gold) show combined characteristics reflecting a transition between IRG and orogenic types (hybrid magmatic-metamorphic origin). VMS-related gold in Egypt is categorized into; (1) Auriferous VMS-related island arc volcanics and associated volcanoclastic rocks (Semna, Um Samuki, Darhib), (2) Gold-hosted in Banded Iron Formation (ex: Abu Marawat), and (3) Gossan-related gold type overlying a burred sulfides ore (ex: Hamama). The placer-gold type represents secondary gold deposits, where the gold is found in the modern alluvial sediments that are commonly nearby major primary occurrences (ex: El Sid, Sukari, Umm Ud), or it could also be detected within paleoplacer conglomerates at the base of Nubian Sandstone Formation (ex: hammamat deposits).