Intrusion‐related Gold Deposits in Egypt

Abstract

Intrusion‐related gold deposits (IRGDs) occur in the Eastern Desert (ED) of Egypt within magmatic districts that are exploited for tungsten and tin mineralization. IRGDs and intrusion‐related rare metal deposits (IRRMDs) are almost invariably linked with the late to post collisional Younger Granites (YGs) that have three successive phases (I, II and III). At ∼635–630 Ma, the ED underwent a transition in deformation style from compressional to extensional and a switch from subduction with crustal thickening to delamination with crustal thinning. This transition was concurrent with the emplacement of a short magmatic pulse (∼635–630 Ma) that represents a transition between orogenic gold deposits and IRGDs. K‐rich calc alkaline granites (phase I and II of the YGs) hosting IRGDs like the Hangalia deposit were emplaced during the time span 630–610 Ma. Alkaline magmatism began at 610 Ma, coexisting with the K‐rich calc‐alkaline magmatism over the 610–590 Ma time span, where the Fawakhir (598 ± 3 Ma) and Um Had (596 ± 2 Ma) granites that host the IRGDs were emplaced. In time, the alkaline magmatism became more alkaline giving rise to phase III of the YGs that hosts IRRMDs. A distinct metallogenic epoch comprising both IRGDs and IRRMDs, was undergoing extreme growth at ∼600 Ma.

Intrusion-related Low Sulphidation Gold Mineralization, Wadi Hammad Area, North Eastern Desert, Egypt

“…Four main types of mineralization styles are recognized they are; 1-mineralized quartz vein, 2-hydrothermal wall rock alteration, and 3breccia. The geological studies indicate that the present mineralization belongs to the intrusion-related gold deposits [4]. Generally, the hydrothermal deposits have relatively low Ni/Cr ratios owing to the higher solubility of Ni with respect to Cr in hydrothermal fluids [27].…”

“…Intrusion-related gold deposits in the Eastern Desert of Egypt are represented by Au-bearing quartz veins and/or hydrothermally altered zones hosted within (1) post-collisional granites or in the contact with (2) younger gabbros, (3) Dokhan volcanic, (4) Hammamat sediments, (5) ophiolitic serpentinites, and (6) island arc assemblages and ophiolitic mélange. The majority of these mineralizations are widely distributed in the Central and Southern Eastern Desert of Egypt, whereas their occurrences in the Northern Eastern Desert are very limited and poorly studied [4].…”

Magmatism and Related Mineralizations in Wadi Hammad, North Eastern Desert, Egypt

“…Porphyry-Cu and epithermal deposits are genetically associated with arc magmas displaying a broad range of compositions, from low-K calc-alkaline, through high-K calc-alkaline, to alkaline (e.g., [2-4]. In the North Eastern Desert of Egypt, granitoids and their related mineral deposits (particularly Sn-W-Ta-Mo-U-REE mineralization [5], porphyry Cu-Mo-Au (Um Monqul porphyry located to the north of the study area) [6] and hydrothermal vein-type gold [7], are showing coeval association. On the other hand, a special association between adakites and of large number of porphyry and epithermal deposits has been provided by many authors [8-10].…”