Transpressional imbricate thrust zones controlling gold mineralization in the Central Eastern Desert of Egypt |
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| Institution: | 1. Geology Department, Faculty of Science, Tanta University, Tanta 31527, Egypt;2. Centamin Egypt Ltd, 361 El-Horreya Road, Sedi Gaber, Alexandria, Egypt;1. Université de Toulouse, CNRS, Géosciences Environnement Toulouse, Institut de Recherche pour le Développement, Observatoire Midi-Pyrénées, 14 Av. Edouard Belin, F-31400 Toulouse, France;2. Azumah Resources Ghana Limited, PMB CT452, Cantonments, Accra, Ghana;3. IFAN Cheikh Anta Diop, Dakar, Senegal;4. ONG-D “Le Soleil dans la Main” asbl, 48, Duerfstrooss, L-9696 Winseler, Luxembourg;5. University of Ghana, Department of Earth Sciences, P.O. Box LG 58, Legon, Accra, Ghana;6. Centre for Exploration Targeting, School of Earth and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia;1. School of Geosciences, University of Sydney, NSW 2006, Australia;2. Bare Rock Geological Services Pty Ltd, Fremantle, WA 6160, Australia;3. School of Earth Sciences, University of Western Australia, Crawley, WA 6009, Australia;4. Geology Department, Lakehead University, 955 Oliver Rd, Thunder Bay, Ontario, P7B 5E1, Canada |
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| Abstract: | Strongly deformed volcaniclastic metasediments and ophiolitic slices hosting the Sukari gold mineralization display evidence of a complex structural evolution involving three main ductile deformational events (D1–D3). D1 produced ENE-trending folds associated with NNW-propagating thrust slices and intrusion of the Sukari granite (689 ± 3 Ma). D2 formed a moderately to steeply dipping, NNW-trending S2 foliation curved to NE and developed arcuate structure constituting the Kurdeman shear zone (≤ 595 Ma) and East Sukari imbricate thrust belt. Major NE-trending F2 folds, NW-dipping high-angle thrusts, shallow and steeply plunging mineral lineation and shear indicators recorded both subhorizontal and subvertical transport direction during D2. D3 (560–540 Ma) formed NNE-trending S3 crenulation cleavage, tight F3 folds, Sukari Thrust and West Sukari imbricate thrust. The system of NW-trending sinistral Kurdeman shear zone (lateral ramps and tear faults) and imbricate thrusts (frontal ramps) forming the actuate structure developed during SE-directed thrusting, whereas the prevailing pattern of NNE-trending dextral Sukari shear zone and imbricate thrusts forming Sukari thrust duplex developed during NE-directed tectonic shearing. Sukari granite intruded in different pluses between 689 and 540 Ma and associated with at least four phases of quartz veins with different geometry and orientation. Structural analysis of the shear fabrics indicates that the geometry of the mineralized quartz veins and alteration patterns are controlled by the regional NNW- and NE-trending conjugate zones of transpression. Gold-bearing quartz veins are located within NNW-oriented sinistral shear zones in Kurdeman gold mine area, within steeply dipping NW- and SE dipping thrusts and NE- and NS-oriented dextral and sinistral shear zones around Sukari mine area, and along E-dipping backthrusts and NW-SE and N-S fractures in Sukari granite. The high grade of gold mineralization in Sukari is mainly controlled by SE-dipping back-thrusts branched from the major NW-dipping Sukari Thrust. The gold mineralization in Sukari gold mine and neighboring areas in the Central Eastern Desert of Egypt is mainly controlled by the conjugate shear zones of the Najd Fault System and related to E-W directed shortening associated with oblique convergence between East and West Gondwana. |
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