Controls on lode gold mineralization, Romite deposit, South Eastern Desert, Egypt

Zoheir, Basem

doi:10.1016/j.gsf.2012.03.003

Cited by 21 publications

(10 citation statements)

References 46 publications

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“…Serpentinite and talc-carbonate rocks form large NW-SE-trending elongated masses. Moreover, small elongated slices (<100 m) of highly sheared serpentinite and talc-carbonate schist are tectonically incorporated within the island arc-metavolcanic/volcaniclastic terrains [1, 39,40]. The island arc-metavolcanic/volcaniclastic assemblages form NNW-SSE-and NW-SE-trending belts of highly foliated and sheared basic-intermediate to acidic metavolcanic/volcaniclastic rocks [39][40][41][42].…”

Section: Geologic Settingmentioning

confidence: 99%

Multispectral and Radar Data for the Setting of Gold Mineralization in the South Eastern Desert, Egypt

et al. 2019

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Satellite-based multi-sensor data coupled with field and microscopic investigations are used to unravel the setting and controls of gold mineralization in the Wadi Beitan–Wadi Rahaba area in the South Eastern Desert of Egypt. The satellite-based multispectral and Synthetic Aperture Radar (SAR) data promoted a vibrant litho-tectonic understanding and abetted in assessing the regional structural control of the scattered gold occurrences in the study area. The herein detailed approach includes band rationing, principal component and independent component analyses, directional filtering, and automated and semi-automated lineament extraction techniques to Landsat 8- Operational Land Imager (OLI), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Phased Array L-band Synthetic Aperture Radar (PALSAR), and Sentinel-1B data. Results of optical and SAR data processed as grayscale raster images of band ratios, Relative Absorption Band Depth (RBD), and (mafic–carbonate–hydrous) mineralogical indices are used to extract the representative pixels (regions of interest). The extracted pixels are then converted to vector shape files and are finally imported into the ArcMap environment. Similarly, manually and automatically extracted lineaments are merged with the band ratios and mineralogical indices vector layers. The data fusion approach used herein reveals no particular spatial association between gold occurrences and certain lithological units, but shows a preferential distribution of gold–quartz veins in zones of chlorite–epidote alteration overlapping with high-density intersections of lineaments. Structural features including en-echelon arrays of quartz veins and intense recrystallization and sub-grain development textures are consistent with vein formation and gold deposition syn-kinematic with the host shear zones. The mineralized, central-shear quartz veins, and the associated strong stretching lineation affirm vein formation amid stress build-up and stress relaxation of an enduring oblique convergence (assigned as Najd-related sinistral transpression; ~640–610 Ma). As the main outcome of this research, we present a priority map with zones defined as high potential targets for undiscovered gold resources.

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Section: Geologic Settingmentioning

confidence: 99%

Multispectral and Radar Data for the Setting of Gold Mineralization in the South Eastern Desert, Egypt

et al. 2019

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“…Gold, grading as much as 7 g/t Au, occurs as free grains in north-northeast-trending quartz and quartzcarbonate veins in quartz diorite and as disseminations in ironstained, carbonate-altered and silicified wall rock. Sulfides in the veins include pyrite, arsenopyrite, and lesser chalcopyrite and pyrrhotite (Zoheir, 2012b). The morphology, pinch and swell structure, and quartz texture of the veins suggest vein formation was synkinematic with north-northeast-shearing (Zoheir, 2012b) and it appears that quartz precipitated in spaces created at releasing bends in the shears.…”

Section: Orogenic Goldmentioning

confidence: 96%

“…Exploration is underway elsewhere along the Keraf suture at the Galat Sufa, Negeim, Kimaweit, Artoli, and Umtrambiesh prospects, and along the Nakasib suture at Kamoeb. The Romite deposit (Zoheir, 2012b) is an example of orogenic gold in the structurally complex area east of the intersection of the Allaqi-Heinai-Onib-Sol Hamed suture by the Hamisana shear zone (Figure 4). It is located in a northnortheast-trending sinistral shear zone that splays off the Hamisana shear zone.…”

Section: Orogenic Goldmentioning

confidence: 99%

Gold-bearing volcanogenic massive sulfides and orogenic-gold deposits in the Nubian Shield

Johnson¹,

Zoheir

Ghebreab

et al. 2017

South African Journal of Geology

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The Nubian Shield is a large region of juvenile Neoproterozoic rocks that, together with its counterpart in the Arabian Shield, is part of a major accretionary orogen. It originated as late Tonian-Cryogenian island arcs on the site of the Mozambique Ocean formed by breakup of Rodinia. Arc collisions, subsequent magmatism, volcanism, sedimentation, and orogeny, associated with Cryogenian-Ediacaran convergence of cratonic blocks during the assembly of Gondwana, converted the region into the East African Orogen. The Nubian Shield region also has important Paleozoic-Neogene strata, including significant flood basalt, that conceal large areas of the basement. The Shield contains hundreds of gold occurrences and evidence of a 5,500-year history of gold mining. The main deposit types are orogenic gold and gold associated with volcanogenic massive sulfides (VMS). The juvenile subduction-related origin of the Shield rocks and the pervasiveness of shearing and greenschist-to-amphibolite facies metamorphism associated with late Neoproterozoic orogeny are geologic features highly favorable for the development of these types of deposits, and make the combined Arabian-Nubian Shield the Earth's largest Neoproterozoic gold resource. Gold-bearing VMS deposits are currently mined at Bisha (Eritrea) and are soon to be

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“…(a) δ 13 C vs. δ 18 O, (b) δ 13 C vs. 87 Sr/ 86 Sr at ~ 600 Ma. Fields and references displayed are: MR= mantle/magmatic rocks (Zheng and Hoefs 1993), OB = oceanic basalt (Kyser 1986), DM= Depleted mantle, intrusive carbonatite field (Taylor et al 1967;Deines 1989), IGC = igneous calcite (Ray et al 2000), RQC = Au-quartz carbonate veins from the Romite deposit (Zoheir 2012). The isotopic compositional range of three gold deposits in the South Eastern Desert is the broken line ellipsoid.…”

Section: Genetic Model and Key Criteria For Exploration In The Areamentioning

confidence: 99%

Trace elements and isotope data of the Um Garayat gold deposit, Wadi Allaqi district, Egypt

et al. 2018

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Trace element composition of sulfides and O, C, Sr and S isotopic data are assessed to constrain the evolution and potential fluid and metal sources of the Um Garayat gold deposit. Ore microscopy and BSE investigations of quartz veins show blocky arsenopyrite and pyrite replaced in part by pyrrhotite, chalcopyrite, sphalerite, galena, and gersdorffite. Free-milling gold occurs commonly in close association with the late sulfides, and along fractures in pyrite. On the other hand, recrystallized pyrite is disseminated in host metavolcaniclastic/metasedimentary rocks that commonly contain carbonaceous material. In-situ LA-ICP-MS analysis of sulfides show the recrystallized pyrite enriched in most trace elements, while blocky pyrite contains only some traces of arsenic. Detected concentrations of gold (up to 17 ppm) were only reported in arsenopyrite disseminated in quartz veins. The δ 34 S values of blocky pyrite and pyrrhotite in quartz veins define a narrow range (1.6 to 3.7 ‰), suggesting a homogenous sulfur source which is consistent with the dominantly mafic host rocks. The recrystallized pyrite has a distinctive sulfur isotope composition (δ 34 S-9.3 to-10.6 ‰), which is rather comparable to diagenetic sulfides. Hydrothermal carbonate in quartz veins and wallrock have nearly constant values of δ 18 O (10.5 to 11.9 ‰) and δ 13 C (-4.2 to-5.5‰). Based on constraints from mineral assemblages and chlorite thermometry, data of six samples indicate that carbonate precipitation occurred at ~280°C from a homogenous hydrothermal fluid with δ 18 OH2O 4.4±0.7‰ and δ 13 C =-3.7 ± 0.8 ‰. Strontium isotope values of two samples (87 Sr/ 86 Sr = 0.7024 and 0.7025) are similar to the initial 87 Sr/ 86 Sr ratios of island arc metabasalts (~710 Ma) in the South Eastern Desert. The generally homogenous sulfur, C, O, Sr isotope data are suggestive of metamorphogenic fluids, likely produced from dominantly mafic volcanic rocks at the greenschist-amphibolite facies transition.

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Controls on lode gold mineralization, Romite deposit, South Eastern Desert, Egypt

Cited by 21 publications

References 46 publications

Multispectral and Radar Data for the Setting of Gold Mineralization in the South Eastern Desert, Egypt

Multispectral and Radar Data for the Setting of Gold Mineralization in the South Eastern Desert, Egypt

Gold-bearing volcanogenic massive sulfides and orogenic-gold deposits in the Nubian Shield

Trace elements and isotope data of the Um Garayat gold deposit, Wadi Allaqi district, Egypt

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