Metallogenic evolution of uranium deposits in the Middle East and North Africa deposits

Howari, Fares M.; Goodell, Philip C.; Salman, Abdel Aty B.

doi:10.1016/j.jafrearsci.2015.11.009

Cited by 10 publications

(1 citation statement)

References 14 publications

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“…Gold deposits occur either as stratabound formed due to exhalative hydrothermal processes during the last stages of sub-marine volcanic activity in island arcs 8 , 9 , vein-type 10 , 11 , disseminated –type in altered rocks 12 or as placers 13 . The main uranium occurrences are found in shear zones in the Pan-African late orogenic granite and related rocks 14 , alkaline dykes and sills 15 , Phanerozoic sedimentary rocks 16 , 17 and beach placers of the black sand 18 . However, due to their considerable chemical favorability for infiltration by hydrothermal fluids, carbonate rocks are a well-known host for various types of hydrothermal alteration and metasomatism-related mineralization including gold 19 – 21 , uranium 22 – 25 , and rare earth elements 26 , 27 .…”

Section: Introductionmentioning

confidence: 99%

Multiscale (microscopic to remote sensing) preliminary exploration of auriferous-uraniferous marbles: A case study from the Egyptian Nubian Shield

Shebl

Hamdy

2023

Sci Rep

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Since their recent first record within the Egyptian Nubian Shield, auriferous and uraniferous marbles (Au = 0.98–2.76 g/t; U = 133–640 g/t) have rarely been addressed, despite not only their probable economic importance but also the fact that it is a new genetic style of gold and uranium mineralization in the Nubian Shield rocks. This is mainly attributed to the inadequate localization of these marbles within harsh terrains, as well as the cost and time spent with conventional fieldwork for their identification compared to the main lithological components of the Nubian Shield. On the contrary, remote sensing and machine learning techniques save time and effort while introducing reliable feature identification with reasonable accuracy. Consequently, the current research is an attempt to apply the well-known machine learning algorithm (Support vector Machine—SVM) over Sentinel 2 remote sensing data (with a spatial resolution of up to 10 m) to delineate the distribution of auriferous-uraniferous marbles in the Barramiya-Daghbagh district (Eastern Desert of Egypt), as a case study from the Nubian Shield. Towards better results, marbles were accurately distinguished utilizing ALOS PRISM (2.5 m) pan-sharpened Sentinel 2 data and well-known exposures during fieldwork. With an overall accuracy of more than 90%, a thematic map for auriferous-uraniferous marbles and the major rock units in the Barramiya-Daghbagh district was produced. Marbles are spatially related to ophiolitic serpentinite rocks, as consistent with their genesis within the Neoproterozoic oceanic lithosphere. Field and petrographic investigations have confirmed the newly detected Au and U-bearing zones (impure calcitic to impure dolomitic marbles in Wadi Al Barramiya and Wadi Daghbagh areas and impure calcitic marble in Gebel El-Rukham area). Additionally, X-ray diffraction (XRD), back-scattered electron images (BSEIs), and Energy Dispersive X-ray spectroscopy (EDX) results were integrated to verify our remote sensing results and petrographic investigations. Different times of mineralization are indicated, ranging from syn-metamorphism (gold in Wadi Al Barramiya and Gebel El-Rukham) to post-metamorphism (gold in Wadi Daghbagh and uranium in all locations). Based on the application of geological, mineralogical, machine learning and remote sensing results for the construction of a preliminary exploration model of the auriferous-uraniferous marble in the Egyptian Nubian Shield, we recommend a detailed exploration of Au and U-bearing zones in Barramiya-Dghbagh district and applying the adopted approach to other districts of similar geological environments.

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Section: Introductionmentioning

confidence: 99%

Multiscale (microscopic to remote sensing) preliminary exploration of auriferous-uraniferous marbles: A case study from the Egyptian Nubian Shield

Shebl

Hamdy

2023

Sci Rep

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Metallic Ores in North Africa: New Results and Achievements in the Post-2016 Era

Surour

2024

Regional Geology Reviews

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Tracking of uranium and thorium natural distribution in the chemical fractions of the Nile Valley and the Red Sea phosphorites, Egypt

Aita,

Abdel-Azeem,

Abu Khoziem

et al. 2024

Carbonates Evaporites

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The present study aims to elucidate the possible sources of uranium and thorium content in the Campanian–Maastrichtian phosphorites from the Duwi Formation in the Nile Valley and Red Sea by conducting facies analysis and sequential leaching method. Nile Valley samples were collected from the El-Sibaiya East area, while those of the Red Sea were collected from two locations: Hamadat and Zug El Bahar. The petrographic investigation revealed that the Sibaiya East phosphorites exhibit peloidal bioclastic phospharenite–phospharudite microfacies, while Hamadat and Zug El Bahar phosphorites display peloidal bioclastic phosphalutite and silicified peloidal bioclastic phospharenite microfacies, respectively. Besides, U–Th bearing accessory minerals, such as zircon and monazite occur in Sibaiya East phosphorites. Thorium is present in Zug El Bahar phosphorites as minute accumulations associating apatite and quartz. Moreover, uranium is found with vanadium and iron as fine patches in the Sibaiya East phosphorite, and as small disseminations associated with Ca and Si in the Hamadat phosphorite. The X-ray diffraction shows that the investigated phosphorites are essentially built up of hydroxyl apatite Ca5(PO4)3(OH) and quartz SiO2. To accurately evaluate the bioavailability and mobility of uranium and thorium in the investigated phosphorites, it was necessary to identify the overall concentration and the various chemical forms of these elements by a five-step sequential leaching technique. The results indicate that Th and U are more abundant in the Red Sea phosphorites than in the Nile Valley phosphorites. Furthermore, Th is not bio-available and it is mostly found in the residue as Th-bearing minerals. Uranium, unlike Th is bio-available and fractionates among all fractions, indicating that U accumulation is the result of various diagenetic processes.

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Metallogenic evolution of uranium deposits in the Middle East and North Africa deposits

Cited by 10 publications

References 14 publications

Multiscale (microscopic to remote sensing) preliminary exploration of auriferous-uraniferous marbles: A case study from the Egyptian Nubian Shield

Multiscale (microscopic to remote sensing) preliminary exploration of auriferous-uraniferous marbles: A case study from the Egyptian Nubian Shield

Metallic Ores in North Africa: New Results and Achievements in the Post-2016 Era

Tracking of uranium and thorium natural distribution in the chemical fractions of the Nile Valley and the Red Sea phosphorites, Egypt

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