GENETIC AFFILIATION OF GOLD AND URANIUM MINERALIZATION IN EL-MISSIKAT GRANITE, CENTRAL EASTERN DESERT, EGYPT | ||||
| Nuclear Sciences Scientific Journal | ||||
| Article 3, Volume 5, Issue 1, 2016, Page 33-47 PDF (3.54 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/nssj.2016.30823 | ||||
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| Authors | ||||
| FATHY A. AMMAR; SAYED A. M. OMAR; EL SAYED H. EL SAWEY | ||||
| Nuclear Materials Authority,Cairo, Egypt | ||||
| Abstract | ||||
| Gabal El-Missikat granitic pluton is affected by two fault systems trending NW-SE (the oldest) and ENE-WSW directions. It is one of the uranium occurrences in the Eastern Desert of Egypt. The northwestern margins of El-Missikat pluton, along its contact with the gneissose quartz diorite, are dissected by numerous reactivated fractured shear zones running generally ENE-WSW to NE-SW and dipping about 600-700 to SE. Many white (oldest), smoky or black and jasperoid (youngest) silica veinlets fill the fractures of these shear zones. These veins are of irregular shape and variable thickness ranging from few centimeters to about three meters. They are chiefly affected by silicification, sericitization, hematitization , kaolinization and hydrothermal alterations processes. The smoky black veins are hosting secondary uranium and fluorite-, sulphide-gold mineralizations. Polished surface studies, ICP-ES and Atomic Absorption as well as Scanning Electron Microscope measurements recorded galena, pyrite chalcopyrite, sphaleriteand molybdenite in the black and jasperoid mineralized veins. Gold associated with ore mineral assemblage as pyrite, chalcopyrite, sphalerite, galena, sheelite and iron oxides. The identified sulphide minerals not bearing gold are recorded. Gold are relatively coarse-grained, massive and metallic yellow or stretched bronze colored particles. The recorded secondary U minerals associates the sulphide gold-mineralization in the black and jasperoid silica veins. Regarding the mobility of both uranium and gold, U4+mobilized in oxidizing medium and migrate and transport as U6+, then deposited later as U4+ when the medium changes to be reducing characterized by high ƒO2 . On contrary, gold mobilized when the medium is complex AuCl3- ion bearing. Consequently, El- Missikat granitic pluton affected by oxidizing Au and Cl3- bearing high temperature hydrothermal solutions that leached U4+, W and Mo from the granitic mass as U6+, later decrease of temperature, both U and gold deposited as well as the sulphide minerals of Pb, Zn, cu, Fe and Mo in the high temperature hydrothermal fluids were deposited with increase of S+2 ion. | ||||
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