Manganese Mineralization Related to the Red Sea Rift System: Examples from the Red Sea Coast and Sinai, Egypt

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Manganese or ferro-manganese mineralizations occur along the western Red Sea coastal zone and Sinai, Egypt. Their occurrence and distribution patterns are closely associated with the Red Sea rifting. The Halaib area and Wadi Araba in the Eastern Desert, and Sharm El Sheikh and Um Zariq areas in South Sinai represent the hydrothermal manganese deposits along the Red Sea coast. These deposits occur as veins and fracture filling cutting across the structure of the host rocks (Paleozoic, Miocene and Plio-Pleistocene sedimentary rocks, Precambrian granite and volcanic rocks), indicating the epigenetic origin. The mineral forming associations are typical for hydrothermal Mn deposits. This mineralization is characterized by enrichment in Tl, Mo, Zn, Cu, Sr, Ba, Pb and U. The REE patterns are characterized by negative to no Ce-and negative Eu-anomalies. The high Tl and Mo contents, U/Th ratios and REE patterns provide a firm evidence for a hydrothermal origin, related to Red Sea rifting. The Miocene Mn deposits of the Abu Shaar area on the Red Sea coast are formed by diagenetic replacement of the calcitic materials by Mn-bearing solutions during a marine transgression-regression. Based on petrographic and texture evidence (i.e., graded pisoliths and ooliths accumulation), characteristic mineral-chemical enrichment and geochemical association (low Tl, Zn, U, Th, low REE budget and positive Ce-anomaly) indicate a marine-diagenetic origin.