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Bahariya, Aswan districts - El Gedida, Gebel Ghorabi |
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Egypt |
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Fe
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Bahariya Oasis iron deposits are located approximately 329 km to the SW of Cairo in central western Egypt within an exposed Upper Cretaceous to Eocene succession.
The immediate host sequence at Bahariya Oasis was deposited in a fluvial-deltaic coastal plain, lagoonal, estuarine and shallow marine environments. It commences with a lower, 80 m thick unit of Eocene chalky limestone and marls; overlain by up to 170 m of shales grading up into siltstones with carbonaceous intercalations and an upper calcareous sandstone and mollusc banks; followed by up to 20 m of white limestones; then the immediate host, the 13 to 68 m thick, Middle Eocene Naqb Formation which is composed of a lower unit of non-fossiliferous dolomitic limestone, overlain by an upper unit of fossiliferous limestones with minor shale intercalations. The Naqb Formation limestones are intensely bioturbated dolomitised wackestones. The iron deposits are layered stratabound, lenticular bodies within the Naqb Formation comprising both lateritic muddy and sandy ironstones and glauconitic ironstone pockets and concretions developed as a result of subaerial exposure and lateritisation. These ironstones vary from 1 to 12 m in thickness, locally overlain by sands and gravels derived from the iron formation and older quartzites. Elsewhere the Naqb Formation is overlain by up to 75 m of limestones, and marls.
The mineralisation includes an oolitic type consisting essentially of goethite, a vesicular type containing hematite with pyrolusite and psilomelane, a hard, dark brown type consisting of goethite and hematite with some pyrolusite, and a low-grade limonitic type. The iron formation is characterised by abundant ferruginous sandstones that locally weather to form prominent iron crusts. These centimeter to decimeter-scale ferruginous horizons vary from unaltered sandstone with a pervasive ferruginous matrix to distinct ironstone beds with massive, nodular, vesicular and pisolitic textures. Ferruginous sandstone typically occurs at the top of sandstone beds (as iron-rich paleosol ferricrete horizons), or bracketing the base and top of beds, in the fining-upward cycles of deltaic plain deposits in the lower part of the formation and on a low-energy fluvial floodplain in the middle of the formation. Indurated ironstone beds occur mainly as the caps of coarsening-upward cycles of prograding shoreface sediments through much of the formation.
Mineralisation occurs in at least four localities at Bahariya Oasis, the Nasser, Gebel Ghorabi, El Harra, Al Heiz and El Gedida areas. Resource have been quoted (Abdulla, 1970) at 195 Mt @ 49 to 59% Fe, 2.6 to 9.1% SiO2, 0.35 to 0.84% S, 0.6 to 0.19% P, 2 to 4.5% Mn. Of this, approximately 135 Mt @ 55% Fe, 1.1% Mn, 0.9% S, 0.2% P, 4% SiO2 was outlined at El Gedida, to feed a steel smelting complex. Gebel Ghorabi contained 60 Mt @ 47% Fe, 3.1% Mn, 0.6% S, 0.1% P, 7% SiO2.
The Aswan iron deposits are located near Aswan on the Nile in northern Egypt and have been exploited to feed the local steel industry.
These deposits are hosted by the middle series of the Upper Cretaceous Nubian Sandstone which unconformably overlies a peneplained basement of igneous and metamorphic rocks. The Upper, Middle and Lower Nubian Sandstone vary in thickness from 70 to 120 m, and are essentially composed of conglomerates, sandstones, sandy shales, clays and quartzitic bands. The iron ore is a dark red, compact, oolitic hematite that occurs in two horizons separated by ferruginous sandstone. The lower band is 32 to 40 cm thick. The upper horizon is the most important, varying in thickness from 0.1 to 3.5 m with an average of 1 m. Less important deposits of the same type are also known, the main ones being in the south of Aswan at Kalabsha, Garf Hussein, Krusko and Abu Simbel.
Resource at Aswan have been quoted (Abdulla, 1970) at around 160 Mt @ 47% Fe, 14% SiO2.
The most recent source geological information used to prepare this decription was dated: 1998.
This description is a summary from published sources, the chief of which are listed below.
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