Control of Manganese Mineralization in Relation to the Tectonic History of the Red Sea Coastal Deposits

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Hassan Mohamed Ali, Aboul-Basher
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Geomorphologic, structural, stratigraphic and prospecting studies were carried out in the northern part of the Red Sea coastal plane (Lat. 20-25 N). These studies were based on the regional mapping, compilation work and detailed mapping of selected areas. The geomorphologic results have shown that palaeo-drainage is controlling the formation of the various havens known locally as marsas to a considerable extent. The presence of the crest of the Afro-Arabian swell in the Sudan, invaded by basic dykes is thought as one of the reliable evidences for correlation, where evidences of drifting are considered. No palaeozoec sediments were recorded in the area. The oldest rocks overlying the Basement are from the Nubian Sandstone Formation of Mesozoic-Tertiary age. The littoral sediments extending from Upper Cretaceous-Paleocene (Mukawar Formation) up to the Pleistocene-Recent times (Abu Shagara Formation) showed two peaks of recognizable subsidence and sedimentation at the Miocene and early Pleistocene times. Major fault a affecting the seaward gently dipping sediments were found with constant easterly throw. Folds were found to be only associated with major faults and thus considered to be related to faulting rather than compress ional stress. Basaltic flows of probably Plio-Pleistocene age represent the only volcanic activity, are closely related to faulting. Structural, stratigraphic and litho logical evidences from Sudan considered pertinent to the problem of the age and origin of the Red Sea were also discussed. Workable manganese deposits characterizing the northern region of the mapped area lave been studied in detail. They are differentiated into: a hydrothermal type associated with the Basement Complex and a sedimentary type restricted to littoral sediments. The latter is further differentiated into: (1) A type cementing glauconitic sandstone horizon recognizable in the northern region, and (2) A type represented by enriched deposits leached by descending solutions from the first. Mineralogical chemical, spectral and x-ray studies confirmed this classification which provides a good base for further prospecting, and exploration
: Control of Manganese Mineralization in Relation to the Tectonic History of the Red Sea Coastal Deposits