The studied Mn-Fe ore deposits always tend to occupy a particular stratigraphic horizon, representing the lower member of Um Bogma Formation which belongs to the Lower Carboniferous. Mn-Fe ore deposits at Um Bogma area do not show the uniform characteristics of beds either in thickness or in lateral continuity. In some occurrences, the ore bodies are present as sills, veins, fracture filling and also found on the normal fault plane. All of these field criteria reveal hydrothermal origin of Mn-Fe ore deposits at Um Bogma area. Mineralogically, kaolinite mineral is recorded in the studied Mn-Fe ore deposits in the four localities, also Hausmanite and manganite detected in some localities (Allouga and Um Bogma) for the first time indicating hydrothermal origin. The suggestion of hydrothermal origin is further supported by the enrichment of Ba, Zn, Pb, As, U, V, Cu, and Sr, and depletion in Na, Mg, K, Ca and Ni in the studied Mn-Fe ore deposits. The studied Mn-Fe ore deposits show lowΣ REEs contents, enrichment in LREEs relative to HREEs and strong negative Ce anomalies. Also, all of these geochemical data confirm the hydrothermal origin. In many localities manganese-iron ore bodies have spots reflecting high radioactivity reaches up to 527 ppm of eU. The average of eU/eTh ratio for the studied samples of Mn-Fe ore deposits of the four localities ranges between 4.0 up to 5.6 provide hydrothermal origin or may be later hydrothermal enrichment of the manganese ore. Sayrite, thorite and uranothorite represents the radioactive minerals detected in the studied Mn-Fe ore. Pinakiolite, rinmanite, turquoise, aheylite and gold also detected as accessory minerals.
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