Haruna, and three co-authors, reported in 2017 on the occurrence of uranium-bearing rocks in the area and discuss the source, mechanism of migration and structures or rock-type hosting the uranium mineralization. This was achieved by an integration of radiation point count, petrographic studies and structural analysis. This is necessary because the Gubrunde uranium occurrence is one of the several known leads to possible extensive mineralization in North East Nigeria that have been least studied even in the midst of the increasing quest for local clean and cheap energy becasue uranium could be exported to world markets if mined.
The area has favorable geological environment and conditions for uranium mineralization. Field relationships show that structurally and tectonically controlled Cretaceous continental sandstones are underlain by acidic granites of the Precambrian basement complex. These are in some places, intruded by much younger volcanic which forms traps for uraniferous solution being transported by hydrothermal fluid in structural conduits. Structural analysis of structures in the area showed a NNE-SSW deformational trend. Samples of rocks from the entire area shows dark to brown opaque minerals suspected to be uranium (uraninite or coffinite). Radiation point count confirms the occurrence of radiation ranging from 7.5×104 µCi - 6.40×105 µCi concentration levels. There is structural and geochemical control to mineralization in the area. Radiation levels at some points were noted to be above human-tolerable levels.
The authors concluded that the structural hosts of uranium in the area are the fault and fractures. The uranium ores found in these structures are primary in nature given that the faults and fractures are deep seated and are connected to the volcanic root that emplaced the rock. The primary source of uranium in the area is magmatic. Magma containing elemental uranium as REE starts partial crystallization and the uranium element is further concentrated in the remaining magma melt. The melt finally crystallizes to form rocks rich in uranium ore (primary deposits).
Another host of uranium is the Bima sandstones and are secondary in nature. These are the most widespread type of deposit in the area. Secondary uranium is formed by the re-mobilization of uranium in rocks by reducing groundwater through structured conduits into sediments. The sandstones are formed as weathering product of Precambrian basement rocks as a result of severe change in environmental factors. The sandstones are deposited on the basement either in situ or transported. The Jurassic tectonism that resulted in further granitization and deformation also fractured and faulted the pre-existing basement cum sediment and a passage way for mineralizing fluid was created. The uranium contained in remaining magmatic melt mixed with reducing groundwater (hydrothermal fluid) thus passed through the Jurassic-aged conduits to mineralize the sandstones. This explains why uranium mineralization is highest at sandstone ridges and appear to decrease away from fault zones in sandstones. This also explains the difference in concentration of uranium at Kikongo, Northern Cameroon using this analogy. The flow of residual fluid into the sandstones also resulted in the silicification of sandstone. Silicification necessarily provided the much needed reducing environment for uranium mineralization.
The sandstone-type deposit of uranium is thought to contain the coffinite ore because of the widespread alteration. The two types of uranium ore proposed for the area corresponds to the sources explained above. The primary deposits is inferred to contain the uraninite ore type because of its primary and unaltered nature in granitic and other equivalent host rocks and the secondary deposits is inferred to contain the coffinite because of its altered nature in the sandstone host. There is both structural and geochemical control to the mineralization just as has been reported by other workers.
The health implication of the radiation from uranium could be adverse. Therefore an expert should look into the health effect of the radioactive deposits on the people is highly advised and prompt action taken thereafter. [Of course these deposits (and the radioactivity) have been present for millions (if not billions) of years and any damage has been done and is ongoing ....??. Mining uranium as a remedial action? How about investigating local groundwater used as a water supply for drinking, etc.? Need to check streams, dug wells, and drilled wells for surface and groundwater with high uranium, radium, radon, and other metals?]
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