Abstract:
Most of the radioactive occurrences located in the Kamlial Formation of Salt Range area are insignificant for uranium exploration due to low radioactivity and spotty nature. The radioactive anomalies of Kallar Kahar area, in the vicinity of Chhumbi village (Toposheet No. 43 D/9) are important because they show high values of radioactivity, uranium content and -continuity along a strike length of more than one kilometer. These radioactive anomalies and uranium occurrences are associated with the middle and upper Kamlial Formation of Chhumbi synclinal structure. The anomalous radioactivity of the range 400 - 7000 Cps. is associated with the intraformational conglomeratic channels, gray sandstone and a mixed zone of channel and sandstone. The sandstone also contains visible uranium mineralization identified as SALEITE, a secondary uranium mineral. The anomalous values of radioactivity and uranium content (100 - 1650 ppm) associated with the host sandstone indicate possibility for the formation of a remobilize type of uranium ore body in the subsurface. For the evaluation of this uranium prospect, studies regarding uranium source, its leaching and mobilization were conducted. For this purpose chemical and mineralogical analysis of the surface rock samples collected from the host sandstone were carried out. The mineralogical analyses indicate that anomalous sandstone is feldspathic litharenite in nature. It contains a lot of volcanogenic material as uranium source. For the observation of uranium leaching from the host sandstone, disequilibrium studies and comparison between U3O8, and eU3O8 were established. The disequilibrium studies indicated strong leaching of uranium from the host sandstone because all samples fall in the field of negative disequilibrium. Similarly comparison between U3O8, and eU3O8 shows depletion of uranium as eU3O8 content is higher than U3O8 in all samples. For observing the uranium mobilization, comparison between U+4 and U+6 was conducted. The values of U+6 are very low (at ppb level) as compared to U+4. This indicates that the uranium content, which was oxidized from U+4 to U+6 has been mobilized from the surface of the host sandstone leaving behind the oxidized uranium in negligible amounts. The hydro-geochemical survey of the Kallar Kahar area also shows anomalous value of uranium content (36-47 ppb) in the water samples collected from the uranium occurrences with the background value of 6 ppb. This fact also points towards the uranium mobilization. On the basis of surface investigation, subsurface studies through core drilling has just been initiated in the area. A few boreholes, so for drilled has indicated radiometric zones in the subsurface below the ground water table with anomalous uranium content.
Page(s):
313-324
DOI:
DOI not available
Published:
Journal: Proceedings of 5th Pakistan Geological Congress , Volume: 0, Issue: 0, Year: 2007