The Geology and Water Quality Study of The Mwakambiko Hill and Adjacent Areas,Mapatizya mining area,Kalomo District,Southern Province,Zambia
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The area north of Kariba Minerals Ltd is underlain by igneous rocks (pegmatite and dolerite) and metasedimentary rock units that have been ascribed to the Basement Complex Supergroup and Muva Supergroup. The rock units ascribed to the Basement Complex Supergroup include gneiss and marble whilst schist belongs to the Muva Supergroup. It is not clearly known whether amphibolite is of sedimentary or igneous origin and thus it has not been ascribed to any formation but it has been placed in Muva Supergroup. There is strong evidence that the marble is of magmatic origin and this ideology is based on the fact that marble contains xenoliths of assimilated country rock. The lithologies have been metamorphosed to upper almandine amphibolite facies and equally show evidence of retrogressive metamorphism though the grade has not been determined due to lack of indicator minerals in analyzed thin sections. Mapatizya Mining area generally occurs in a region that receives rainfall of below 700mm. Most of the rivers and streams that drain the area are intermittent. The poor water retains of the rock formations and rapid drying up of streams is attributed to; (1) high degree of weathering that has affected the lithologies, (2) faster flows of water in streams due to the steepness and rugged nature of the terrain and (3) high degree of fracturing and jointing exhibited by some of the rock formations. The primary sedimentary porosity of the rock formations have been obliterated by two episodes of metamorphism that affected the lithologies hence groundwater movement is limited to secondary porosity defined by fractures, joints, lithological contact boundaries, foliation and fault planes. Water availability is generally poor but field observation has shown that there is high possibility that the area might have good underground water reserves. Water for both domestic and industrial use is sourced from; boreholes, wells, natural springs and stream bed wells. The chemistry of the sampled water shows predominance of Calcium cation and Bicarbonate anion showing that there is a marked interaction of underground water with marble; this suggests that marble is possibly the aquifer. Lack of proper sewage system (use of pit latrines), bad garbage disposal habits and bad choice of feeding and drinking areas for live stocks have been found to be the major contributing factors to both surface and underground water contamination. This rapid contamination of underground water with fecal matter points to the fact that the aquifer is unconfined with its water table rising very close to the surface. Siltation of the only existing dam (Mbiko) is the visible evidence of the careless solid waste management by the existing mines which in the long run will also add elevated quantities of dissolved and suspended solids in both surface and underground water.
Student Report, 2008