Abstract
The geochemistry of regional groundwater has been utilized worldwide to discover subsurface mineral deposits, though it has not yet been practiced in Sri Lanka. The present study focuses on utilizing geochemistry of groundwater in the Udawalawe area of south-central Sri Lanka where two serpentinite bodies exist within the high-grade crystalline basement. This area is in the proximity of the litho-tectonic boundary between two metamorphic complexes. Thus, the scope of the study is to uncover geological and geochemical anomalies of potential mineralization. Mode of occurrences and petrography of exposed serpentinite bodies and physico-chemical properties of groundwater were investigated to establish a relationship between regional groundwater geochemistry and geological anomalies. The pH and electrical conductivity of groundwater were measured in-situ and concentrations of Al, Ba, Be, Cs, Cu, Fe, Li, Mn, Pb, Rb, Sr and Zn were analysed using atomic absorption and emission spectroscopy. The present study reveals that concentrations of these elements are significantly higher close to serpentinite bodies with Cu and Zn having the highest concentrations. Elevated concentrations of Al, Ba, Be, Fe, Li, Pb, Rb and Sr were also noted. Relatively higher concentrations of Be, Cu, Li, Mn, Pb, Rb and Zn in groundwater in the area between the two exposed serpentinite bodies indicate the possible occurrence of a subsurface mineral deposit in the area. These results indicate the importance and feasibility of the application of regional groundwater geochemistry as a tool for uncovering subsurface mineral deposits. Detailed observations of groundwater flow patterns, facies changes, and associated element mobility could effectively help in accurate demarcation of the lateral extents of mineral deposits.
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