Geochemistry of Groundwater Over Sukinda Ultrabasic - Basic Rocks, Jajpur District, Orissa

The geochemistry of groundwater over Sukinda ultrabasic - basic rocks, Orissa, covering an areat extent of about 50 km², has been investigated to understand the hydrogeology of the area. The dominant geochemical processes were interpreted from geochemical data and mass balance calculations. The entire study area contains two broad lithounits comprising ultrabasic rock at the centre and metabasics at eastern and western flanks, with a general groundwater flow pattern from east to west. The groundwater in the area is fresh, meteoric in origin with high Na, Kover metabasics as well as the northern part of the ultrabasic rock, and high Mg, HCO₃^- and TDS over the remaining ultrabasic rock. Mineral solubility study of Mg^- phases present in the system shows that the present day geochemical conditions are not suitable for Mg²⁺ precipitation and most likely, serpentine is the dominant Mg²⁺ contributer in the system. Mass balance calculations based on mixing ratio along the E-W flow path show that K and to some extent Na behave conservatively in the evolution of groundwater. The conservative mixing model presented here evaluates the formation of secondary mineral phases along the flow path.