**6. Conclusion**

The Pidong Crater Lake water is majorly meteoric origin probably coming from percolating meteoric waters of relatively young age (230 ± 30 years before present). The chemical element composition of the Lake is dominantly of Mg-HCO3 water type, influenced mainly by the interaction between meteoric water and basaltic rocks with surrounding granitic host rock from relatively deeper aquifers. In addition, the chemical composition of the lake water is further influenced by minor CO2 degassing, attributable to minor intermittent fumaroles activities possibly from deep mantle source.
