Abstract:
Metasilicate mineral water is widely distributed throughout granite area in South China. This study investigated the distribution characteristics and formation mechanism of metasilicate mineral water in granite area, and used granite-type metasilicate mineral water in Zhuhai as a representative case. The spatial distribution and hydrogeochemical properties were characterized through integrated geostatistical and hydrogeochemical analyses. Besides, the formation mechanism and controlling factors of metasilicate mineral water were identified. The results show that the metasilicate mineral water is dominated by HCO
3-Ca·Mg type and mixed HCO
3-Ca·Na type, while groundwater with lower metasilicate is dominated by mixed Cl-Ca·Mg type. The concentration of metasilicate in groundwater ranges from 3.54 to 121.68 mg/L, with a mean value of 29.02 mg/L. Eighty specimens were qualified as metasilicate mineral water, accounting for 37.91%. The metasilicate mineral water was mainly distributed in the piedmont zones of Huangyang Mountain and Fenghuang Mountain. The granite in the study area possessed a characteristic of high-silicon geochemical signature, and the geological formation was the material basis for metasilicate mineral water. The silicon migrated into the groundwater system with the weathering of granite, leading to metasilicate groundwater. The weathering and hydrolysis of silicate minerals play a dominant controlling role in the chemical characteristics of metasilicate mineral water, and the metasilicate in groundwater mainly derives from the incongruent dissolution of anorthite, albite, potassium feldspar. These findings could provide scientific framework for the investigation, evaluation and sustainable utilization of metasilicate mineral water resources.