Conclusions

Hydrochemical characteristics of the water samples from the travertine-depositing vents and non-travetine-depositing vents in the Heinitang hot spring indicate that the precipitation of travertine deposits from the hot water is mainly affected by the concentration of CaCO30 and concentrations of CO2, PCO2 and the conditions of CO2-outgassing, and the effect of\(\text{\ \ }\mathrm{\gamma}\)Mg/\(\mathrm{\gamma}\)Ca and\(\mathrm{\gamma}\)Ca/\(\mathrm{\gamma}\)HCO3 on the precipitation of travertine is not obvious. The deposition of travertine is significantly affected by CaCO30. With the deposition of travertine, the concentration of CaCO30 in hot springs decrease. When the concentration of CaCO30 is higher than 0.018 mmol/L, the travertine consists of dolomite, calcite and aragonite, and the concentration of dolomite is higher than those of calcite and aragonite. When the CaCO30concentration is between 0.008 and 0.018 mmol/L, calcite is the main component of travertine. When the concentration of CaCO30 is lower than 0.008 mmol/L, the precipitation of travertine will hardly occur near the hot spring.