Hydrochemical and isotopic evidence of origin of thermal karst water at Taiyuan, northern China

Abstract

Thermal karst groundwaters with temperatures ranging from 32.8 to 62.5 °C were found at Taiyuan (太原) City, the capital of Shanxi (山西) Province. To identify the origin of the thermal groundwater, the following tracers were used in this study: δD, δ ¹⁸O, ⁴He, ³He/⁴He, and major chemical constituents in water. Hydrochemical and isotopic data indicate that the thermal groundwaters in the basin area are a mixture of thermal waters from the West Mountain and those from the East Mountain. Furthermore, the ⁴He and ⁴He_exc concentrations of the thermal groundwater samples are usually lower than those of the cold groundwater samples, and there is an evidently negative correlation between the temperature and the ⁴He concentration in thermal groundwaters from the West Mountain and the basin, which means that with the increase in temperature, the He concentration increases in the vapor phase and decreases in the aqueous phase. In the plot of ³He/⁴He vs. ⁴He/²⁰Ne of all water samples: air, crust, and mantle, all thermal groundwater samples are distributed near the line between the point of air and that of crust, suggesting that atmospheric and crustal helium is the main source for that in thermal groundwaters. In other words, there are no mantle-derived fluids mixed in the thermal groundwaters.

Keywords

thermal groundwater / origin / hydrochemistry / isotope / ³He/⁴He / Taiyuan

References

[1] Andrews J. N.. The Isotopic Composition of Radiogenic Helium and Its Use to Study Groundwater Movement in Confined Aquifers. Chemical Geology, 1985, 49(1–3): 339-351.

[2] Ballentine C. J., Burnard P.. Production, Release and Transport of Noble Gases in the Continental Crust. Reviews in Mineralogy and Geochemistry, 2002, 47: 481-538.

[3] Bottomley D. J., Ross J. D., Clarke W. B.. Helium and Neon Isotope Geochemistry of Some Ground Waters from the Canadian Precambrian Shield. Geochimica et Cosmochimica Acta, 1984, 48(10): 1973-1985.

[4] Castro M. C., Stute M., Schlosser P.. Comparison of ⁴He Ages and ¹⁴C Ages in Simple Aquifer Systems: Implications for Groundwater Flow and Chronologies. Applied Geochemistry, 2000, 15(8): 1137-1167.

[5] Chen M., Wang J., Deng X.. The Map of Geothermal System Types in China and Its Brief Explanation. Scientia Geologica Sinica, 1996, 31(2): 114-121.

[6] Davis S., DeWiest R. J.. Hydrogeology, 1966, New York: Wiley 463

[7] Heaton T. H. E., Vogel J. C.. Excess Air in Groundwater. Journal of Hydrology, 1981, 50(1–4): 201-216.

[8] Hou Y. S.. Research on the Geothermal Resources of Border Mount Fracture Zone in Taiyuan Region. Coal Geology of China, 2002, 14(4): 38-42.

[9] Justin T. K., David R. H.. Helium Isotope Studies in the Mojave Desert, California: Implications for Groundwater Chronology and Regional Seismicity. Chemical Geology, 2003, 202(1–2): 95-113.

[10] Kennedy B. M., van Soest M. C.. A Helium Isotope Perspective on the Dixie Valley, Nevada, Hydrothermal System. Geothermics, 2006, 35(1): 26-43.

[11] Kraynov S. R., Ryzhenko B. N., Shvets V. M., . Geochemistry of Grund Water: Theoretical, Applied and Environmental Aspects, 2004, Moscow: Nauka 374-376.

[12] Lupton J. E.. Terrestrial Inert Gases: Isotope Tracer Studies and Clues to Primordial Components in the Mantle. Annual Reviews in Earth and Planetary Sciences, 1983, 11: 371-414.

[13] Sano Y., Wakita H.. Precise Measurement of Helium Isotopes in Terrestrial Gases. Bulletin of the Chemical Society of Japan, 1988, 61: 1153-1157.

[14] Stute M., Sonntag C. D., Schlosser P., . Helium in Deep Circulating Groundwater in the Great Hungarian Plain: Flow Dynamics and Crustal and Mantle Helium Fluxes. Geochimica et Cosmochimica Acta, 1992, 56(5): 2051-2067.

[15] Tetsuya Y., Shun I. N., Hiroshi W.. Helium and Carbon Isotopic Compositions of Hot Spring Gases in the Tibetan Plateau. Journal of Volcanology and Geothermal Research, 1999, 88(1–2): 99-107.

[16] Torgersen T., Drenjard S., Stute M., . Mantle Helium in Ground Waters of the Eastern North America: Time and Space Constraints on Sources. Geology, 1995, 23: 675-678.

[17] Torgersen T., Ivey G. N.. Helium Accumulation in Groundwater II: A Model for the Accumulation of the Crustal ⁴He Degassing Flux. Geochimica et Cosmochimica Acta, 1985, 49(11): 2445-2452.

[18] Yan S. L., Wang R. F., Gan Y. Q.. Wang Y. X.. Geochemistry of Thermal Groundwaters at Shentanggou, Taiyuan, China. Proceeding of the International Symposium on Water Resources and the Urban Environment, 2003, Beijing: China Environmental Science Press 137-141.

[19] Zuber A., Weise S. M., Motyka J.. Age and Flow Pattern of Groundwater in a Jurassic Limestone Aquifer and Related Tertiary Sands Derived from Combined Isotope, Noble Gas and Chemical Data. Journal of Hydrology, 2004, 286(1–4): 87-112.