Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Experimental observation of deep crust fluid-NaCl aqueous solution at elevated temperatures and pressures and its significance

  • 15 Accesses

  • 8 Citations

Abstract

In order to reveal the nature of deep crust fluids, the phase relations of NaC1-saturated solution at high temperatures and pressures in a hydrothermal diamond anvil cell (HDAC) are investigated. Salinity of the solutions observed is about 35%–50%. The temperatures for the observation range from 25 to 850°C and the pressures from 1 atm to about 1 GPa. A supercritical single phase, liquid phase (L), vapor phase (V), solid phase (H), L+H, H + V + L and the near-critical phases L + V can be observed. A two-phase (L + V) immiscibility field for the NaCl solution has been discovered to lie in a wide range of temperatures and pressures: from 250(±3) to 721°C. Within this field there are two parts, where the upper high temperature part of the two-phase regions is very unstable in character.

It is possible to observe a “critical phenomenon”. In some of our experiments an “explosion” almost constantly occurred at the interface between the liquid and vapor phases, making the interface obscure, and a continuous transition between the two phases could be found. By a visual microscope it was found that in the two-phase immiscible field near to the critical state the vapor phase and liquid phase compose a crystal structure geometry. It is a special solution structure that was found under a microscope. This discovery is important for us to understand the reason of increasing electronic conductivity of NaCl aqueous solution with respect to temperatures and pressures. And also, it will be easy to interpret the variation of electronic conductivity in the earth crust.

This is a preview of subscription content, log in to check access.

References

  1. 1

    Anderko, A., Pitzer, K., Equation-of-state of phase equilibria and volumetric properties of the system NaCI-H2O above 573°K.Geochim. Cosmochim. Acta, 1993, 57: 1657.

  2. 2

    Bischoff, J. L., Densities of liquids and vapors in boiling NaCI-H2O solutions: a PVXT summary frum 300 to 5009:°C,A. J. S., 1991, 291: W.

  3. 3

    Bischoff, J. L., Pitzer, K. S., Phase relation adiabats in boiling seafloor geochemical systems,Earth P.S.L., 1985, 75: 327.

  4. 4

    Bischoff, J. L., Pitzer, K. S., Liquid-vapor relations for the system SaCl-H2O: summary of theP-T-X surface frum 300 to 5009:.A. J. S., 1989, 289: 217.

  5. 5

    Bischoff, J. L., Rosenbaur, R. J., Salinity of variations in submarine hydrothermal system by double-diffusive convection,J. Geol., 1989, 97: 613.

  6. 6

    Bodnar, R. J., Synthetic fluid inclusions: XI. The system NaC1-H2O experimental determination of the halite liquidus and isochres for a 40% NaCl solution,Geochim. Cosmochim. Acta, 1994, 58(3): 1053.

  7. 7

    Chou, I-Ming, Phase relations in the system NaCI-KCI-H2O: III. Solubilities of halite in vapor-saturated liquids above system NaCl-H2O to 100°C, and 1500 bars,Geochim. Cosmochim, Acta. 1987, 51: 1965.

  8. 8

    Gunter, W. D., I-Ming Chw, Girsperger, S., Phase relations in the systems NaCI-H2O: II. Differential thermal analysis of the halite liquids in the NaCl-H2O binary system above 450°C,Geochim. Cosmochim. Acta, 1983, 47: 863.

  9. 9

    Johnson, W. J., Norton, D., Critical phenomena in the thermal systems: state, thermodynamic, electrostatic, and tranport properties of H2O in the critical region,Ame. Jour. Sci., 1991, 291: 541.

  10. 10

    Knight, G. C., Bodnar, R. J., Synthetic fluid inclusions: IX. Critical PVTX properties of NaCl solutions,Geochim. et Cosmochim. Acta, 1989, 53: 3.

  11. 11

    Marshall, W. L., Critical curves of aqueous electrolytes related to ionization behaviors: new temperatures for sodium chroride solutions,J. Chem. Soc. Faraday., 1990, 86(10): 1807.

  12. 12

    Bassett, W. A., Shen, A. H., Buchnum, M. J.et al., New diamond anvil cell for hydrothermal studies to 2.5 GPa and from 190 to 1200°C,Rev. Sci. Instrum., 1993, 64: 2304.

  13. 13

    Bassett, W. A., Dhen, A. H.. Bucknum, M.et al., Hydrothermal studies in a new diamond anvil cell up to 10 GPa and from -190 to 1200°C,Pageoph., 1993. 141(2-4): 487.

  14. 14

    Chou I-Ming. Sterner, S. M., Pitzer, K. S., Phase relations in the system NaCl-KCl-H2O: M. Differential thermal analysis of the sylvite liquidw in KCl-H2O binary, the liquidus in the NaCl-KCI-H2O ternary, and the sodidus in the NaCl-H2O binary to 2 kilobars pressure, and a summary of experimental data for thermodynamicPTX analysis of solid-liquid equilibria at elevatedP-T conditions,Geochim. Carmochim. Acta, 1992, 56: 2281.

  15. 15

    Shen, A. H., Bassen, W. A., Chou, I. M., Hydrothermal studies in a diamond anvil cell: I. Pressure determination using the equation of state of H2O,High Pressure Research: Application to Earth and Planary Sciences”, Tokyo, Japan/AGU Washington, D.C.: Terra Sci. Pub. Co., 1992, 61–68.

  16. 16

    Shen, A. H., Bassett, W., Chou I-Ming, The α-β quartz transition observed at simultaneou high temperatures and high pressures in a diamond-anvil cell by laser interermetry,Amer. Miner., 1993, 78: 694.

  17. 17

    Koster Van Groose, Differential thermal analysis of the liquidus relations in the system NaCl-H2O to 6 kbar,Geochim. Cosmochim. Acta, 1991, 55: 2811.

  18. 18

    Committee of Geoscience Transect, State Department of Seismology,Geoscience Transect From Eastern Wuzhumqin Inner Mongolia ta Donggou Liaoning (in Chinese), Beijing: Seismology h. 1992.

Download references

Author information

Correspondence to Ronghua Zhang.

About this article

Cite this article

Zhang, R., Hu, S. Experimental observation of deep crust fluid-NaCl aqueous solution at elevated temperatures and pressures and its significance. Chin. Sci. Bull. 44, 654–660 (1999). https://doi.org/10.1007/BF03182730

Download citation

Keywords

  • two phsse immiscibility
  • critical phenomenon
  • solution structure