Contributions to Mineralogy and Petrology

, Volume 146, Issue 4, pp 450–462 | Cite as

An experimental study of phase equilibria in the systems H2O–CO2–CaCl2 and H2O–CO2–NaCl at high pressures and temperatures (500–800 °C, 0.5–0.9 GPa): geological and geophysical applications

Original Paper

Abstract

Phase equilibria in the ternary systems H2O–CO2–NaCl and H2O–CO2–CaCl2 have been determined from the study of synthetic fluid inclusions in quartz at 500 and 800 °C, 0.5 and 0.9 GPa. The crystallographic control on rates of quartz overgrowth on synthetic quartz crystals was exploited to prevent trapping of fluid inclusions prior to attainment of run conditions. Two types of fluid inclusion were found with different density or CO2 homogenisation temperature (Th(CO2)): a CO2-rich phase with low Th(CO2), and a brine with relatively high Th(CO2). The density of CO2 was calibrated using inclusions in the binary system H2O–CO2. Mass balance calculations constrain tie lines and the miscibility gap between brines and CO2-rich fluids in the H2O–CO2–NaCl and H2O–CO2–CaCl2 systems at 500 and 800 °C, and 0.5 and 0.9 GPa. The miscibility gap in the CaCl2 system is larger than in the NaCl system, and solubilities of CO2 are smaller. CaCl2 demonstrates a larger salting-out effect than NaCl at the same P–T conditions. In ternary systems, homogeneous fluids are H2O-rich and of extremely low salinity, but at medium to high concentrations of salts and non-polar gases fluids are unlikely to be homogeneous. The two-phase state of crustal fluids should be common. For low fluid-rock ratios the cation compositions of crustal fluids are buffered by major crustal minerals: feldspars and micas in pelites and granitic rocks, calcite (dolomite) in carbonates, and pyroxenes and amphiboles in metabasites. Fluids in pelitic and granitic rocks are Na-K rich, while for carbonate and metabasic rocks fluids are Ca-Mg-Fe rich. On lithological boundaries between silicate and carbonate rocks, or between pelites and metabasites, diffusive cation exchange of the salt components of the fluid will cause the surfaces of immiscibility to intersect, leading to unmixing in the fluid phase. Dispersion of acoustic energy at critical conditions of the fluid may amplify seismic reflections that result from different fluid densities on lithological boundaries.

References

  1. Aranovich LYa, Newton RC (1996) H2O activity in concentrated NaCl solutions at high pressures and temperatures measured by the brucite-periclase equilibrium. Contrib Mineral Petrol 125:200–212CrossRefGoogle Scholar
  2. Aranovich LYa, Newton RC (1997) H2O activity in concentrated KCl and KCl–NaCl solutions at high temperatures and pressures measured by the brucite-periclase equilibrium. Contrib Mineral Petrol 127:261–271CrossRefGoogle Scholar
  3. Balashov VN (1995) Diffusion of electrolytes in hydrothermal systems: free solution and porous media. In: Shmulovich KI, Yardley BWD, Gonchar G (eds) Fluids in the crust. Chapman and Hall, London, pp 215–251Google Scholar
  4. Bodnar RJ, Sterner SM (1987) Synthetic fluid inclusions. In: Ulmer G, Barnes HL (eds) Hydrothermal experimental techniques. Wiley, New York, pp 423–457Google Scholar
  5. Coolen JJMMM (1982) Carbonic fluid inclusions in granulites from Tanzania—a comparison of geobarometric methods based on fluid density and mineral chemistry. Chem Geol 37:59–77Google Scholar
  6. Duan Z, Moller N, Wear JH (1995) Equation of state for NaCl–H2O–CO2 system: prediction of phase equilibria and volumetric properties. Geochim Cosmochim Acta 59:2869–2882Google Scholar
  7. Ford CE (1972) Furnace design, temperature distribution, calibration and seal design in internally heated pressure vessels. Progr Exp Petrol, Natural Environment Research Council (UK) Publ D2, pp 89–96Google Scholar
  8. Frantz JD, Popp RK, Hoering TC (1992) The compositional limits of fluid immiscibility in the system H2O–NaCl–CO2 as determined with the use of synthetic fluid inclusions in conjunction with mass spectrometry. Chem Geol 98:237–255CrossRefGoogle Scholar
  9. Frost DJ, Wood BJ (1997) Experimental measurements of the properties of H2O–CO2 mixtures at high pressures and temperatures. Geochim Cosmochim Acta 61:3301–3309CrossRefGoogle Scholar
  10. Gehrig M (1980) Phasengleichgewichte und PVT-Daten ternarer Misschungen aus Wasser, Kohlendioxid und Natriumchlorid bis 3 kbar und 550 °C. Doctoral Diss, Karlsruhe UniversityGoogle Scholar
  11. Gehrig M, Lentz H, Franck EU (1979) Thermodynamic properties of water-carbon dioxide-sodium chloride mixtures at high temperatures and pressures. In: Timmerhaus KD, Barber MS (eds) High-pressure science and technology. Plenum, New York, pp 534–542Google Scholar
  12. Herms P, Schenk V (1998) Fluid inclusions in high-pressure granulites of the Pan-African belt in Tanzania (Uluguru Mts): a record of prograde to retrograde fluid evolution. Contrib Mineral Petrol 130:199–212CrossRefGoogle Scholar
  13. Holloway JR, Burnham CW, Millhollen GL (1968) Generation of H2O–CO2 mixtures for use in hydrothermal experimentation. J Geophys Res 73:6598–6600Google Scholar
  14. Holness MB (1997) Surface chemical controls on pore-fluid connectivity in texturally equilibrated materials. In: Jamtveit B, Yardley BWD (eds) Fluid flow and transport in rocks. Chapman and Hall, London, pp 149–169Google Scholar
  15. Johnson EL (1991) Experimentally determined limits for H2O–CO2–NaCl immiscibility in granulites. Geology 19:925–928CrossRefGoogle Scholar
  16. Jones T, Nur A (1984) The nature of seismic reflections from deep crustal fault zones. J Geophys Res 89:3153–3171Google Scholar
  17. Joyce DB, Holloway JR (1993) An experimental determination of the thermodynamic properties of H2O–CO2–NaCl fluids at high pressures and temperatures. Geochim Cosmochim Acta 57:733–746CrossRefGoogle Scholar
  18. Kotel'nikov AR, Kotel'nikova ZA (1990) An experimental study of the phase state of the system H2O–CO2–NaCl using synthetic fluid inclusions in quartz. Geokhimia 4:526–537Google Scholar
  19. Kozlovsky EA (1984) Study of the deep structure of continental crust by drilling of the Kola superdeep borehole (in Russian). Nedra, Moscow, 490 ppGoogle Scholar
  20. Lide D (ed) (2002) CRC Handbook of chemistry and physics, 82nd edn. CRS Press, Boca RatonGoogle Scholar
  21. Markl G, Bucher K (1998) Composition of fluids in the lower crust inferred from metamorphic salt in lower crust. Nature 391:781–783CrossRefGoogle Scholar
  22. Oliver JE (1990) COCORP and fluids in the crust. In: Bredehoeft JD, Norton D (eds) The role of fluids in crustal processes. Natl Acad Press, Washington, DC, pp 128–139Google Scholar
  23. Popp RK, Frantz JD (1979) Mineral-solution equilibria, II. An experimental study of mineral solubilities and the thermodynamic properties of aqueous CaCl2, in the system CaO–SiO2–H2O–HCl. Geochim Cosmochim Acta 43:1777–1790CrossRefGoogle Scholar
  24. Potter RW, Clynne MC (1978) Solubility of highly soluble salts in aqueous media, Part I. NaCl, KCl, CaCl2, Na2SO4, and K2SO4 solubilities to 100 °C. J Res US Geol Surv 6:701–703Google Scholar
  25. Roedder E (1984) Fluid inclusions. Miner Soc Am, Rev Mineral 12Google Scholar
  26. Shapiro SA, Hubral P (1996) Elastic waves in finely layered sediments: the equivalent medium and generalized O'Doherty-Anstey formulas. Geophysics 61:1282–1300CrossRefGoogle Scholar
  27. Shmulovich KI, Graham CM (1996) Melting of albite and dehydration of brucite in H2O–NaCl fluids to 9 kbars and 700–900 °C: implications for partial melting and water activities during high pressure metamorphism. Contrib Mineral Petrol 124:370–382CrossRefGoogle Scholar
  28. Shmulovich KI, Graham CM (1999) An experimental study of phase equilibria in the system H2O–CO2–NaCl at 800 °C and 9 kbar. Contrib Mineral Petrol 136:2457–257CrossRefGoogle Scholar
  29. Shmulovich KI, Plyasunova NV (1993) High-temperature high-pressure phase equilibria in the ternary system H2O–CO2–salt (CaCl2, NaCl). Geokhimia 5:666–684Google Scholar
  30. Shmulovich KI, Tkachenko SI, Plyasunova NV (1995) Phase equilibria in fluid systems at high pressures and temperatures. In: Shmulovich KI, Yardley BWD, Gonchar G (eds) Fluids in the crust. Chapman and Hall, London, pp 193–214Google Scholar
  31. Skelton ADL, Bickle MJ, Graham CM (1997) Fluid-flux and reaction rate from advective-diffusive carbonation of mafic sill margins in the Dalradian, southwest Scottish Highlands. Earth Planet Sci Lett 146:527–539CrossRefGoogle Scholar
  32. Sloan ED (1990) Natural-gas-hydrate phase equilibria and kinetics—understanding the state-of-the-art. Rev I Fr Petrol 45:245–266Google Scholar
  33. Stevens G, Clemens JC (1993) Fluid-absent melting and the roles of fluids in the lithosphere: a slanted summary? Chem Geol 108:1–17Google Scholar
  34. Sterner SM, Bodnar RJ (1991) Synthetic fluid inclusions. X. Experimental determination of P-V-T-X properties in the CO2–H2O system to 6 kbar and 700 °C. Am J Sci 291:1–54Google Scholar
  35. Takenouchi S, Kennedy GC (1965) The solubility of carbon dioxide in NaCl solutions at high temperatures and pressures. Am J Sci 263:445–454Google Scholar
  36. Touret J (1985) Fluid regime in southern Norway: a record of fluid inclusions. In: Tobi AC, Touret JLR (eds) The deep Proterozoic crust in the north Atlantic provinces. NATO ASI Series C158, Reidel, Dordrecht, pp 517–549Google Scholar
  37. Touret JLR (1995) Brines in granulites: the other fluid. Bol Soc Esp Mineral 18(1):250–251Google Scholar
  38. Vanko DA, Griffith JD, Erickson CL (1992) Calcium-rich brines and other hydrothermal fluids in fluid inclusions from plutonic rocks, Oceanographer Transform, Mid-Atlantic Ridge. Geochim Cosmochim Acta 56:35–47Google Scholar
  39. Walther JV, Orville PM (1982) Volatile production and transport in regional metamorphism. Contrib Mineral Petrol 79:252–257Google Scholar
  40. Watson EB, Brenan JM (1987) Fluids in the lithosphere, I. Experimentally-determined wetting characteristics of CO2–H2O fluids and their implications for fluid transport, host-rock physical properties, and fluid inclusion formation. Earth Planet Sci Lett 85:497–515Google Scholar
  41. White DE (1965) Saline waters in sedimentary rocks. Am Assoc Petrol Geol Mem 4:342–366Google Scholar
  42. Xie Z, Walther JV (1993) Quartz solubilities in NaCl solutions with and without wollastonite at elevated temperatures and pressures. Geochim Cosmochim Acta 57:1947–1955Google Scholar
  43. Yardley BWD (1996) The evolution of fluids through the metamorphic cycle. In: Jamtveit B, Yardley, BWD (eds) Fluid flow and transport in permeable rocks. Chapman and Hall, London, pp 99–119Google Scholar
  44. Yardley BWD, Graham JT (2002) The origins of salinity in metamorphic fluids. Geofluids, in 2:249–256Google Scholar
  45. Yardley BWD, Valley JW (1997) The petrological case for a dry lower crust. J Geophys Res 102:12173–12185Google Scholar
  46. Zatsepin SV, Crampin S (1997) Modelling the compliance of crustal rocks: I – response of shear-wave splitting to differential stress. Geophys J Int 129:477–494Google Scholar
  47. Zhang Y-G, Frantz JD (1989) Experimental determination of the compositional limits of immiscibility in the system CaCl2–H2O–CO2 at high temperatures and pressures using synthetic fluid inclusions. Chem Geol 74:289–308CrossRefGoogle Scholar
  48. Zotov AV, Kudrin AV, Levin KA, Shikina ND, Var'yash LN (1995) Experimental studies of the solubility and complexing of selected ore elements (Au, Ag, Cu, Mo,As, Sb, Hg) in aqueous solutions. In: Shmulovich KI, Yardley BWD, Gonchar G (eds) Fluids in the crust. Chapman and Hall, London, pp 95–138Google Scholar

Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  1. 1.School of Geo SciencesUniversity of EdinburghEdinburgh UK
  2. 2.Institute of Experimental MineralogyRussian Academy of SciencesMoscowRussia

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