Abstract
The chemistry of aqueous fluids controls the transport and exchange—the cycles—of metals1,2,3,4,5 and volatile elements3,6,7 on Earth. Subduction zones, where oceanic plates sink into the Earth’s interior, are the most important geodynamic setting for this fluid-mediated chemical exchange2,6,7,8,9,10. Characterizing the ionic speciation and pH of fluids equilibrated with rocks at subduction zone conditions has long been a major challenge in Earth science11,12. Here we report thermodynamic predictions of fluid–rock equilibria that tie together models of the thermal structure, mineralogy and fluid speciation of subduction zones. We find that the pH of fluids in subducted crustal lithologies is confined to a mildly alkaline range, modulated by rock volatile and chlorine contents. Cold subduction typical of the Phanerozoic eon13 favours the preservation of oxidized carbon in subducting slabs. In contrast, the pH of mantle wedge fluids is very sensitive to minor variations in rock composition. These variations may be caused by intramantle differentiation, or by infiltration of fluids enriched in alkali components extracted from the subducted crust. The sensitivity of pH to soluble elements in low abundance in the host rocks, such as carbon, alkali metals and halogens, illustrates a feedback between the chemistry of the Earth’s atmosphere–ocean system14,15 and the speciation of subduction zone fluids via the composition of the seawater-altered oceanic lithosphere. Our findings provide a perspective on the controlling reactions that have coupled metal and volatile cycles in subduction zones for more than 3 billion years77.
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References
Eugster, H. P. Minerals in hot water. Am. Mineral. 71, 655–673 (1986)
Hedenquist, J. W. & Lowenstern, J. B. The role of magmas in the formation of hydrothermal ore deposits. Nature 370, 519–527 (1994)
Pokrovski, G. S. & Dubrovinsky, L. S. The S3− ion is stable in geological fluids at elevated temperatures and pressures. Science 331, 1052–1054 (2011)
Phillips, G. N. & Evans, K. A. Role of CO2 in the formation of gold deposits. Nature 429, 860–863 (2004)
Dolejs, D. & Wagner, T. Thermodynamic modeling of non-ideal mineral-fluid equilibria in the system Si-Al-Fe-Mg-Ca-Na-K-H-O-Cl at elevated temperatures and pressures: implications for hydrothermal mass transfer in granitic rocks. Geochim. Cosmochim. Acta 72, 526–553 (2008)
Evans, K. A. The redox budget of subduction zones. Earth Sci. Rev. 113, 11–32 (2012)
Hayes, J. M. & Waldbauer, J. R. The carbon cycle and associated redox processes through time. Phil. Trans. R. Soc. Lond. B 361, 931–950 (2006)
Eiler, J. M., McInnes, B., Valley, J. W., Graham, C. M. & Stolper, E. M. Oxygen isotope evidence for slab-derived fluids in the sub-arc mantle. Nature 393, 777–781 (1998)
Stolper, E. & Newman, S. The role of water in the petrogenesis of Mariana trough magmas. Earth Planet. Sci. Lett. 121, 293–325 (1994)
Galvez, M. E. et al. Graphite formation by carbonate reduction during subduction. Nat. Geosci. 6, 473–477 (2013)
Ni, H., Chen, Q. & Keppler, H. Electrical conductivity measurements of aqueous fluids under pressure with a hydrothermal diamond anvil cell. Rev. Sci. Instrum. 85, 115107 (2014)
Ding, K. & Seyfried, W. E. Direct pH measurement of NaCl-bearing fluid with an in situ sensor at 400 C and 40 megapascals. Science 272, 1634–1636 (1996)
Brown, M. Duality of thermal regimes is the distinctive characteristic of plate tectonics since the Neoarchean. Geology 34, 961–964 (2006)
Anbar, A. D. Elements and evolution Science 322, 1481–1483 (2008)
Staudigel, H. & Hart, S. R. Alteration of basaltic glass: Mechanisms and significance for the oceanic crust-seawater budget. Geochim. Cosmochim. Acta. 47, 337–350 (1983)
Poli, S. Carbon mobilized at shallow depths in subduction zones by carbonatitic liquids. Nat. Geosci. 8, 633–636 (2015)
Hirth, G. & Kohlstedt, D. L. Water in the oceanic upper mantle: implications for rheology, melt extraction and the evolution of the lithosphere. Earth Planet. Sci. Lett. 144, 93–108 (1996)
Fischer, W. W. et al. SQUID–SIMS is a useful approach to uncover primary signals in the Archean sulfur cycle. Proc. Natl Acad. Sci. USA 111, 5468–5473 (2014)
Pan, D., Spanu, L., Harrison, B., Sverjensky, D. A. & Galli, G. Dielectric properties of water under extreme conditions and transport of carbonates in the deep Earth. Proc. Natl Acad. Sci. USA 110, 6646–6650 (2013)
Sverjensky, D. A., Harrison, B. & Azzolini, D. Water in the deep Earth: the dielectric constant and the solubilities of quartz and corundum to 60kb and 1200° C. Geochim. Cosmochim. Acta 129, 125–145 (2014)
Galvez, M. E., Manning, C. E., Connolly, J. A. & Rumble, D. The solubility of rocks in metamorphic fluids: a model for rock-dominated conditions to upper mantle pressure and temperature. Earth Planet. Sci. Lett. 430, 486–498 (2015)
Mountain, R. D. & Harvey, A. H. Molecular dynamics evaluation of dielectric constant mixing rules for H2O–CO2 at geologic conditions. J. Solution Chem. 44, 2179–2193 (2015)
Wood, B. J. & Walther, J. V. Rates of hydrothermal reactions. Science 222, 413–415 (1983)
Manning, C. E., Antignano, A. & Lin, H. A. Premelting polymerization of crustal and mantle fluids, as indicated by the solubility of albite + paragonite + quartz in H2O at 1GPa and 350–620° C. Earth Planet. Sci. Lett. 292, 325–336 (2010)
Aranovich, L. Y. & Newton, R. C. Experimental determination of CO2-H2O activity-composition relations at 600–1000 degrees C and 6–14 kbar by reversed decarbonation and dehydration reactions. Am. Mineral. 84, 1319–1332 (1999)
Liou, J., Zhang, R. & Ernst, W. Occurrences of hydrous and carbonate phases in ultrahigh-pressure rocks from east-central China: implications for the role of volatiles deep in cold subduction zones. Isl. Arc 4, 362–375 (1995)
Rohrbach, A. & Schmidt, M. W. Redox freezing and melting in the Earth’s deep mantle resulting from carbon-iron redox coupling. Nature 472, 209–212 (2011)
Li, H. & Hermann, J. Apatite as an indicator of fluid salinity: an experimental study of chlorine and fluorine partitioning in subducted sediments. Geochim. Cosmochim. Acta 166, 267–297 (2015)
Parkinson, I. J. & Pearce, J. A. Peridotites from the Izu–Bonin–Mariana forearc (ODP Leg 125): evidence for mantle melting and melt–mantle interaction in a supra-subduction zone setting. J. Petrol. 39, 1577–1618 (1998)
Mikhail, S. & Sverjensky, D. A. Nitrogen speciation in upper mantle fluids and the origin of Earth’s nitrogen-rich atmosphere. Nat. Geosci. 7, 816–819 (2014)
Ryabchikov, I., Schreyer, W. & Abraham, K. Compositions of aqueous fluids in equilibrium with pyroxenes and olivines at mantle pressures and temperatures. Contrib. Mineral. Petrol. 79, 80–84 (1982)
Wilke, M. et al. Zircon solubility and zirconium complexation in H2O+Na2O+SiO2±Al2O3 fluids at high pressure and temperature. Earth Planet. Sci. Lett. 349-350, 15–25 (2012)
Salvi, S., Pokrovski, G. S. & Schott, J. Experimental investigation of aluminum-silica aqueous complexing at 300 C. Chem. Geol. 151, 51–67 (1998)
Connolly, J. A. D. Multivariable phase diagrams; an algorithm based on generalized thermodynamics. Am. J. Sci. 290, 666–718 (1990)
Holland, T. & Powell, R. An internally consistent thermodynamic data set for phases of petrological interest. J. Metamorph. Geol. 16, 309–343 (1998)
Caddick, M. J. & Thompson, A. B. Quantifying the tectono-metamorphic evolution of pelitic rocks from a wide range of tectonic settings: mineral compositions in equilibrium. Contrib. Mineral. Petrol. 156, 177–195 (2008)
Shaw, D. M. Geochemistry of pelitic rocks. Part III: Major elements and general geochemistry. Geol. Soc. Am. Bull. 67, 919–934 (1956)
Pearce, J. A. Statistical analysis of major element patterns in basalts. J. Petrol. 17, 15–43 (1976)
Padrón-Navarta, J. A. et al. Tschermak’s substitution in antigorite and consequences for phase relations and water liberation in high-grade serpentinites. Lithos 178, 186–196 (2013)
Alt, J. C. & Teagle, D. A. H. The uptake of carbon during alteration of ocean crust. Geochim. Cosmochim. Acta 63, 1527–1535 (1999)
Hermann, J., Zheng, Y.-F. & Rubatto, D. Deep fluids in subducted continental crust. Elements 9, 281–287 (2013)
Tajcˇmanová, L., Connolly, J. A. D. & Cesare, B. A thermodynamic model for titanium and ferric iron solution in biotite. J. Metamorph. Geol. 27, 153–165 (2009)
Holland, T., Baker, J. & Powell, R. Mixing properties and activity-composition and relationships of chlorites in the system MgO-FeO-Al2O3-SiO2-H2O. Eur. J. Mineral. 10, 395–406 (1998)
Mahar, E. M., Baker, J. M., Powell, R., Holland, T. J. B. & Howell, N. The effect of Mn on mineral stability in metapelites. J. Metamorph. Geol. 15, 223–238 (1997)
Coggon, R. & Holland, T. J. B. Mixing properties of phengitic micas and revised garnet-phengite thermobarometers. J. Metamorph. Geol. 20, 683–696 (2002)
Auzanneau, E., Schmidt, M. W., Vielzeuf, D. & Connolly, J. D. Titanium in phengite: a geobarometer for high temperature eclogites. Contrib. Mineral. Petrol. 159, 1–24 (2010)
Waldbaum, D. R. & Thompson, J. B. Mixing properties of sanidine crystalline solutions. 2. Calculations based on volume data. Am. Mineral. 53, 2000–2017 (1968)
Holland, T. & Powell, R. Thermodynamics of order-disorder in minerals: II. Symmetric formalism applied to solid solutions. Am. Mineral. 81, 1425–1437 (1996)
White, R. W., Powell, R., Holland, T. J. B. & Worley, B. A. The effect of TiO2 and Fe2O3 on metapelitic assemblages at greenschist and amphibolite facies conditions: mineral equilibria calculations in the system K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2-Fe2O3 . J. Metamorph. Geol. 18, 497–511 (2000)
Newton, R. C., Charlu, T. V. & Kleppa, O. J. Thermochemistry of the high structural state plagioclases. Geochim. Cosmochim. Acta 44, 933–941 (1980)
Dale, J., Powell, R., White, R., Elmer, F. & Holland, T. A thermodynamic model for Ca–Na clinoamphiboles in Na2O–CaO–FeO–MgO–Al2O3–SiO2–H2O–O for petrological calculations. J. Metamorph. Geol. 23, 771–791 (2005)
Pirard, C. & Hermann, J. Experimentally determined stability of alkali amphibole in metasomatised dunite at sub-arc pressures. Contrib. Mineral. Petrol. 169, 1–26 (2015)
Hack, A. C., Thompson, A. B. & Aerts, M. Phase relations involving hydrous silicate melts, aqueous fluids, and minerals. Rev. Mineral. Geochem. 65, 129–185 (2007)
Kessel, R., Ulmer, P., Pettke, T., Schmidt, M. W. & Thompson, A. B. The water-basalt system at 4 to 6 GPa: phase relations and second critical endpoint in a K-free eclogite at 700 to 1400°C. Earth Planet. Sci. Lett. 237, 873–892 (2005)
Schmidt, M. W. & Poli, S. Experimentally based water budgets for dehydrating slabs and consequences for arc magma generation. Earth Planet. Sci. Lett. 163, 361–379 (1998)
Syracuse, E. M., van Keken, P. E. & Abers, G. A. The global range of subduction zone thermal models. Phys. Earth Planet. Inter. 183, 73–90 (2010)
Penniston-Dorland, S. C., Kohn, M. J. & Manning, C. E. The global range of subduction zone thermal structures from exhumed blueschists and eclogites: rocks are hotter than models. Earth Planet. Sci. Lett. 428, 243–254 (2015)
Connolly, J. A. D. & Cesare, B. C-O-H-S fluid composition and oxygen fugacity in graphitic metapelites. J. Metamorph. Geol. 11, 379–388 (1993)
Holland, T. & Powell, R. Activity–composition relations for phases in petrological calculations: an asymmetric multicomponent formulation. Contrib. Mineral. Petrol. 145, 492–501 (2003)
Kerrick, D. M. & Connolly, J. A. D. Metamorphic devolatilization of subducted marine sediments and the transport of volatiles into the Earth’s mantle. Nature 411, 293–296 (2001)
Kelemen, P. B. & Manning, C. E. Reevaluating carbon fluxes in subduction zones, what goes down, mostly comes up. Proc. Natl Acad. Sci. USA 112, E3997–E4006 (2015)
Caciagli, N. C. & Manning, C. E. The solubility of calcite in water at 6-16 kbar and 500-800°C. Contrib. Mineral. Petrol. 146, 275–285 (2003)
Frezzotti, M. L., Selverstone, J., Sharp, Z. D. & Compagnoni, R. Carbonate dissolution during subduction revealed by diamond-bearing rocks from the Alps. Nat. Geosci. 4, 703–706 (2011)
Helgeson, H. C., Kirkham, D. H. & Flowers, G. C. Theoretical prediction of the thermodynamic behavior of aqueous electrolytes by high pressures and temperatures; IV, Calculation of activity coefficients, osmotic coefficients, and apparent molal and standard and relative partial molal properties to 600 degrees C and 5kb. Am. J. Sci. 281, 1249–1516 (1981)
Tanger, J. C. & Helgeson, H. C. Calculation of the thermodynamic and transport properties of aqueous species at high pressures and temperatures; revised equations of state for the standard partial molal properties of ions and electrolytes. Am. J. Sci. 288, 19–98 (1988)
Helgeson, H. C. & Kirkham, D. H. Theoretical prediction of the thermodynamic behavior of aqueous electrolytes at high pressures and temperatures; II, Debye-Huckel parameters for activity coefficients and relative partial molal properties. Am. J. Sci. 274, 1199–1261 (1974)
Helgeson, H. C. & Kirkham, D. H. Theoretical prediction of the thermodynamic behavior of aqueous electrolytes at high pressures and temperatures; I, Summary of the thermodynamic/electrostatic properties of the solvent. Am. J. Sci. 274, 1089–1198 (1974)
Helgeson, H. C. & Kirkham, D. H. Theoretical prediction of the thermodynamic properties of aqueous electrolytes at high pressures and temperatures. III. Equation of state for aqueous species at infinite dilution. Am. J. Sci. 276, 97–240 (1976)
Sverjensky, D. A., Hemley, J. & d’Angelo, W. Thermodynamic assessment of hydrothermal alkali feldspar-mica-aluminosilicate equilibria. Geochim. Cosmochim. Acta 55, 989–1004 (1991)
Miron, G. D., Wagner, T., Kulik, D. A. & Heinrich, C. A. Internally consistent thermodynamic data for aqueous species in the system Na–K–Al–Si–O–H–Cl. Geochim. Cosmochim. Acta 187, 41–78 (2016)
Fernández, D. P., Mulev, Y., Goodwin, A. & Sengers, J. L. A database for the static dielectric constant of water and steam. J. Phys. Chem. Ref. Data 24, 33–70 (1995)
Fernández, D., Goodwin, A., Lemmon, E. W., Sengers, J. L. & Williams, R. A formulation for the static permittivity of water and steam at temperatures from 238 K to 873 K at pressures up to 1200 MPa, including derivatives and Debye–Hückel coefficients. J. Phys. Chem. Ref. Data 26, 1125–1166 (1997)
Bockris, J. O. M. & Reddy, A. K. N. Modern Electrochemistry: An Introduction to an Interdisciplinary Area Vol. 2 (Springer, 1973)
Landau, L. D. & Lifshitz, M. Electrodynamics of Continuous Media (Pergamon, 1960)
Looyenga, H. Dielectric constants of heterogeneous mixtures. Physica 31, 401–406 (1965)
Harvey, A. H. & Prausnitz, J. M. Dielectric constants of fluid mixtures over a wide range of temperature and density. J. Solution Chem. 16, 857–869 (1987)
Walther, J. V. Ionic association in H2O-CO2 fluids at mid-crustal conditions. J. Metamorph. Geol. 10, 789–797 (1992)
Akinfiev, N. & Zotov, A. Thermodynamic description of equilibria in mixed fluids (H2O-non-polar gas) over a wide range of temperature (25-700°C) and pressure (1-5000 bars). Geochim. Cosmochim. Acta 63, 2025–2041 (1999)
Davies, C. W. Ion Association (Butterworths, 1962)
Davies, C. W. The extent of dissociation of salts in water. Part VIII. An equation for the mean ionic activity coefficient of an electrolyte in water, and a revision of the dissociation constants of some sulphates. J. Chem. Soc. 2093–2098 (1938)
van Keken, P. E., Hacker, B. R., Syracuse, E. M. & Abers, G. A. Subduction factory: 4. Depth-dependent flux of H2O from subducting slabs worldwide. J. Geophys. Res. Solid Earth 116, B01401 (2011)
Dasgupta, R. & Hirschmann, M. M. The deep carbon cycle and melting in Earth’s interior. Earth Planet. Sci. Lett. 298, 1–13 (2010)
Thomson, A. R., Walter, M. J., Kohn, S. C. & Brooker, R. A. Slab melting as a barrier to deep carbon subduction. Nature 529, 76–79 (2016)
Connolly, J. A. D. Computation of phase equilibria by linear programming: a tool for geodynamic modeling and its application to subduction zone decarbonation. Earth Planet. Sci. Lett. 236, 524–541 (2005)
Gorman, P. J., Kerrick, D. M. & Connolly, J. A. D. Modeling open system metamorphic decarbonation of subducting slabs. Geochem. Geophys. Geosyst. 7, Q04007 (2006)
Skora, S. et al. Hydrous phase relations and trace element partitioning behaviour in calcareous sediments at subduction-zone conditions. J. Petrol. 56, 953–980 (2015)
Zhang, Z. & Duan, Z. Prediction of the PVT properties of water over wide range of temperatures and pressures from molecular dynamics simulation. Phys. Earth Planet. Inter. 149, 335–354 (2005)
Pokrovskii, V. A. & Helgeson, H. C. Thermodynamic properties of aqueous species and the solubilities of minerals at high pressures and temperatures; the system Al2O3-H2O-NaCl. Am. J. Sci. 295, 1255–1342 (1995)
Pokrovskii, V. A. & Helgeson, H. C. Thermodynamic properties of aqueous species and the solubilities of minerals at high pressures and temperatures: the system Al2O3-H2O-KOH. Chem. Geol. 137, 221–242 (1997)
Sverjensky, D. A., Shock, E. L. & Helgeson, H. C. Prediction of the thermodynamic properties of aqueous metal complexes to 1000°C and 5 kb. Geochim. Cosmochim. Acta 61, 1359–1412 (1997)
Xie, Z. & Walther, J. V. Wollastonite+ quartz solubility in supercritical NaCl aqueous solutions. Am. J. Sci. 293, 235–255 (1993)
Miron, G. D. Internally Consistent Thermodynamic Database for Fluid-Rock Interaction: Tools, Methods and Optimization. Dissertation no. 23242, ETH-Zurich (2016)
Acknowledgements
The presentation of this work benefited from informal reviews by O. Bachmann and D. Rumble. Discussions with P. Ulmer, X. Zhong, J.A. Padron Navarta, D. Miron, D. Sverjensky, J. Eiler and J. Cohen were helpful. This research was supported by an ETH fellowship ETH/CoFUND Fel-06 13-2 (M.E.G). Partial support from Carnegie and Society in Science/Branco-Weiss fellowships (M.E.G.), Swiss National Science Foundation Grant 200021_146872 (J.A.D.C), Deep Carbon Observatory and National Science Fundation grant EAR 1347987 (C.E.M) are also acknowledged.
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M.E.G. conceived the project, developed the computational tools used and performed the calculations. J.A.D.C. developed the PerpleX software used for phase equilibria computations. M.E.G., J.A.D.C. and C.E.M. analysed the data and wrote the paper.
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Reviewer Information Nature thanks D. Dolejs, K. Evans and H. Keppler for their contribution to the peer review of this work.
Extended data figures and tables
Extended Data Figure 2 Oxide chemical potential across a peridotite–crust interface.
Shown are profiles of oxide chemical potentials (μ) in the metasomatic model (Fig. 3c, d) relative to that for component at 600 °C and 2 GPa.
Extended Data Figure 3 Relative activity of selected neutral species across a serpentinite–crust interface.
Shown are relative activities of neutral polynuclear clusters , and , as well as Na+ and , in the fluid, at 600 °C and 2 GPa (see Fig. 3c, d).
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Galvez, M., Connolly, J. & Manning, C. Implications for metal and volatile cycles from the pH of subduction zone fluids. Nature 539, 420–424 (2016). https://doi.org/10.1038/nature20103
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