Models for Defining Earth's Deep Carbon Cycle

DCO’s overarching and ambitious goal is to understand all of the carbon in Earth; how it moves, where it’s stored, and how it reacts to generate energy and life. The carbon inside Earth, in the mantle and core, may represent as much as 90% of Earth’s carbon. Unlike studying the vast jungles or deserts of Earth’s surface, the expanse of deep Earth lies out of our reach. We cannot directly observe the inner workings of our planet.

Modeling, however, offers a way to go inside Earth in a virtual way. In the MELTS and DEW Synthesis project, modeling experts Mark Ghiorso (OFM Research, USA) and Dimitri Sverjensky (Johns Hopkins University, USA) are working to create a virtual laboratory. By combining two types of models, they are able to visualize and help researchers better understand how carbon moves in Earth and chemically comparable planetary bodies.

The research team is working to integrate existing thermodynamic models of magmas (MELTS) and fluids (DEW) to form a framework allowing researchers to model the mass transfer and transport of carbon and other chemical elements within Earth. Once achieved, this will be the first integrated thermodynamic model of the magma-fluid system, making it possible to predict how carbon moves between solid, liquid, and fluid phases in response to temperature and pressure inside Earth.

Uniting MELTS and DEW

Deep Earth Rock

In deep Earth, carbon moves in silicate melts and in aqueous fluids. While scientists appreciate the fact that melts and fluids can communicate chemically, how they do so is poorly understood. The MELTS and DEW model is helping to define the chemical communication between the two.

Sverjensky’s publication of the Deep Earth Water model (DEW) in 2013 has led to a deeper understanding of Earth’s tectonic activity and the evolution of our breathable atmosphere. Ghiorso developed the MELTS model over the past 20 years. It is a comprehensive model phase diagram of how minerals in deep Earth melt in response to varying temperature and pressure. Many scientists use the MELTS model, and it has led to a better and more quantitative understanding of the source regions, storage conditions, and eruptive potential of magmatic systems.

Uniting the MELTS and DEW model will result in an entirely new way of visualizing and experimenting on Earth’s interior. Ghiorso and Sverjensky have formed a small team of researchers based at OFM Research in Seattle and Johns Hopkins University in Baltimore to tackle the many technical challenges of linking these two complex models.

Integrating MELTS and DEW into one model will allow the team to start asking questions, such as “How do fluids and magmas works together to transport carbon in deep Earth, and how much carbon can Earth’s mantle accommodate?”

Across the DCO Science Communities, this work may yield answers to other specific research questions:

  • Deep Energy: Are hydrocarbons significant constituents of fluids coexisting with magmas?

  • Deep Life: Are fluids evolved from magmas at high pressures capable of transporting nutrient organic molecules to a deep biosphere?

  • Reservoirs and Fluxes: What is the exact role of carbon-bearing subduction zone fluids in the generation of magma and the return of carbon to the atmosphere?

  • Extreme Physics and Chemistry: How can we integrate simulations of deep carbon reactions with the 4D Deep Carbon in Earth Model?

Open Data, Training, Synthesis

This project is generating a huge amount of data, presented as model simulations. The team is making both the simulations and their software packages available via this website and Github. They are collaborating with DCO’s Data Science Team to innovate new ways of using large datasets and making them available for research. The combined MELTS-DEW model is also an integral component of a concurrent NSF funded project called Enabling Knowledge Integration (ENKI), which is making available to the community a wide variety of thermodynamic and computational fluid dynamic modeling tools that may be easily integrated into model simulations of Earth and other planetary processes.

Towards the end of the project, the team plans training workshops for scientists interested in using their model. With potential application in all four of DCO’s Science Communities, this software will have a lasting impact on the field of deep carbon science well into the future. 

For now, scientists can use the Deep Earth Model. The download contains two pieces of software written in Excel, and a paper describing the model. Download here.

How to Get Involved

A group of scientists have formed the “Deep Earth Water Community” to explore how fluids link deep Earth and the planet's surface. The online community offers many analytical tools and materials for advancing this vision, and ways to investigate these interactions over deep time. Downloadable products include short courses, model packages and programs, and a large bibliography of reading materials.

Getting involved



ENKI Webinar

Project Leaders

  • Dr. Mark Ghiorso
    Mark S. Ghiorso OFM Research Inc., USA
    Dr. Mark Ghiorso
    Mark S. Ghiorso
    OFM Research Inc., USA

    Dr. Mark Ghiorso is the vice president and senior research associate at OFM Research Inc. Ghiorso also serves as an affiliate professor at the University of Washington and adjoint professor at Vanderbilt University. He also serves as an associate editor for the American Journal of Science and Contributions to Mineralogy and Petrology. Ghiorso is a fellow, councilor, and distinguished lecturer of the Mineralogical Society of America, a fellow of the Geological Society of America and the American Geophysical Union. His work has been recognized with honors from the Mineralogical Society of America, European Geosciences Union, and the American Geophysical Union.

  • Dr. Dimitri Sverjensky
    Dimitri Sverjensky Johns Hopkins University, USA
    Dr. Dimitri Sverjensky
    Dimitri Sverjensky
    Johns Hopkins University, USA

    Dr. Dimitri Sverjensky is a professor in the Department of Earth and Planetary Sciences at Johns Hopkins University, where he has taught since 1984.  A geochemist, his research interests are diverse and include: deep Earth carbon, nitrogen, sulfur and water cycles, astrobiology, high temperature/pressure aqueous solution chemistry, and chemical equilibria and mass transfer.  He is a fellow of the Geochemical Society and the European Association of Geochemistry, and a recipient of the Lindgren Award from the Society of Economic Geologists.  Sverjensky is co-PI of the synthesis project MELTS and DEW.


Sverjensky and Ghiorso Host Webinar

Sverjensky and Ghiorso presented the latest advances in their effort to construct a virtual laboratory. 

MELTS and DEW Progress Report

The MELTS/DEW team is making exceptional progress.They have completed these projects: a thermodynamic model for water that extends the DEW model to magmatic pressure-temperature conditions; a software package that is code-compatible with MELTS to calculate the thermodynamics of DEW fluids; the calculation of the composition of a non-carbon bearing fluid that coexists with a magmatic solid-liquid assemblage under appropriate temperature-pressure conditions; evaluation of the internal consistency and applicability of carbonate speciation in DEW in light of recent experimental data on the properties of H2O-CO2 fluids; and calculation of the composition of an oxidized carbon bearin fluid that coexists with a magmatic solid-liquid assemblage under appropriate temperature-pressure conditions.

Mark Ghiorso webinar

Mark Ghiorso gave a webinar on "Studying Deep Earth Reactive Transport Using ENKI" on 26 July 2017. It's fun, informative, and clearly shows the power of modeling to visualize data. Watch it here.

MELTS-DEW Model Demo

Mark Ghiorso and Dimitri Sjerensky gave a demonstration of the MELTS-DEW model at DCO's Third Annual Science Meeting at the University of St. Andrews, 24 March 2017. The team showed how Jupyter notebooks could be used by individual researchers to apply the model to their own results.

Project Launch

The Principal Investigators of this ambitious project have been actively putting together the pieces that will ultimately result in the first integrated thermodynamic model of the magma-fluid system. They are currently collaborating with DCO’s Data Science Team to innovate new ways of using large datasets and making them available for research.

The combined MELTS-DEW model is also an integral component of a concurrent NSF-funded project called ENKI, which will gather together and make available to the community a wide variety of thermodynamic and computational fluid dynamic modeling tools that may be easily integrated to develop model simulations of Earth and other planetary processes.

Check back here regularly for updates as model simulations are developed.


Further Reading

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Lee, C.-T. A. et al. Continental arc‚ island arc fluctuations, growth of crustal carbonates, and long-term climate change. Geosphere 9, 21-36, (2013).

Sverjensky, D. A., Stagno, V. & Huang, F. Important role for organic carbon in subduction-zone fluids in the deep carbon cycle. Nat. Geosci. 7, 909-913, (2014).

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).

Shen, A. H. & Keppler, H. Direct observation of complete miscibility in the albite-H2O system. Nature 287, 710-712, (1997).

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Frost, D. J. & McCammon, C. A. The redox state of Earth's mantle. Annu. Rev. Earth Planet. Sci. 36, 389-420, (2008).

Hirschmann, M. M. Ironing out the oxidation of Earth's mantle. Science 325, 545-546, (2009).

Jégo, S. & Dasgupta, R. Fluid-present melting of sulfide-bearing ocean-crust: Experimental constraints on the transport of sulfur from subducting slab to mantle wedge. Geochim.Cosmochim. Acta 110, 106-134, (2013).

Brounce, M., Kelley, K. & Cottrell, E. Variations in Fe3+/Fe of Mariana Arc Basalts and Mantle Wedge fO2. Journal of Petrology 55, 2513-2536, (2014).

Brounce, M., Kelley, K. A., Cottrell, E. & Reagan, M. K. Temporal evolution of mantle wedge oxygen fugacity during subduction initiation. Geology 43, 775-778, (2015).

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Facq, S., Daniel, I. & Sverjensky, D. A. In situ Raman study and thermodynamic model of aqueous carbonate speciation in equilibrium with aragonite under subduction zone conditions. Geochim. Cosmochim. Acta132, 375-390, (2014).

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).

Pan, D., Spanu, L., Harrison, B., Sverjensky, D. A. & Galli, G. The dielectric constant of water under extreme conditions and transport of carbonates in the deep Earth. Proceedings of the National Academy of Sciences110, 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 60 kb and 1,200°C. Geochim. et Cosmochim. Acta 129, 125-145, (2014).

Sverjensky, D. A. & Huang, F. Diamond formation due to a pH drop during fluid-rock interactions. Nat .Commun. 6, (2015).

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Gualda, G. A., Ghiorso, M. S., Lemons, R. V. & Carley, T. L. Rhyolite-MELTS: a modified calibration of MELTS optimized for silica-rich, fluid-bearing magmatic systems. Journal of Petrology 53, 875-890, (2012).

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Sack, R. O. & Ghiorso, M. S. Thermodynamics of multicomponent pyroxenes: I. Formulation of a general model. Contributions to Mineralogy and Petrology 116, 277-286, (1994).

Sack, R. O. & Ghiorso, M. S. Thermodynamics of multicomponent pyroxenes: II. Phase relations in the quadrilateral. Contributions to Mineralogy and Petrology116, 287-300, (1994).

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Ghiorso, M. S. & Kress, V. C. An equation of state for silicate melts. II. Calibration of volumetric properties at 105 Pa. American Journal of Science 304, 679-751, (2004).

Ghiorso, M. & Carmichael, I. Chemical mass-transfer in magmatic processes. 2. Applications in equilibrium crystallization, fractionation and assimilation. Contributions to Mineralogy and Petrology 90, 121-141, (1985).

Ghiorso, M. S. Algorithms for the estimation of phase stability in heterogeneous thermodynamic systems. Geochim. Cosmochim. Acta 58, 5489-5501, (1994).

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Ghiorso, M. & Gualda, G. Chemical thermodynamics and the study of magmas. Encyclopedia of Volcanoes. Elsevier, 143-161, (2015).

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Shock, E. L., Helgeson, H. C. & Sverjensky, D. A. Calculation of the thermodynamic and transport properties of aqueous species at high pressures and temperatures: Standard partial molal properties of inorganic neutral species. Geochim. Cosmochim. Acta53, 2157-2184, (1989).

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Sverjensky, D. A. Physical surface-complexation models for sorption at the mineral-water interface. Nature 364, 776-780, (1993).

Sverjensky, D. A. Zero-point-of-charge prediction from crystal chemistry and solvation theory. Geochim. Cosmochim. Acta 58, 3123-3129, (1994).

Sverjensky, D. A., Shock, E. L. & Helgeson, H. C. Prediction of the thermodynamic properties of aqueous metal complexes to 1,000 °C and 5.0 kb. Geochim. Cosmochim. Acta 61, 1359-1412, (1997).

Zhu, C. & Sverjensky, D. A. Partitioning of F, Cl, and OH between minerals and hydrothermal fluids. Geochim. Cosmochim. Acta 55, 1837-1858, (1991).

Sverjensky, D. A. Oil-field brines as ore-forming solutions. Econ. Geol. 79, 23-37, (1984).

Sverjensky, D. A. The role of migrating oil-field brines in the formation of sediment-hosted Curich deposits. Econ.Geol. 82, 1130-1141, (1987).

Sverjensky, D. A. The diverse origins of Mississippi Valley-type Zn-Pb-Ba-F deposits. Chron.Rech. Min. 495, 5-13, (1989).

Fukushi, K. & Sverjensky, D. A. A predictive model for arsenate adsorption and surface speciation on oxides consistent with spectroscopic and theoretical molecular evidence. Geochim. Cosmochim. Acta 71, 3717-3745, (2007).

Sverjensky, D. A. & Fukushi, K. A predictive model (ETLM) for As(III) adsorption and surface speciation on oxides consistent with spectroscopic data. Geochim. Cosmochim. Acta 70, 3778- 3802, (2006).

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Ghiorso, M. S. & Gualda, G. A. An H2O-CO2 mixed fluid saturation model compatible with rhyolite-MELTS. Contributions to Mineralogy and Petrology 169, 1-30, (2015).

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