MELTS and DEW

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MELTS and DEW

Models create a virtual carbon laboratory

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.  
Uniting MELTS and DEW
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.

Near the summit of the Tongariro crossing in Tongariro National Park, North Island, New Zealand.Credit: Mark Ghiorso.

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?

Dimitri Sverjensky at St. Andrews, UK.

Open data, training, cross-community synthesis
This project will generate a huge amount of data, presented as model simulations. The team will make 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 will also be an integral component of a concurrent NSF funded project called Enabling Knowledge Integration (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.
Towards the end of the project, the team will also offer 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.

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.


Team Leaders

ghiorso@ofm-research.org(Mark Ghiorso) has spent his research career developing physical and chemical models of minerals, fluids and silicate melts, applying these models to gain a deeper understanding of magmatic evolution and chemical differentiation within the Earth. He has published extensively on thermochemical modeling of mineral solid solutions and magmas, being the principal architect of MELTS, an open-source software framework that is widely used in modeling equilibrium crystallization, crystal fractionation and assimilation in magmatic systems. As part of research conducted with funding provided by DCO’s Extreme Physics and Chemistry Community, Ghiorso extended the MELTS framework to include models of carbon solubility in natural magmatic liquids, an important first step in our quantitative understanding of carbon transport by igneous processes.

 

sver@jhu.edu (Dimitri Sverjensky) has spent his research and teaching career investigating the way water interacts with rocks and minerals. He has particularly focused on building open-source predictive models of the behavior of aqueous species in water over a wide range of conditions from the near surface environment to depths of the upper mantle in Earth. These models have been applied to the practical understanding of the formation of economically important lead, zinc, and copper deposits, the migration of toxic elements such as arsenic in the environment, the role of minerals and water in the origin of life, the deep occurrence of aqueous organic species in subduction zones, the origin of nitrogen in planetary atmospheres, and a new role for water-rock interactions in the origin of diamonds.


Downloads

The Deep Earth Model is available for download. The download contains two pieces of software written in Excel, and a paper describing the model.


Updates

21 September, 2017
Darlene Trew Crist, Synthesis Group 2019 manager

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.

24 February, 2017
Darlene Trew Crist, Synthesis Group 2019 manager

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.

2 November, 2016
Darlene Trew Crist, Synthesis Group 2019 manager

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).

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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 Sciences 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 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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