Periodic Reporting for period 3 - MAGMA (Melting And Geodynamic Models of Ascent)
Período documentado: 2021-10-01 hasta 2023-03-31
The production and migration of magma through the lithosphere results in spectacular geological processes such as volcanic eruptions, giant ore deposits, large magmatic intrusions, and is responsible for the formation of continents on Earth.
Since magmatic systems develop on timescales of millions of years and are not directly accessible, we have to reconstruct them indirectly, such as by studying exhumed magmatic intrusions, or by using geophysical methods. Interpreting these data is complicated, as geophysical techniques only give a present-day snapshot, whereas the geological record yields an incomplete picture of the underlying processes. As a result, most existing ideas on how magmatic systems work remain conceptual and are not necessarily consistent with the mechanics of the lithosphere, which hampers our understanding of such processes.
Here, we will develop and employ a new generation of computer models to simulate the full magmatic system in arcs in a self-consistent manner, while taking both realistic rock rheologies and evolving melt chemistry into account.
We will:
1. Derive mechanically-consistent interpretations of active magmatic plumbing systems by combining geophysical and petrological data with geodynamic inverse models.
2. Develop new software tools to simulate melting and crystallisation of rocks and incorporate the evolving chemistry into computer models, such that model predictions can directly be compared with geological observations
3. Develop new software tools to simulate magma migration through deforming visco-elasto-plastic rocks
4. Obtain insights into the physics of magma migration through arcs on geological timescales, by combining numerical simulations with geological constraints from exhumed arc roots, and by targeting several well-studied magmatic intrusions.
5. Unravel how magmatic arcs are built on geological timescales, what the role and the rates of magmatic differentiation processes are in this, and how this may have formed continental crust on Earth.
We can thus, for the first time, interpret the available data in a physically consistent manner. This will give deep insights in how magmatic systems develop over geological timescales and why only some evolve into large super-volcanoes.
Since magmatic systems develop on timescales of millions of years and are not directly accessible, we have to reconstruct them indirectly, such as by studying exhumed magmatic intrusions, or by using geophysical methods. Interpreting these data is complicated, as geophysical techniques only give a present-day snapshot, whereas the geological record yields an incomplete picture of the underlying processes. As a result, most existing ideas on how magmatic systems work remain conceptual and are not necessarily consistent with the mechanics of the lithosphere, which hampers our understanding of such processes.
Here, we will develop and employ a new generation of computer models to simulate the full magmatic system in arcs in a self-consistent manner, while taking both realistic rock rheologies and evolving melt chemistry into account.
We will:
1. Derive mechanically-consistent interpretations of active magmatic plumbing systems by combining geophysical and petrological data with geodynamic inverse models.
2. Develop new software tools to simulate melting and crystallisation of rocks and incorporate the evolving chemistry into computer models, such that model predictions can directly be compared with geological observations
3. Develop new software tools to simulate magma migration through deforming visco-elasto-plastic rocks
4. Obtain insights into the physics of magma migration through arcs on geological timescales, by combining numerical simulations with geological constraints from exhumed arc roots, and by targeting several well-studied magmatic intrusions.
5. Unravel how magmatic arcs are built on geological timescales, what the role and the rates of magmatic differentiation processes are in this, and how this may have formed continental crust on Earth.
We can thus, for the first time, interpret the available data in a physically consistent manner. This will give deep insights in how magmatic systems develop over geological timescales and why only some evolve into large super-volcanoes.
A significant contribution of this project is to develop open-access software to simulate magmatic processes, such that the wider geoscience community will benefit from them (also after the end of MAGMA). This implies that the software should work on parallel machines, but also that it should be reasonably easy to use, and create setups for a particular region. We have already made significant progress towards this.
Ongoing and finished development evolves around four themes:
1) Development of inverse modelling approaches. We have extended our existing open-source 3D geodynamic modelling software (LaMEM), to take adjoint-based sensitivity analysis and gradient-based inversion into account. This makes it easier for new users to automatically test the key model parameters that, for example, affect surface uplift in a volcano. We have also developed new ways to automatically change the geometry for which we invert, and an application of these approach to the Puna magmatic system allowed us to create a very good fit to the observed gravity and uplift data (and showed the power of performing a sensitivity analysis, as it greatly reduces the number of parameters to be tested).
2) We are developing a new, massively parallel, software package to perform thermodynamic Gibbs energy minimization calculations to simulate the evolving chemistry of (partially molten) rocks that takes the latest thermodynamic hydrous mafic melting models into account. This approach should in principle be able to replace the most widely employed current software packages (Perple_X, pMELTS, Theriak-Domino), while being faster. These previous codes can currently not directly be coupled to geodynamic codes as they are too slow. The expectation is that our new code, which employs a different computational method to do the Gibbs energy minimisation, will overcome this or can be efficiently combine with machine learning approaches to achieve this goal.
3) In addition to this, we have developed new approaches to couple thermodynamic and geodynamic models, using the "classical" (and slow) thermodynamic modelling approaches but with a large database of precomputed diagrams. This allowed tracking the evolving chemistry and making testable predictions that can directly be compared with observations.
4) We are developing new, two-phase flow software package that takes visco-elasto-plasticity into account, as well as new codes that will make it easier to take multiphysics coupling into account for more general geoscience problems. We focus on both pseudo-transient modelling approaches which work particularly well on GPU architectures, as well as on implicit modelling approaches that run on MPI-parallel machines. A specific goal is to make it easy for non-experts to use such models.
Apart from the technical developments listed above, we have applied a first generation of (highly simplified) models to simulate and understand the chemical and mechanical evolution of magmatic arcs, and applied inverse modelling approaches to interpret the present-day magmatic system of the Puna area in a mechanically consistent manner. We also employed models to address the magmatism in the early Earth.
Ongoing and finished development evolves around four themes:
1) Development of inverse modelling approaches. We have extended our existing open-source 3D geodynamic modelling software (LaMEM), to take adjoint-based sensitivity analysis and gradient-based inversion into account. This makes it easier for new users to automatically test the key model parameters that, for example, affect surface uplift in a volcano. We have also developed new ways to automatically change the geometry for which we invert, and an application of these approach to the Puna magmatic system allowed us to create a very good fit to the observed gravity and uplift data (and showed the power of performing a sensitivity analysis, as it greatly reduces the number of parameters to be tested).
2) We are developing a new, massively parallel, software package to perform thermodynamic Gibbs energy minimization calculations to simulate the evolving chemistry of (partially molten) rocks that takes the latest thermodynamic hydrous mafic melting models into account. This approach should in principle be able to replace the most widely employed current software packages (Perple_X, pMELTS, Theriak-Domino), while being faster. These previous codes can currently not directly be coupled to geodynamic codes as they are too slow. The expectation is that our new code, which employs a different computational method to do the Gibbs energy minimisation, will overcome this or can be efficiently combine with machine learning approaches to achieve this goal.
3) In addition to this, we have developed new approaches to couple thermodynamic and geodynamic models, using the "classical" (and slow) thermodynamic modelling approaches but with a large database of precomputed diagrams. This allowed tracking the evolving chemistry and making testable predictions that can directly be compared with observations.
4) We are developing new, two-phase flow software package that takes visco-elasto-plasticity into account, as well as new codes that will make it easier to take multiphysics coupling into account for more general geoscience problems. We focus on both pseudo-transient modelling approaches which work particularly well on GPU architectures, as well as on implicit modelling approaches that run on MPI-parallel machines. A specific goal is to make it easy for non-experts to use such models.
Apart from the technical developments listed above, we have applied a first generation of (highly simplified) models to simulate and understand the chemical and mechanical evolution of magmatic arcs, and applied inverse modelling approaches to interpret the present-day magmatic system of the Puna area in a mechanically consistent manner. We also employed models to address the magmatism in the early Earth.
The thermodynamic and geodynamic software packages we are working on go well beyond the current state of the art of the community. We expect to be able to finish these technical developments and release the various package as open-source tools, which will significantly simplify creating geodynamic simulations. We also plan to further apply the models to simulate aspects of the magmatic system as outlined in the grant agreement.