4D quantification of micro-scale feedbacks in dehydrating, deforming rocks
Lead Research Organisation:
University of Edinburgh
Department Name: Sch of Geosciences
Abstract
This research project uses a novel methodological approach to determine where mineral dehydration reactions can trigger failure in deforming rocks. This link between dehydration and failure is important at convergent plate boundaries. Where plates collide, the shallow portions of the Earth's crust are affected by so-called thin-skinned tectonics. There, dehydration reactions enable the emplacement of tectonic nappes, which shape mountain belts such as the Swiss Jura, or the Appalachians in the US. Plate collision also leads to the subduction of tectonic plates, where dehydration reactions are suspected to trigger seismic events at depths of several tens of kilometers. In both tectonic settings hydrous minerals in rocks become unstable as temperature increases. They start to transform into denser minerals by releasing water in dehydration reactions. The density increase produces pores, which are filled by the water. The pores, the fluid pressure in them, and the newly grown minerals weaken the reacting rock mechanically. It may become unable to support tectonic stresses and fail.
The processes that control large-scale tectonics start at the grain scale. These grain scale processes entail a series of complicated, intertwined developments that involve the chemistry, hydraulics and mechanics of a dehydrating rock. Coupled chemical, hydraulic and mechanical processes may facilitate the self-organization of the dehydrating rock into a state where it ultimately fails. Unfortunately, neither classical laboratory experiments nor field-based studies allow a spatial and temporal (4D) characterization of these coupled processes on the micro-scale. Models to explain failure in dehydrating rocks therefore lack a robust observational basis.
We will use a unique combination of new methods to overcome this severe limitation. Our interdisciplinary team of experienced researchers will establish a technique to directly observe dehydration reactions in deforming rocks. We will employ the most powerful x-ray sources in the UK and Switzerland to observe dehydration reactions in a new generation of experimental pressure vessels. These vessels are transparent to x-rays and allow us to reproduce conditions at the base of tectonic nappes and at intermediate depths in subduction zones. They are designed and built in Edinburgh. Combining these vessels with time-resolved (4D) x-ray microtomography will enable us to document mineral dehydration at a wide range of conditions. The resulting 4D microtomography data sets will have a volume of several tens of TB. New analysis techniques based on machine learning will allow us to extract the relevant information from these vast quantities of data. Our analyses will determine conditions where dehydration causes rocks to become unable to support tectonic stresses. Using these analyses, we will test and advance theoretical concepts used to link dehydration and deformation in numerical simulations.
The first direct observation of the complex grain-scale developments during dehydration reactions will significantly advance our understanding of some key processes in tectonics. Because our data are time-resolved and dynamic, they will support the interpretation of field data that otherwise capture a static, fossilized picture of dehydration reactions. Our data will allow testing and refining existing mathematical models that provide a foundation for robust simulations of large-scale tectonic processes. Ultimately, our findings will support the assessment of risks associated with plate collision. Our project will also make a new experimental imaging method available for research on geothermal energy, CO2 sequestration and nuclear waste storage. The method combines time-resolved x-ray microtomography in our new experimental vessels with advanced data mining and image analysis and computational simulation.
The processes that control large-scale tectonics start at the grain scale. These grain scale processes entail a series of complicated, intertwined developments that involve the chemistry, hydraulics and mechanics of a dehydrating rock. Coupled chemical, hydraulic and mechanical processes may facilitate the self-organization of the dehydrating rock into a state where it ultimately fails. Unfortunately, neither classical laboratory experiments nor field-based studies allow a spatial and temporal (4D) characterization of these coupled processes on the micro-scale. Models to explain failure in dehydrating rocks therefore lack a robust observational basis.
We will use a unique combination of new methods to overcome this severe limitation. Our interdisciplinary team of experienced researchers will establish a technique to directly observe dehydration reactions in deforming rocks. We will employ the most powerful x-ray sources in the UK and Switzerland to observe dehydration reactions in a new generation of experimental pressure vessels. These vessels are transparent to x-rays and allow us to reproduce conditions at the base of tectonic nappes and at intermediate depths in subduction zones. They are designed and built in Edinburgh. Combining these vessels with time-resolved (4D) x-ray microtomography will enable us to document mineral dehydration at a wide range of conditions. The resulting 4D microtomography data sets will have a volume of several tens of TB. New analysis techniques based on machine learning will allow us to extract the relevant information from these vast quantities of data. Our analyses will determine conditions where dehydration causes rocks to become unable to support tectonic stresses. Using these analyses, we will test and advance theoretical concepts used to link dehydration and deformation in numerical simulations.
The first direct observation of the complex grain-scale developments during dehydration reactions will significantly advance our understanding of some key processes in tectonics. Because our data are time-resolved and dynamic, they will support the interpretation of field data that otherwise capture a static, fossilized picture of dehydration reactions. Our data will allow testing and refining existing mathematical models that provide a foundation for robust simulations of large-scale tectonic processes. Ultimately, our findings will support the assessment of risks associated with plate collision. Our project will also make a new experimental imaging method available for research on geothermal energy, CO2 sequestration and nuclear waste storage. The method combines time-resolved x-ray microtomography in our new experimental vessels with advanced data mining and image analysis and computational simulation.
Planned Impact
Our technology-led proposal will directly benefit industry and governmental stakeholders in their R&D. We will establish a new experimental technique at the Diamond Light Source that is uniquely suited to observe and document fluid-rock interaction at the grain scale. Such processes are at the core of geothermal heat extraction, CO2 sequestration and nuclear waste storage. The chemical-hydraulic-mechanical interactions involved are further relevant for applied concrete research and the processing of industrial minerals. Time-resolved (4D) in-situ microtomography experiments provide unprecedented insights into grain-scale developments that impact on these operations on larger scales. The legacy cell will be transferred to Diamond at the end of our project, with staff being trained in its use during our project-specific work at Diamond.
Industry will also benefit from the publications of the technical drawings of our cell. As we have done with other rigs previously [Refs. 4,7], we will do this to encourage reproduction and improvement by third parties once the final design is tried and tested. In this way, our x-ray transparent fluid-rock interaction cell "Sleipnir" was copied and is now used by an oil & gas research centre in Pau (France) and by an applied research group at Stanford University (USA), and available to general users at the Advanced Photon Source (USA).
Data analysis is generally the bottle neck in 4D x-ray imaging, mostly due to the significant volumes of data involved and the variety of codes available for different tasks. At Diamond, we will also establish a new data acquisition protocol that reduces the amount of waste data and thereby facilitates data processing and analysis. We will also devise a new data processing and analysis framework that combines and optimizes a range of available codes and integrates novel data mining algorithms. All of these codes are open source. Towards the end of our project, once tried and tested, this framework will be freely shared on Github. Both actions will reduce the time from experiment to result and support the uptake of 4D x-ray microtomography by a wider R&D community.
The general public will benefit from our outreach activities during the project. In our interdisciplinary research we will utilize one of the UK's flagship research facilities to conduct pioneering and challenging experimental work that will push limits both on the geosciences side, the synchrotron imaging side and the data analysis end. During the project, ongoing work will be disseminated through social media and a project-specific blog on our departmental website. We will further embed 4th undergraduate students on our "Geoscience Outreach" course in our synchrotron campaigns, where they will a) experience cutting edge science in action first hand and b) communicate their experience through their outreach projects. This can involve organising sessions with school children to highlight UK research and encourage careers in science, entertaining blogs and webpages and feeding into Facebook and Twitter.
We will show our science output at Diamond's open days. These attract several thousand visitors every year. The principal ideas and achievements and their relevance will be shown in
displays in Diamond House, where one or two of our researchers will be present to answer questions before and after visitors go on tours through the synchrotron.
As a source of information that lasts beyond the duration of the project, we will establish two displays for the Cockburn Museum at the Grant Institute of Geology (Edinburgh). These will 1) detail the interdisciplinary methodological approach of our research project, which spans geosciences, informatics and engineering, and 2) illustrate the most important research data and results for highlight the significance of micro-scale processes for plate tectonics. During "Doors Open" days, these displays will be staffed and presented to the public.
Industry will also benefit from the publications of the technical drawings of our cell. As we have done with other rigs previously [Refs. 4,7], we will do this to encourage reproduction and improvement by third parties once the final design is tried and tested. In this way, our x-ray transparent fluid-rock interaction cell "Sleipnir" was copied and is now used by an oil & gas research centre in Pau (France) and by an applied research group at Stanford University (USA), and available to general users at the Advanced Photon Source (USA).
Data analysis is generally the bottle neck in 4D x-ray imaging, mostly due to the significant volumes of data involved and the variety of codes available for different tasks. At Diamond, we will also establish a new data acquisition protocol that reduces the amount of waste data and thereby facilitates data processing and analysis. We will also devise a new data processing and analysis framework that combines and optimizes a range of available codes and integrates novel data mining algorithms. All of these codes are open source. Towards the end of our project, once tried and tested, this framework will be freely shared on Github. Both actions will reduce the time from experiment to result and support the uptake of 4D x-ray microtomography by a wider R&D community.
The general public will benefit from our outreach activities during the project. In our interdisciplinary research we will utilize one of the UK's flagship research facilities to conduct pioneering and challenging experimental work that will push limits both on the geosciences side, the synchrotron imaging side and the data analysis end. During the project, ongoing work will be disseminated through social media and a project-specific blog on our departmental website. We will further embed 4th undergraduate students on our "Geoscience Outreach" course in our synchrotron campaigns, where they will a) experience cutting edge science in action first hand and b) communicate their experience through their outreach projects. This can involve organising sessions with school children to highlight UK research and encourage careers in science, entertaining blogs and webpages and feeding into Facebook and Twitter.
We will show our science output at Diamond's open days. These attract several thousand visitors every year. The principal ideas and achievements and their relevance will be shown in
displays in Diamond House, where one or two of our researchers will be present to answer questions before and after visitors go on tours through the synchrotron.
As a source of information that lasts beyond the duration of the project, we will establish two displays for the Cockburn Museum at the Grant Institute of Geology (Edinburgh). These will 1) detail the interdisciplinary methodological approach of our research project, which spans geosciences, informatics and engineering, and 2) illustrate the most important research data and results for highlight the significance of micro-scale processes for plate tectonics. During "Doors Open" days, these displays will be staffed and presented to the public.
Organisations
Publications
Beaugnon F
(2022)
From atom level to macroscopic scale: Structural mechanism of gypsum dehydration
in Solid State Sciences
Freitas D
(2024)
Heitt Mjölnir: a heated miniature triaxial apparatus for 4D synchrotron microtomography.
in Journal of synchrotron radiation
Gilgannon J
(2023)
Elastic stresses can form metamorphic fabrics
in Geology
Marone F
(2020)
Time Resolved in situ X-Ray Tomographic Microscopy Unraveling Dynamic Processes in Geologic Systems
in Frontiers in Earth Science
Marti S
(2021)
Time-resolved grain-scale 3D imaging of hydrofracturing in halite layers induced by gypsum dehydration and pore fluid pressure buildup
in Earth and Planetary Science Letters
Description | The past year saw the completion of the experimental programme, some further experiments that prepare upcoming grant applications and the publication of three papers directly resulting from the grant (Freitas et al., Rizzo et al., and Gilgannon et al.). The Heitt Mjölnir Rig, which was built in WP2 is now frequently used in various research collaborations. The extremely successful experiments in WP1 provide transformative insights into metamorphic dehydration reactions, which are characterised by substantial volume changes and the production of large amounts of porosity. Several of the findings were unexpected: 1) The reacted rock aggregate is significantly stronger than anticipated, 2) Contrary to established models, which invoke significant strains, stress along can control the formation of a fabric in rocks, 3) the permeability during dehydration reactions evolves highly anisotropically. In the last phase of the project before its completion, we ran a series of experiments that expanded WP1 to rehydration reactions. These data are currently analysed as part of a NERC DTP funded PhD project (E Vass-Payne). |
Exploitation Route | Heitt Mjölnir is being made available to a wide range of users financed through the EU's Horizon programme "Research infrastructure services to enable R&I addressing main challenges and EU priorities" as part of the EXCITE2 consortium. We have an agreement in principle to enable use of the rig and support users at the French SOLEIL synchroton (PSICHÈ beamline) for the EXCITE2 consortium. A copy of the rig will also be built at the Advanced Photon Source's 13BM beamline, where it will become available to North American users. Besides the original copy we built as part of this grant, two further copies of the rig are now available at RWTH Aachen University (Germany) and Utrecht University (Netherlands) for easy use at European Synchrotron light sources. |
Sectors | Construction Energy Environment |
Title | A new x-ray transparent triaxial deformation rig "Heitt Mjölnir" |
Description | The physico-chemical evolution of materials that react at different temperatures, pressures and stress conditions is central to many science- and engineering problems. Metamorphic hydration and dehydration reactions are among the most tectonically significant examples of rock transformations with large volume variations and associated changes of hydraulic, chemical and mechanical rock properties. The micro-scale documentation of reaction progress and the involved feedbacks between chemical, physical and hydraulic processes using synchrotron-based 4D in-situ x-ray microtomography promises to critically advance our understanding of geological field evidence and geophysical observations. We have developed a new internally heated x-ray transparent triaxial deformation apparatus Heitt Mjolnir to study metamorphic reactions involving fluids: at confining pressure up to 30 MPa, differential axial stress > 50 MPa, controlled pore fluid pressures and temperature up to 350°C. |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2021 |
Provided To Others? | Yes |
Impact | This cell has been successfully deployed at the TOMCAT beamline at the Swiss Light Source, to perform various fluid-rock interaction experiments including calcite replacement by hydroxy-apatite and mineral dehydration (gypsum to basanite transformation as well as serpentinite, lizardite + brucite à olivine + talc) at a range of conditions. While the cell can simulate a wide variety of geological reservoirs, various applications in material sciences are also foreseen. |
Description | "How x-rays and neutrons allow us to challenge established concepts in tectonics", January 2022, Edinburgh Geological Society. |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Presentation the Edinburgh Geological Society |
Year(s) Of Engagement Activity | 2022 |
URL | https://www.youtube.com/watch?v=fsCZ72mg4M0 |
Description | "In-situ x-ray imaging of geological processes" |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited presentation at the Cornell High Energy Synchrotron Source (CHESS) workshop "Engineering, Structural, and Geological Materials from Processing to Performance", Cornell, USA. |
Year(s) Of Engagement Activity | 2021 |
Description | "Revisiting Heard & Rubey (1966) - new insights on dehydration-induced hydrofracturing in layered evaporites from in-situ 4D imaging experiment" |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited presentation at the "Interplay between mineral reactions and deformation" workshop, September 2020, Heidelberg, Germany |
Year(s) Of Engagement Activity | 2020 |
Description | "The Norse arsenal - X-ray- and neutron-transparent cells to study fluid-rock interaction and rock deformation built in Edinburgh", November 2021, University of Applied Sciences Upper Austria. |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Presentation for the Research Group Computed Tomography at the University of Applied Sciences Upper Austria. |
Year(s) Of Engagement Activity | 2021 |
Description | Invited presentation at NSF Research Coordination Network "In-situ Studies of Rock Deformation" workshop at CHESS |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited presentation explaining the current range of x-ray and neutron transparent experimental cells available at Edinburgh Geoscience Microtomography at the IN-SITU STUDIES OF ROCK DEFORMATION NSF RESEARCH COORDINATION NETWORK WORKSHOP at CHESS in June 2020. |
Year(s) Of Engagement Activity | 2020 |
URL | https://www.isrdrcn.org/workshops/chess-workshop-agenda/ |