Periodic Reporting for period 2 - nanoEARTH (The nanoscale control of reactive fluids on geological processes within the solid Earth)
Período documentado: 2021-06-01 hasta 2022-11-30
Fluid-driven mineral reactions chemically modify enormous portions of the solid Earth beneath our feet. These reactions drive fluid-mediated rock transformation processes that govern the stability of mountain belts, the formation of hydrothermal mineral deposits, the sequestration of anthropogenic carbon dioxide, and many other processes. The nanoEARTH project investigates, contrary to our current thinking, how self-promoting nanoscale transport phenomena drive mineral reactions themselves.
Existing geological frameworks lack a quantitative understanding of the mechanisms that control the rates of reactive fluid-rock interaction. This is because they do not account for the pervasive influence of nanoscale dynamics on the redistribution of elements within geological materials. The nanoEARTH project will solve this by defining the predominant transport processes occurring in mineral nanopores and the dynamic behaviour of fluid-rock interaction.
To achieve the nanoEARTH aims and break through current limitations in our understanding of fluid-rock interaction, the project team combines novel nanoscale experiments that establish transport mechanisms through natural and synthetic mineral nanopores and observations of fluid-driven mineral transformations at multiple length scales with numerical transport simulations that are constrained by geological observations.
The project is defined in four major objectives that reflect four work packages:
Objective 1: Quantify the correlative behaviour of fluid pathways and mass transport across scales.
Objective 2: Determine the mechanisms of electrokinetic transport through mineral nanopores and the influence of changes in fluid chemistry.
Objective 3: Quantify the dynamical evolution of transport pathways during fluid-driven mineral reactions.
Objective 4: Define a molecular- to continuum-scale model to assess and predict rates of fluid-driven mineral transformation and associated mass transport.
Through this strategy, the nanoEARTH team delivers new knowledge to redefine how the reaction of fluids with minerals self-generates a mode of transport that mobilizes elements and controls the rates of fluid-driven transformation. This will impact geoscience research well beyond the project duration and brings the nanoscience of geological processes a quantum leap forward.
Existing geological frameworks lack a quantitative understanding of the mechanisms that control the rates of reactive fluid-rock interaction. This is because they do not account for the pervasive influence of nanoscale dynamics on the redistribution of elements within geological materials. The nanoEARTH project will solve this by defining the predominant transport processes occurring in mineral nanopores and the dynamic behaviour of fluid-rock interaction.
To achieve the nanoEARTH aims and break through current limitations in our understanding of fluid-rock interaction, the project team combines novel nanoscale experiments that establish transport mechanisms through natural and synthetic mineral nanopores and observations of fluid-driven mineral transformations at multiple length scales with numerical transport simulations that are constrained by geological observations.
The project is defined in four major objectives that reflect four work packages:
Objective 1: Quantify the correlative behaviour of fluid pathways and mass transport across scales.
Objective 2: Determine the mechanisms of electrokinetic transport through mineral nanopores and the influence of changes in fluid chemistry.
Objective 3: Quantify the dynamical evolution of transport pathways during fluid-driven mineral reactions.
Objective 4: Define a molecular- to continuum-scale model to assess and predict rates of fluid-driven mineral transformation and associated mass transport.
Through this strategy, the nanoEARTH team delivers new knowledge to redefine how the reaction of fluids with minerals self-generates a mode of transport that mobilizes elements and controls the rates of fluid-driven transformation. This will impact geoscience research well beyond the project duration and brings the nanoscience of geological processes a quantum leap forward.
Work performed to address O1:
The COVID-19 pandemic did not allow for fieldwork in areas of interest in 2020 and 2021. Existing rock samples from several repositories were used to initiate the correlative microscopy workflow. Multi-scale X-ray and electron microscopy imaging was employed and combined with a novel machine-learning approach to quantify the correlative behaviour of fluid pathways. We have combined generative adversarial networks with novel mathematical descriptions of microstructures to overcome sparse data sampling and to quantify the multi-scale nature of pore spaces in hydrothermally altered rocks of the Earth’s middle crust and uppermost mantle. The first results are currently (July 2022) under review and a preprint is available (Amiri et al. 2022, EarthArXiv). The results have also been presented at conferences in 2021 and 2022. In a subsequent effort, the nanoEarth team is working on combining microscopy datasets at different spatial length scales and dimensions (2D electron microscopy vs. 3D X-ray tomography) to obtain a multi-scale representation of the overall porosity in hydrothermally altered rocks. As reaction-induced porosity is transiently connected, the nanoEARTH team is working on a novel machine-learning-based solution to reconnect pore space via the input from in situ experiments (O3) and numerical fluid flow simulations. A publication is expected in 2023. Finally, in collaboration, we combined natural observations and thermodynamic simulations to investigate how grain boundaries guide reactive fluid flow (Zertani et al. 2022, CMP) and volume changes during mineral reactions affect stress distributions and permeability of crystalline rocks (Schmalholz et al. 2020, G3; Plümper et al. 2022, Geology).
Work performed to address O2:
A theoretical framework for calculating the dielectric constant of nanoconfined fluids was established and implemented into molecular dynamics simulations. Results show a strong dependence of the dielectric constant upon nano-confinement under natural conditions. The results are currently transferred into thermodynamic simulation packages to evaluate the impact on mineral solubility and fluid speciation. Moreover, a novel electron microscopy strategy was developed to image and analyse nanoporosity in serpentinites. The results were presented at conferences in 2021 and 2022. We are currently working on using TEM nanotomography to quantify the connectivity of nanoporosity in serpentinites. Two manuscripts are in preparation.
Work performed to address O3:
Novel in situ 4D (3D plus time) synchrotron X-ray tomography experiments using a reactive salt system have been carried out at the Swiss Light Source (Paul Scherrer Institute). In total ten experiments have been conducted with an overall data volume of more than 20 TB. The data is being analysed using advanced image analysis algorithms that allow the treatment of large correlative data sets. The nanoEARTH team is implementing mathematical microstructural descriptions developed in O1 to further analyse the evolution of the reaction-induced pore space and couple this to transfer machine-learning algorithms to predict porosity and permeability evolutions.
Work performed to address O4:
First theoretical steps towards combining molecular- and continuum-scale models have been taken, but this objective is part of the plan for 2023 and onwards.
The COVID-19 pandemic did not allow for fieldwork in areas of interest in 2020 and 2021. Existing rock samples from several repositories were used to initiate the correlative microscopy workflow. Multi-scale X-ray and electron microscopy imaging was employed and combined with a novel machine-learning approach to quantify the correlative behaviour of fluid pathways. We have combined generative adversarial networks with novel mathematical descriptions of microstructures to overcome sparse data sampling and to quantify the multi-scale nature of pore spaces in hydrothermally altered rocks of the Earth’s middle crust and uppermost mantle. The first results are currently (July 2022) under review and a preprint is available (Amiri et al. 2022, EarthArXiv). The results have also been presented at conferences in 2021 and 2022. In a subsequent effort, the nanoEarth team is working on combining microscopy datasets at different spatial length scales and dimensions (2D electron microscopy vs. 3D X-ray tomography) to obtain a multi-scale representation of the overall porosity in hydrothermally altered rocks. As reaction-induced porosity is transiently connected, the nanoEARTH team is working on a novel machine-learning-based solution to reconnect pore space via the input from in situ experiments (O3) and numerical fluid flow simulations. A publication is expected in 2023. Finally, in collaboration, we combined natural observations and thermodynamic simulations to investigate how grain boundaries guide reactive fluid flow (Zertani et al. 2022, CMP) and volume changes during mineral reactions affect stress distributions and permeability of crystalline rocks (Schmalholz et al. 2020, G3; Plümper et al. 2022, Geology).
Work performed to address O2:
A theoretical framework for calculating the dielectric constant of nanoconfined fluids was established and implemented into molecular dynamics simulations. Results show a strong dependence of the dielectric constant upon nano-confinement under natural conditions. The results are currently transferred into thermodynamic simulation packages to evaluate the impact on mineral solubility and fluid speciation. Moreover, a novel electron microscopy strategy was developed to image and analyse nanoporosity in serpentinites. The results were presented at conferences in 2021 and 2022. We are currently working on using TEM nanotomography to quantify the connectivity of nanoporosity in serpentinites. Two manuscripts are in preparation.
Work performed to address O3:
Novel in situ 4D (3D plus time) synchrotron X-ray tomography experiments using a reactive salt system have been carried out at the Swiss Light Source (Paul Scherrer Institute). In total ten experiments have been conducted with an overall data volume of more than 20 TB. The data is being analysed using advanced image analysis algorithms that allow the treatment of large correlative data sets. The nanoEARTH team is implementing mathematical microstructural descriptions developed in O1 to further analyse the evolution of the reaction-induced pore space and couple this to transfer machine-learning algorithms to predict porosity and permeability evolutions.
Work performed to address O4:
First theoretical steps towards combining molecular- and continuum-scale models have been taken, but this objective is part of the plan for 2023 and onwards.
• Development of a multi-scale analysis workflow to combine electron and X-ray microscopy of hydrothermally altered rocks with porosity ranging from a few nanometres to tens of microns.
• Development of a machine-learning approach coupled with statistical microstructural descriptors to analyse hydrothermally altered rocks and their multi-scale porosity (Amiri et al. 2022, EarthArXiv).
• Experiments on reaction-induced porosity and quantification of the pore space via in situ synchrotron X-ray tomography.
• First step to implement experimental observations of the transient behaviour of reaction-induced, multi-scale porosity into natural observations via transfer learning algorithms to estimate the permeability during natural reactive fluid-rock interactions.
• High-resolution transmission electron microscopy and statistical analysis of nanoporosity in serpentinites.
• Theoretical framework and molecular dynamics simulations to quantify the effect of nanoconfinement on the dielectric constant of water under natural conditions. Implementation of results into thermodynamic simulation packages to evaluate the impact on mineral solubility and fluid speciation.
• Theoretical framework to implement surface roughness into molecular dynamics simulations to probe the effect on fluid transport in natural nanopores.
• Electron microscopy measurement of paleo-stresses induced via fluid-driven mineral reactions and their effect on the generation of reaction-induced fractures, hence permeability enhancement (Plümper et al., 2022, Geology).
• Electron microscopy coupled to thermodynamic modelling to quantify the effect of grain-scale equilibrium reactions on reactive fluid flow (Zertani et al. 2022, CMP).
• Development of a machine-learning approach coupled with statistical microstructural descriptors to analyse hydrothermally altered rocks and their multi-scale porosity (Amiri et al. 2022, EarthArXiv).
• Experiments on reaction-induced porosity and quantification of the pore space via in situ synchrotron X-ray tomography.
• First step to implement experimental observations of the transient behaviour of reaction-induced, multi-scale porosity into natural observations via transfer learning algorithms to estimate the permeability during natural reactive fluid-rock interactions.
• High-resolution transmission electron microscopy and statistical analysis of nanoporosity in serpentinites.
• Theoretical framework and molecular dynamics simulations to quantify the effect of nanoconfinement on the dielectric constant of water under natural conditions. Implementation of results into thermodynamic simulation packages to evaluate the impact on mineral solubility and fluid speciation.
• Theoretical framework to implement surface roughness into molecular dynamics simulations to probe the effect on fluid transport in natural nanopores.
• Electron microscopy measurement of paleo-stresses induced via fluid-driven mineral reactions and their effect on the generation of reaction-induced fractures, hence permeability enhancement (Plümper et al., 2022, Geology).
• Electron microscopy coupled to thermodynamic modelling to quantify the effect of grain-scale equilibrium reactions on reactive fluid flow (Zertani et al. 2022, CMP).