Periodic Reporting for period 1 - GeoMos ( Development of a Method for the Exploration the Joint Geology-Geophysics Model-Space)
Berichtszeitraum: 2021-08-23 bis 2023-08-22
The Action titled "Development of a Method for the Exploration of the Joint Geology-Geophysics Model-Space" (GeoMos) aimed to develop modeling techniques that integrate geophysical data, such as gravity field anomalies, with geological measurements, such as the orientation of the contacts between rock units and their locations. This development was driven by the need to capture a snapshot of the range of models allowed by the data and the plausible features that the data can accurately resolve. Indeed, the necessity to quantitatively and reproducibly integrate geological and geophysical modeling has been recognized by the geoscientific community as an efficient means to reduce uncertainty in exploration, monitoring, and risk assessment related to natural resources and subsurface management.
In addition, given the current challenges in modeling increasingly complex areas, it has become necessary not only to produce a single 'best guess' model but a series of models representing a range of plausible scenarios to provide insights into the 'unknown unknowns', to reduce risks and plan future exploration efforts. To address this, this project introduced methods for the robust integration of geological and geophysical modeling through the development of a modeling algorithm capable of jointly considering geological and geophysical measurements. It relies on new techniques to generate collections of models that fit the data and represent different geological scenarios, using modeling algorithms:
1. For both geological and geophysical data, where geology and geophysics are linked by converting information from a geophysical model into inputs for geological modeling and vice versa.
2. By calculating series of intermediate models between differing scenarios that all fit the geophysical data with a similar level of fidelity.
3. By calculating a large number of models that fit the data within uncertainty using an automated process for the addition or removal of possibly unknown rock units to better explore the full range of possibilities.
These algorithms were initially tested with idealized data and successfully applied to real-world measurements in the Western Pyrenees (spanning France and Spain) and the Boulia region in Northeastern Australia (Queensland). This allowed for the generation of plausible models that deviate from commonly accepted interpretations, showcasing the new methods and contributing to discussions about the studied areas.
The results are to be made open source upon acceptance of the journal publication presenting the final version of the code developped during the project.
In addition, given the current challenges in modeling increasingly complex areas, it has become necessary not only to produce a single 'best guess' model but a series of models representing a range of plausible scenarios to provide insights into the 'unknown unknowns', to reduce risks and plan future exploration efforts. To address this, this project introduced methods for the robust integration of geological and geophysical modeling through the development of a modeling algorithm capable of jointly considering geological and geophysical measurements. It relies on new techniques to generate collections of models that fit the data and represent different geological scenarios, using modeling algorithms:
1. For both geological and geophysical data, where geology and geophysics are linked by converting information from a geophysical model into inputs for geological modeling and vice versa.
2. By calculating series of intermediate models between differing scenarios that all fit the geophysical data with a similar level of fidelity.
3. By calculating a large number of models that fit the data within uncertainty using an automated process for the addition or removal of possibly unknown rock units to better explore the full range of possibilities.
These algorithms were initially tested with idealized data and successfully applied to real-world measurements in the Western Pyrenees (spanning France and Spain) and the Boulia region in Northeastern Australia (Queensland). This allowed for the generation of plausible models that deviate from commonly accepted interpretations, showcasing the new methods and contributing to discussions about the studied areas.
The results are to be made open source upon acceptance of the journal publication presenting the final version of the code developped during the project.
Work involved the development of numerical methods for the transfer of information from geological modelling to geophysical modelling and vice versa have been investigated, focussing on the modelling of gravity anomalies. The proof of concept was shown using synthetic data and the method was applied through a field application case in the Western Pyrenees in a region sitting on the border between France and Spain.
This brought new insights about the composition and structure of the continental crust in the region, with the generation of several geological scenarios constituting end-members that depart from some commonly accepted interpretations, thereby alimenting the discussion about the composition and structure of the Western Pyrenees. The investigations comprised varying the length of the subducted crust, the removal and addition of geological features affecting the mantle and crust to test hypotheses. For this, a technique for the generation of series of models representing intermediate cases between selected scenarios while honouring the available data was successfully used.
Following this, a method automatically generating rock units or removing them from the model was used to explore the range of scenarios comprising the presence of unknown rock units.
It was applied to a mineral exploration scenario in North eastern Australia (Boulia region, Queensland), bringing valuable new information about potentially hidden rock units that may be useful for decision making and prospect evaluation. Specifically, results reveal the possible presence of up to two anomalously dense rock units concealed from direct observations by a layer of weathered rocks but which are sensed by geophysics.
Dissemination activities were varied. The Fellow presented project work at 6 conferences, 2 invited lectures, 2 invited participation in workshops, and 3 seminars at the host institution. Invitations to present work also include 3 external seminars offered to companies. The Fellow also facilitated a masterclass and co-facilitated a short course.
The results will be published through 3 open access peer-reviewed publications lead by the Fellow (one accepted by the end of the project, while the process is ongoing for the other two). Collaborations in relation to the project lead the Fellow to act as co-author for three manuscripts submitted for publication in open-access publications and others are in preparation. Computer scripts developed for this project will be made available upon publication of the corresponding journal publications.
This brought new insights about the composition and structure of the continental crust in the region, with the generation of several geological scenarios constituting end-members that depart from some commonly accepted interpretations, thereby alimenting the discussion about the composition and structure of the Western Pyrenees. The investigations comprised varying the length of the subducted crust, the removal and addition of geological features affecting the mantle and crust to test hypotheses. For this, a technique for the generation of series of models representing intermediate cases between selected scenarios while honouring the available data was successfully used.
Following this, a method automatically generating rock units or removing them from the model was used to explore the range of scenarios comprising the presence of unknown rock units.
It was applied to a mineral exploration scenario in North eastern Australia (Boulia region, Queensland), bringing valuable new information about potentially hidden rock units that may be useful for decision making and prospect evaluation. Specifically, results reveal the possible presence of up to two anomalously dense rock units concealed from direct observations by a layer of weathered rocks but which are sensed by geophysics.
Dissemination activities were varied. The Fellow presented project work at 6 conferences, 2 invited lectures, 2 invited participation in workshops, and 3 seminars at the host institution. Invitations to present work also include 3 external seminars offered to companies. The Fellow also facilitated a masterclass and co-facilitated a short course.
The results will be published through 3 open access peer-reviewed publications lead by the Fellow (one accepted by the end of the project, while the process is ongoing for the other two). Collaborations in relation to the project lead the Fellow to act as co-author for three manuscripts submitted for publication in open-access publications and others are in preparation. Computer scripts developed for this project will be made available upon publication of the corresponding journal publications.
This project has extended a method for the modelisation of the geometry of rock units at depth using gravity data by integrating it with a geological modelling engine to reconcile geophysics and geology and to produce better constrained, more realiable and easily interpretable models.
The project has also applied to a real 3D case study a recent method for the navigation of the space of feasible models to generate series of models that are intermediate between specifically designed scenarios.
In addition, the project has introduced a 3D gravity modelling method where the number of rock units, their geometry and their density evolve during the process, building on previous work on trans-dimensional modelling. The proposed method allows sampling the range of plausible models including 'unknown unknowns' in terms of the number of rock units, their geometry and density that can be reasonably expected to honour the gravity data.
Results brought new insights into the state and composition of the continental crust around the Pyrenees mountain range, questioning established hypotheses about the structure of the subsurface and the density of rocks in a region of the Western Pyrenees. This also has potential implications for native hydrogen prospectivity and future exploration programs
The application of the proposed methods in the Boulia region (Northeastern, Australia) demonstrates the effectiveness of the method in deducing the possible presence of rock units concealed by a cover of weathered rocks with the generation of a large number of models with varying numbers of rock units and densities that honour the data. In this case, the proposed algorithms suggests that a family of scenarios consisting of the insertion of two anomalously dense rock units in the original model together with its deformation may be the most effective way to model the area. This application case shows the potential of the method to infer the presence of rock units hidden from direct measurements and support informed decision making in challenging subsurface scenarios.
The project has also applied to a real 3D case study a recent method for the navigation of the space of feasible models to generate series of models that are intermediate between specifically designed scenarios.
In addition, the project has introduced a 3D gravity modelling method where the number of rock units, their geometry and their density evolve during the process, building on previous work on trans-dimensional modelling. The proposed method allows sampling the range of plausible models including 'unknown unknowns' in terms of the number of rock units, their geometry and density that can be reasonably expected to honour the gravity data.
Results brought new insights into the state and composition of the continental crust around the Pyrenees mountain range, questioning established hypotheses about the structure of the subsurface and the density of rocks in a region of the Western Pyrenees. This also has potential implications for native hydrogen prospectivity and future exploration programs
The application of the proposed methods in the Boulia region (Northeastern, Australia) demonstrates the effectiveness of the method in deducing the possible presence of rock units concealed by a cover of weathered rocks with the generation of a large number of models with varying numbers of rock units and densities that honour the data. In this case, the proposed algorithms suggests that a family of scenarios consisting of the insertion of two anomalously dense rock units in the original model together with its deformation may be the most effective way to model the area. This application case shows the potential of the method to infer the presence of rock units hidden from direct measurements and support informed decision making in challenging subsurface scenarios.