Natural hydrogen (H2) is emerging as a promising carbon-free energy source, aligning with France’s ambition for carbon neutrality and energy sovereignty by 2050. Yet, its occurrence, distribution and long-term sustainability remain largely unexplored. In this context, the H2 and helium exploration company 45-8 Energy was granted the “Grand Rieu” exploration license in the northwestern Pyrenees (SW France), to further investigate its natural H2 system prospectivity, with the objective of drilling an exploration well in the near future.

The license covers part of the Mauleon Basin (North-Pyrenean Zone), a Cretaceous hyperextended rift basin inverted during the Tertiary Pyrenean orogeny (e.g. Saspiturry et al., 2020). This region and the adjacent Pyrenean foreland (Arzacq basin) to the north benefit from extensive historical datasets acquired since the 1950s by major academic research programs (e.g. Orogen project) and the Oil & Gas industry (e.g. historical Lacq and Meillon gas fields), including deep exploration wells, 2D/3D seismic reflection surveys and gravimetric and magnetic data.

Our current work aims to integrate and interpret these datasets to characterize each element of the H2 system and perform volumetric and risking evaluations of H2 prospectivity within the Grand Rieu license. Geophysical studies (e.g. Wang et al., 2016; Wehr et al., 2018; Lehujeur et al., 2021; Saspiturry et al., 2024) highlighted gravimetric, magnetic and velocity anomalies suggesting the existence of a large mantle body at depth (8-10 km) under ideal P-T conditions for serpentinization and H2 generation. Numerous active H2 seepages measured at the surface along the North Pyrenean Frontal Thrust system (Lefeuvre et al., 2022) suggest active serpentinization at depth and preferential migration pathways along regional faults. Proven Upper Jurassic and Lower Cretaceous carbonate reservoirs with overlying effective seals are well-known northward in the Pyrenean foreland (Lacq and Meillon gas plays). However, their presence and properties in the Mauleon Basin remain historically poorly studied and therefore needed to be further characterized to improve their predictability. Ongoing seismic interpretation, aiming to identify potential traps and H2 migration pathways at regional scale, reveals a complex structural framework directly linked to Cretaceous hyperextension and following Cenozoic Pyrenean compression. Preliminary results suggest the existence of deep-seated structures suitable for H2 accumulation.

Overall, the Mauleon Basin appears to offer a unique geological setting favorable for natural H2 generation, migration and accumulation. Further characterization of these processes through dynamic numerical modelling is necessary to better constrain the natural H2 system. In addition, volumetric and risking evaluations will guide the selection of a drilling target within the Grand Rieu license, marking a critical step toward assessing the viability of natural hydrogen as a sustainable energy resource in France’s energy transition.

How to cite: Laurent, A., Boka-Mene, M., De Boisgrollier, T., Fontanelli, L., Potel, S., and Hauville, B.: Exploring natural hydrogen in the NW Pyrenees (France), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18410, https://doi.org/10.5194/egusphere-egu26-18410, 2026.

Unlike traditional hydrocarbon and mineral exploration, where decades of empirical data informed threshold values, natural hydrogen exploration requires establishing new baselines for what constitutes an economically significant anomaly. To use soil gas measurements as an effective tool in the geological hydrogen research and exploration we must understand the limitations of the existing instruments, what are background hydrogen values in soil and what other data are required for the reliable interpretation of the soil gas measurements and monitoring data sets.
 Current technology constraints remain a significant challenge in natural hydrogen soil gas sensing. Field-appropriate commercially available sensors exhibit combinations of limited operating ranges, cross-sensitivity to humidity and other gases, baseline drift over time and exposure, and hysteretic dynamics. CSIRO has developed Seeptracker multi-gas (hydrogen, methane, carbon monoxide and carbon dioxide) monitoring device. In this presentation we want to share findings regarding the commercially available hydrogen sensing components comprising Seeptracker and results of deploying this instrument around the world to collect soil gas data in various geological settings. Seeptracker utilises multiple commercially available sensors to measure hydrogen and other gases and the output is enhanced by an extensive calibration routine to improve gas measurement accuracy. Developing Seeptracker revealed the challenge of balancing sensing quality, deployment compatibility, and cost/effort scaling. To achieve suitable long-term large-scale autonomous field deployment requires a clearly and concisely defined study scope, together with a well-characterised sensor package and robust calibration routine to address the multi-variate challenge. 
 Interpreting multi-gas measurements introduces both opportunities and risks for false positives. Effective interpretation of soil gas data for geological hydrogen research requires integration with multiple complementary datasets. Geological mapping identifying serpentinisation fronts, radiolytic source rocks, or fault systems provides essential structural context. Geophysical surveys, particularly magnetotellurics and gravity, can delineate subsurface fluid pathways and potential trap geometries. Geochemical analysis of associated gases, including methane, helium, nitrogen, carbon and noble gas isotopes, potentially enables source discrimination and migration pathway delineation. 
Our work with Seeptracker deployments across diverse geological settings around the world suggests that sustained hydrogen concentrations in soil gas can be used as an effective tool for natural hydrogen exploration, but it cannot be used in isolation. The detailed follow-up investigation is required, particularly when accompanied by spatial coherence and temporal stability and crucially ensuring that measured natural hydrogen is geological. Our studies demonstrate that continuous monitoring data capturing temporal variability, rather than single-point measurements, enhances interpretation confidence. In this presentation we show the performance of the current hydrogen sensors within the CSIRO multi-gas monitoring system Seeptracker, including limitations, and present soil gas monitoring results from various sites around the world. We also show in greater detail soil gas studies from Australia, and the interpretation of the soil gas monitoring results is constrained by geochemical, geophysical and isotope data sets.

How to cite: Markov, J., Mow, V., Kasperczyk, D., Breedon, M., Moran, M., Down, D., Camilleri, M., Strand, J., and Liang, J.: Establishing meaningful soil gas measurements for geological hydrogen research and exploration, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18056, https://doi.org/10.5194/egusphere-egu26-18056, 2026.

Natural hydrogen gas (H₂) generated through the serpentinization of mantle rocks is a promising source of clean energy. For large-scale serpentinization and natural H₂ generation to occur, the mantle rocks need to be brought into a optimal temperature range (the serpentinization window) and into contact with water. Alpine-style rift-inversion orogens, formed during the closure of rift basins, provide excellent environments for serpentinization-related natural H₂ generation, while also harbouring extensive volumes of sediments in which natural H₂ accumulation could form. In such orogens, erosion is known to have an important impact on exhumation processes and sediment distribution, but to what degree erosion efficiency influences natural H₂ resource potential remains poorly understood. We use numerical geodynamic models of rift-inversion to explore and, importantly, quantify the relative roles of erosion and tectonic processes by applying different erosion efficiencies and initial rift phase durations.

Our modelling shows that, regardless of erosion efficiency, initial rift duration is a dominant factor during both the extension and inversion phase. Prolonged rifting causes increased mantle exhumation and thus higher natural H₂ generation potential. Erosion efficiency exerts only a secondary effect, in that more efficient erosion modestly reduces H₂ generation potential by narrowing the serpentinization window. Inversion of advanced rift basins results in asymmetric orogens in which mantle material is incorporated into the overriding wedge, a configuration that is critical for generating high natural H₂ generation potential in these systems. Nevertheless, efficient erosion of otherwise symmetric orogens formed after limited rifting allows for a shift to an asymmetric style, with significant mantle exhumation and natural H₂ generation potential.

However, efficient erosion and associated fast exhumation of relatively hot material in orogens can also decrease the vertical extent of the serpentinization window, reducing natural H₂ generation potential. Moreover, rapid erosion can remove the otherwise abundant potential reservoir rocks and seals needed for exploitable natural H₂ accumulations to form. Still, these negative effects of erosion on “conventional” natural H₂ resources (involving H₂ accumulation in reservoir rocks), may be favourable for “unconventional” natural H₂ resources. Systems with relatively hot mantle material close to the surface may in fact be suitable for stimulated natural H₂ exploitation efforts, involving direct drilling of the mantle source rock itself.

Thus, although erosion efficiency is not the dominant factor, it can still have a considerable impact on natural H₂ potential in rift-inversion orogens. Therefore, a thorough understanding of the evolution of those orogens targeted for exploration, will be of great importance. This challenge can be aided by numerical geodynamic models such as those presented here, with which we perform a first-order analysis of natural examples from the Pyrenees, Alps, and Betics.

How to cite: Zwaan, F., Glerum, A. C., Brune, S., Vasey, D. A., Naliboff, J. B., Manatschal, G., and Gaucher, E. C.: The impact of erosion processes on natural H2 resource potential in Alpine-style orogens, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8255, https://doi.org/10.5194/egusphere-egu26-8255, 2026.

The Engadine valley, located in the Grischun area in SE Switzerland, presents multiple mineralized springs distributed along the Engadine fault. Hydrogen (H₂) concentration measured along the Engadine fault can reach up to 1900 ppm, indicating the presence of both, a deep groundwater flow system and a deep-seated 'kitchen'. These observations suggest that the Engadine fault may control the regional hydrodynamics and likely also the hydrogen production along the Engadine valley. A key factor to identify and understand the location of the H₂ kitchen, fluid pathways and related water in- and H₂ out-flow is the understanding of the nappe stack in the Grischun area and its relation to the Engadine fault. The latter, represents a major SW-NE striking >100km long structure that resulted from post-collisional oblique strike-slip movements during Oligocene-Miocene time. It transects the Late Cretaceous Austroalpine nappe stack, floored by the Pennine, ultramafic rocks bearing ophiolites, inherited from the closure of the Alpine Tethys proto-oceanic domain. Thus, a key question is whether there is a hydrodynamic link between the ultramafic source rocks flooring the rift-inversion nappe stack, the Engadine fault, acting as a possible conduit for deep water circulation, and the occurrence of springs and H₂ anomalies in the soil gas. To answer to this question, we constructed a numerical hydrodynamic model of the Engadine and surrounding area, including the Engadine fault. This model allows us to carry out regional-scale simulations to investigate the interplay between topography and a deep, permeable conduit (e.g. Engadine fault) and its control on hydrothermal circulation. The model couples groundwater flow, heat transport and solute transport, and will be calibrated with surface observations (location of springs and chemical anomalies in water and soil gas). First results suggest that fluid upwelling occurs SW of St.Moritz and NE of Scuol along the Engadine valley, whereas the fault-segment between St.Moritz and Scuol corresponds to a region of meteoric recharge. This SW-NE distribution of deep upwelling correlates well with first geochemical field measurements. Future work will include chemical fluid-rock interaction to fully understand the hydro-chemical conditions of H₂ formation and H₂ pathways to the surface along the Engadine valley. Ultimately, this well-constrained, regional scale model, will serve as an exploration tool, allowing us to quantitatively evaluate the potential for energy-related exploitation (H₂ and/or geothermal).

How to cite: Gasser, Q., Manatschal, G., Alt-Epping, P., Gaucher, E. C., Pierre, S., Dimasi, F., and Ulrich, M.: The link between deep groundwater flow and serpentinization-sourced H2 production in rift inversion orogens: the example of the Engadine valley (SE Switzerland), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10381, https://doi.org/10.5194/egusphere-egu26-10381, 2026.

Ophiolitic succession of the Eastern Mediterranean region includes one of the most famous natural H₂ leakage spot, globally known as “Chimera Gas Seepage”, noted since ancient times. Geochemical analysis on the seepage revealed that the origin of the gas is abiotic and along CH₄, %10-12 of H₂ is associated with the seepage due to the serpentinisation process which is widely accepted as one of the main mechanisms for the natural H₂ generation.

Radiolysis, considered as another natural H₂ generation process, is defined as the decomposition of H₂O by decay of ²³²Th-²³⁸U-⁴⁰K causing an increase in radioactivity levels. Therefore, increasing radioactivity levels can be detected to identify potential natural H₂ generating zones by calculating the radiogenic heat generation. This study aims to test this hypothesis by implementing the usually neglected or overlooked ²³²Th-²³⁸U-⁴⁰K concentration measurements, also known as SGR logs. A-1 well drilled in the onshore portion of the Antalya Bay, SW Turkey, includes ²³²Th-²³⁸U-⁴⁰K concentration measurements covering an allochthonous ophiolitic section. Penetration into the ophiolites by a well, proximity of well location to the Cirali gas seepage (60 km NE of the seepage) and 2D seismic sections acquired in the region make the study area a perfect spot to test the applicability of integrated methods for natural H₂ exploration.

The most significant finding along the ophiolitic section of the A-1 well is the presence of a peak in radiogenic heat generation that might indicate a potential natural H₂ generation zone. On the other hand, thermal models derived from the interval velocities of 2D seismic survey nearby indicate that vast majority of generated H₂ by serpentinisation process must have migrated from the deepest sections of the ophiolites as temperatures are generally quite low in the area. Apart from that, thermal models also demonstrate the presence of temperature anomalies exhibiting themselves as rapid lateral increases in temperatures that can be associated with the fluids in the sedimentary succession.

As a conclusion, this study provides a unique workflow to reveal potential natural H₂ generating zones that can be applied all along the wells if ²³²Th-²³⁸U-⁴⁰K concentration measurements cover zone of interest not only in the Eastern Mediterranean but for any region. In terms of play fairway, 2 play types have been identified. Naturally generated H₂ can accumulate both in the serpentinites as it is already proven by Chimera gas seepage, or it can migrate into Plio-Miocene aged reservoirs in the area. In terms of expulsion mechanism, heavy deformation and compressional tectonic phase controlled by ongoing convergence of African and Anatolian plates create faults and fracture zones that might allow migration of natural H₂ from the deeper sections into the shallower structures. However, detailed geomechanical analysis should be performed to understand and prevent potential seal breach risks. The methodologies provided by this study might unlock the path to a potential natural H₂ discovery that can turn the Eastern Mediterranean region into a unique natural H₂ exploration theatre.

How to cite: Uyanik, A.: Highlighting Natural H2 Generation Potential of the Eastern Mediterranean Ophiolites by Implementing 232Th-238U-40K Concentration Measurements and Thermal Modeling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-758, https://doi.org/10.5194/egusphere-egu26-758, 2026.

Helium is a critical raw material for medical, industrial, and scientific applications, yet its global supply is largely dependent on hydrocarbon production, linking helium availability to CO₂ emissions and geopolitical constraints. This dependency has driven growing interest in alternative, low-carbon helium sources, particularly radiogenic helium systems associated with N₂-rich and CO₂-poor geological fluids. However, the geological controls on helium generation, migration, and accumulation in such non-hydrocarbon systems remain poorly constrained.

Radiogenic helium systems require the combination of a U–Th-enriched crystalline basement generating helium through alpha decay, sufficient heat to liberate helium from mineral hosts, and fault- and fracture-controlled pathways enabling upward migration while limiting diffusive loss. Where suitable reservoir and seal configurations exist, migrating helium may locally accumulate. Continental rift and geothermal provinces seem especially favourable for these conditions due to elevated heat flow, crustal thinning, and dense fault networks.

In this study, we first compile helium data from the literature to produce a Europe-wide map linking helium occurrence to rifts, sedimentary basins, and Variscan basement exposures, providing a european framework for helium exploration. New helium concentration data from thermal fluids in the Upper Rhine Graben are used to assess the spatial distribution of helium fluxes and their relationship with fault architecture. While near-surface degassing limits shallow accumulation, major fault systems emerge as first-order controls on helium transport. Their deeper continuations beneath sedimentary basins represent promising exploration targets where appropriate reservoir–seal configurations may allow helium retention. This study provides a preliminary framework to guide exploration of helium in European rift and geothermal settings.

How to cite: Wallentin, A., Murray, J., Truche, L., and Lemarchand, D.: Exploring Helium in European Rifts: New Insights from the Upper Rhine Graben, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2992, https://doi.org/10.5194/egusphere-egu26-2992, 2026.

Reliable subsurface temperature models are a key prerequisite for geothermal exploration, reservoir assessment, and broader subsurface energy applications. Within the GeoChaNce research project, we present an integrated geological and thermal characterization of the Bavarian part of the North Alpine Foreland Basin (NAFB), combining petrophysical analyses of a large heterogeneous well dataset with advanced geostatistical modelling approaches.

The thermal analysis focuses on developing a fully volumetric 3D temperature model that covers depths ranging from 300 m to 5000 m true vertical depth. The temperature dataset comprises 196 bottom-hole temperature (BHT) values, which were corrected using Monte Carlo methods to account for uncertainty, and 19 high-quality continuous temperature logs, including wireline and fiber-optic measurements. To robustly account for data heterogeneity and measurement uncertainty, particularly in the error-prone BHT correction methods, Empirical Bayesian Kriging (EBK) was applied within a 3D framework. The model was computed on a 100 × 100 × 100 m voxel grid and provides probabilistic temperature distributions for P10, P50, and P90 scenarios. Cross-validation using a leave-one-out approach yields a mean standard error of 5.6 K, with more than 87% of predictions falling within the modelled 90% confidence interval.

The resulting temperature model reproduces well-known regional thermal anomalies of the Molasse Basin, including positive anomalies in the Munich and Landshut areas and a pronounced negative anomaly associated with the Wasserburg Trough. In addition, a 3D Empirical Bayesian Indicator Kriging approach was used to derive probability maps for reaching specific temperature thresholds (e.g., 80 °C and 100 °C), providing a robust probabilistic framework for geothermal assessment.

Ongoing work focuses on coupling the solely statistical EBK temperature model with lithology-specific thermal conductivity data derived from laboratory measurements, mixing-law models, and petrophysical interpretations of logging data. This will allow calibration of the temperature field, derivation of regional heat-flow densities, and calculation of horizon-based temperature gradients. The GeoChaNce results provide an improved, uncertainty-aware thermal framework for the Bavarian Molasse Basin, contributing to more reliable geothermal resource assessments and forming a key component for a future geothermal decision-support system for the reservoir.

How to cite: Schölderle, F. and Zosseder, K.: From Heterogeneous Well Data to Probabilistic 3D Temperature Modelling of the Bavarian Molasse Basin for Geothermal Exploration, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13093, https://doi.org/10.5194/egusphere-egu26-13093, 2026.

The Upper Jurassic to Lower Cretaceous (Purbeck) sedimentary succession of the South German Molasse Basin, here referred as the Malm Reservoir, hosts one of the largest hydrothermal resources in continental Europe. It exhibits strong heterogeneity driven by depositional facies variability within a sequence stratigraphic framework, diagenetic overprint including karst horizon development, and structural elements typical for foreland sedimentary basins. The GIGA-M project aims to study the deep geothermal reservoir of the greater Munich area through integrated well data and large-scale 3D seismic interpretation, providing the geological basis for a reservoir management model enabling synergetic geothermal utilisation. Hydraulically active zones in the most productive geothermal wells are commonly observed within karstified intervals (Hörbrand et al., 2025, Schölderle et al., 2023) and are therefore commonly described as one of the main reasons for the exceptional productivity of the reservoir. Facies architecture and Mesozoic to Cenozoic faults further influence reservoir heterogeneity and fluid flow. Karst horizons are unevenly distributed throughout the reservoir, indicating a complex interplay of syn-depositional and diagenetic controls that is common in many karstified carbonate reservoirs worldwide.

This study evaluates how sequence stratigraphy, facies architecture, and karst development control flow zones and matrix porosity in the Malm Reservoir. The analysis focuses on stratigraphic and facies organisation and karst characterisation. Available well data and recent studies indicate that fault systems and fractures play only a minor role in the hydraulic behaviour of the Malm Reservoir; consequently, they are not a primary focus of this study. Our workflow integrates geophysical well logs, mud-log descriptions, and borehole image logs to identify and classify karst features in wells and, where flow data are available, to correlate karst categories with observed flow zones. This approach enables the recognition of karst horizons associated with enhanced porosity and permeability, directly relevant to reservoir quality and well-interference assessment.

A regional sequence stratigraphic framework (Wolpert et al, 2022; Wolpert, 2020) is used to link relative sea-level changes to facies distribution within the carbonate ramp system. Facies associations primarily control matrix porosity and storage properties, whereas sequence boundaries mark exposure surfaces and sedimentary gaps where karst can develop. While early diagenetic karst may initiate at sequence boundaries, the most extensive karst development is interpreted to result from prolonged subaerial exposure of the reservoir during the Cretaceous, highlighting the critical importance of identifying and differentiating sequence boundaries according to their timing and duration of exposure. This Cretaceous karst generation is considered the main candidate for the laterally extensive karst systems that cross-cut facies boundaries and form the main geothermal flow zones, as confirmed by flow observations in wells. These karst horizons exert a first-order control on transmissivity and hydraulic connectivity. Within the GIGA-M project, this stratigraphic and karst framework provides the geological basis for developing facies- and karst-probability maps calibrated with existing and future GIGA-M 3D seismic data, enabling the assessment of flow connectivity and well interference and supporting geothermal reservoir management at the greater Munich area scale.

How to cite: Crinière, A., Ernst, V., Beichel, K., Bendias, D., Bamberg, B., Schölderle, F., Nasralla, M., Pfrang, D., Banerjee, I., and Zosseder, K.: Sequence-stratigraphic control on facies and karst in Europe’s largest geothermal carbonate reservoir: The Malm Reservoir of the South German Molasse Basin (greater Munich area), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18135, https://doi.org/10.5194/egusphere-egu26-18135, 2026.

Young igneous geothermal systems recharge by magmatic activity. Due to Iceland’s location on the mid-ocean ridge, repeated dyking compensates here for the spreading. This study examines the impact of intrusive and eruptive events on the thermal evolution of the Krafla geothermal system. The so-called “Krafla fires” in 1975-84 were a volcanic episode comprising 20 intrusive and eruptive events, during which seven of them intersected the geothermal system.

The effects of repeated dyking on temperature, pressure, and enthalpy, as well as steam content, are modelled in simple 2D profiles with HYDROTHERM (USGS). Calculating a heat budget can help to exploit geothermal energy sustainably: How much energy is inputted by the dykes into the geothermal system? How much of this heat is lost to the atmosphere by advection and conduction? How fast is heat transferred in the subsurface?

The total heat input of the dyke into the geothermal system is 0.5-1 x 10¹⁸ J. During, and shortly after the eruptive episode, the dyke nearly cools down to the ambient temperatures of the system. Models and previous analyses of steam clouds in air photos indicate that around 10 % of the heat is lost from the surface to the atmosphere, mostly in the first weeks/months after the dyking event, while 90 % of the dyke’s energy is dissipated into the geothermal reservoir. As the system is already close to the boiling point, the additional heat input by the dyke, leads to steam generation, which rises in the high-permeable lava-hyaloclastite layer. It collects below the clay cap and rises through fissures and fractures. In the lower permeable layer of basement intrusions, the steam is less mobile and stays in the vicinity of the dyke. The main changes in temperature and pressure can be observed in the two-phase and superheated steam regions, where enthalpy increases strongly compared to the initial setting. Long-term simulations indicate that the heat input by the dykes formed in the Krafla fires remains in the reservoir for at least several decades and plays a critical role in maintaining the geothermal system.

How to cite: Fehrentz, P., Gudmundsson, M. T., and Reynolds, H. I.: Thermal effects of intrusive events on geothermal systems: Heat transfer modelling during (and after) the Krafla volcano-tectonic episode 1975-84, NE-Iceland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18250, https://doi.org/10.5194/egusphere-egu26-18250, 2026.

Global copper demand is projected to increase from 22.8 Mt in 2024 to 35 Mt by 2040, driven largely by the transition to green energy technologies. Existing and announced Cu mining projects are forecast to meet only 70% of this demand by 2035, creating a significant supply deficit. Mining of subvolcanic magmatic brines - hypersaline and potentially supercritical fluids enriched in metals – has been proposed as an alternative source (Blundy et al., 2021). Here, we assess the potential mass of Copper Initially in Place (CIIP) in such reservoirs.

Based on published resistivity models from 46 active magmatic-hydrothermal systems, we estimate the typical volume of brine reservoirs to range from 10 to 200 km³ and the average top reservoir depth to be 1.7 km, well within reach of modern drilling technology. Typical reservoir porosity in the shallow sub-critical zone is 8±6% and decreases to 3±3% in the deeper supercritical zone. Copper concentration in the brines is the most uncertain property.  Data from fluid inclusions and Cu solubility modelling suggest that most brine reservoirs will host modest Cu concentration (ca. 10’s to 100’s ppm), but values could exceed 10,000 ppm in the most Cu enriched systems.

We combine these estimates of reservoir volume, porosity and copper concentration using a probabilistic Monte Carlo framework to provide estimates of CIIP. Our analysis indicates a lognormal CIIP distribution with a median (P50) of 8.6 Mt and a P90 of 55 Mt, suggesting that individual magmatic brine resources may be comparable in size to conventional copper porphyry deposits. Moreover, a single high-flow-rate well tapping into a supercritical reservoir could produce approximately 2.4 kt of copper per year. A large-scale operation comprising multiple wells could yield 0.24 Mt/year, equivalent to roughly 1% of current global demand.

A Cu brine mine could extract geothermal energy from the produced fluids. We envisage a self-powered Cu brine mine, with net positive energy per kg of Cu and a minimal environmental footprint. While significant challenges remain regarding exploration for copper-rich brine reservoirs and production of very hot and possibly supercritical brines, brine mining offers a potentially significant source of Cu that could be produced with much lower energy demand and negative environmental impact than conventional mining.

Blundy, J., et al. "The economic potential of metalliferous sub-volcanic brines." Royal Society Open Science 8.6 (2021): 202192.

How to cite: Paulatto, M., Jackson, M., Hu, H., Berry, A., Crisp, L., Beckie, R., and Pacey, A.: Assessing potential ‘copper in place’ in subvolcanic brines, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10130, https://doi.org/10.5194/egusphere-egu26-10130, 2026.