Orals: Fri, 2 May | Room K1
Understanding the dynamic processes within volcanic systems is crucial for advancing igneous petrology and mitigating volcanic hazards. Traditional imaging techniques often fall short in capturing the real-time, three-dimensional transformations occurring in volcanic materials under varying conditions. We present various studies from ESRF users employing static scans or in situ 4D (three spatial dimensions plus time) synchrotron-based X-ray microtomography to observe and quantify natural and synthetic magma's kinetics and morphological evolution under controlled thermal and pressure conditions.
Static scans of volcanic slags or volcanic bombs capture intricate frozen microstructural evidence of conduit processes such as magma ascent, expansion, and cooling with the preservation of features such as elongated vesicles and crystal clots that shed light on the interplay between degassing and crystallisation in dynamic volcanic systems.
Even minimal volumes of bubbles or crystals can significantly affect magma viscosity, potentially influencing eruptive dynamics. Utilising the high flux and coherence of synchrotron radiation, we achieved temporal and spatial resolutions sufficient to monitor rapid nucleation and growth of bubbles and microlites within the melt.
Integrating 4D synchrotron imaging with advanced analytical tools such as digital volume correlation and dynamic segmentation offers insights into the microstructural evolution of volcanic materials. This approach provides valuable data for modelling and predicting volcanic activity. Our results underscore the potential of cutting-edge imaging technologies in unravelling the complexities of igneous petrology, contributing to the broader field of Earth sciences.
How to cite: Cordonnier, B.: Unleashing Volcanic Fury or Just a Snooze? Freezing Magmatic Processes in Motion with 4D Synchrotron Imaging, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12610, https://doi.org/10.5194/egusphere-egu25-12610, 2025.
X-ray nano-computed tomography (nano-CT) is an established method to obtain 3D spatial image information in static systems. This method has enabled researchers to access ever finer details of complex bulk structures in various fields. Within Eath Science, this is relevant for the study of nanoporous formations, such as chalk, revealing the pore network structures from which local petrophysical formation properties can be derived. Various dynamic processes are also occurring, or are dependent on features at, the nanoscale, like residual CO2 trapping. Besides X-ray attenuation differences, phase contrast is another acquisition mode that allows for resolving different phases within the bulk. Imaging is limited by sample and feature size, time, as well as sample composition and stability. Today, high brilliance synchrotron X-ray sources allow for true nanometer resolution and acquisition times of minutes, rather than hours. Furthermore, recent advances in working at higher X-ray energies put imaging of X-ray sensitive aqueous systems within reach, without sample deterioration. We will illustrate the capacity of nano-CT on an example of static chalk data for deriving various formation properties. We will then give an overview of instrumental approaches for doing synchrotron nano-CT, experimental limitations, requirements, and illustrate how time resolved imaging (4D) of dynamic geological processes may be accomplished in the near future.
How to cite: Schiefler, A. A., Osholm Sørensen, H., Nikitin, V., and Mokso, R.: X-ray nano-CT: A road towards 4D nanoscale data in Earth Science, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18010, https://doi.org/10.5194/egusphere-egu25-18010, 2025.
Nano-imaging is a critical tool for understanding the intricate chemical, physical, and structural characteristics of Earth materials, offering different perspectives on processes such as mineral formation, melt dynamics, and element redistribution. In this context, ID16B at the European Synchrotron Radiation Facility (ESRF) stands out as a premier beamline for high-resolution nano-imaging, combining cutting-edge technology with versatility for studying diverse complex geological phenomena.
The ID16B beamline is specifically designed for nano-focused X-ray imaging and spectroscopy, delivering exceptional spatial resolution and sensitivity. Its advanced technical capabilities include hard X-ray nano-tomography with a pixel size as small as 25 nm, nano-X-ray fluorescence utilizing a sub-100 nm pencil beam capable of detecting element concentrations down to the parts-per-million (ppm) level, nano-X-ray diffraction with a monochromatic beam of ΔE/E ≈10-4, and nano-X-ray absorption spectroscopy covering an energy range of 5 keV to 33 keV with a resolution of 0.5 eV. This energy range encompasses the K-edges and L-edges of numerous elements, allowing comprehensive elemental and chemical analysis.
A particularly unique feature of ID16B is its capability for in situ x-ray tomography imaging at elevated temperatures using a custom-designed furnace. The furnace enables experiments to be conducted at temperatures up to 1000°C, offering an opportunity to simulate geological conditions and directly observe dynamic processes such as crystallization and phase transitions. Additionally, the high-flux synchrotron source at ESRF enables rapid data acquisition, allowing complete tomography scans to be performed within seconds. This capability makes it an exceptional platform for investigating dynamic and time-sensitive geological processes.
The ID16B beamline's technical innovations and experimental flexibility highlight its critical role in nano-imaging within Earth Sciences. Its combination of imaging techniques allows researchers to obtain detailed compositional and structural data without damaging valuable geological samples. By providing access to nano-scale measurements through various complementary techniques, ID16B empowers researchers to explore geological processes with unprecedented detail and accuracy, addressing long-standing questions and opening new avenues for interdisciplinary investigation
How to cite: Pinzon, G. and Villanova, J.: ID16B Beamline at ESRF: Multi-dimensional Nano-imaging in Earth Sciences, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8437, https://doi.org/10.5194/egusphere-egu25-8437, 2025.
Characterizing accurately rock properties at the core scale is essential for effective reservoir scale modelling. In particular, in carbonate rocks posing unique challenges due to their inherent heterogeneities across multiple scales. While standard core analysis methods provide precise laboratory measurements, in many cases they fail capturing pore-scale variability within core plug samples. Digital rock physics (DRP) has emerged, in the last decades, as a powerful method addressing this gap, utilizing X-ray computed tomography (CT), micro-CT, and numerical simulations to analyse rock properties. DRP has been used widely to estimate rock properties such as porosity, permeability, and elastic moduli in carbonate and siliciclastic rocks. Nevertheless, there remains no standardized workflow for numerically characterizing rock properties in carbonates.
This study proposes three innovative applications leveraging computer vision and machine learning methods. The first application focuses on analyzing X-ray CT data to classify core sample textures. By modeling CT data, extracting representative textural descriptors, and employing the Kohonen method—an unsupervised classification technique—this approach identifies and categorizes primary textures within core sample images. The second application aims to interpolate rock properties obtained from core plug laboratory measurements along core samples. This approach exploits the continuity of properties like porosity and density observed in three-dimensional X-ray CT images by using a Convolutional Neural Network (CNN) system to interpolate these properties along the cores.
The third application introduces a novel multiscale method for simulating permeability and porosity in heterogeneous carbonate samples using 3D X-ray CT images. This approach uniquely incorporates a quantitative description of heterogeneity through machine learning-based texture classification. The texture classification results are then applied to scale up simulations of rock properties from fine to coarse scales. Finally, the proposed methods are demonstrated using two carbonate samples from a Middle East carbonate oilfield reservoir.
How to cite: Jouini, M. and Al-Khalayaleh, N.: Machine Learning and Digital Rock Physics Approaches for Multiscale Characterization of Rock Properties, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1564, https://doi.org/10.5194/egusphere-egu25-1564, 2025.
Periods of volcanic unrest present significant challenges for emergency management due to the inherent uncertainties. Rapid and unpredictable changes in the system conditions can signal either the onset of eruptive activity or a transition back to a quiescent state following non-eruptive unrest. In dormant volcanoes, such unrest is often driven by important variations in the hydrothermal system. Even in the absence of magma ascent or eruption, these variations can lead to hazardous phenomena, including phreatic eruptions caused by the rapid heating and vaporisation of fluids at shallow depths or landslides resulting from the failure of altered pyroclastic units.
Vulcano Island, an open-conduit system during the Middle and Modern Ages, currently represents a closed-conduit volcano with significant volcanic risk due to its potential for renewal of eruptive activity and associated hazards. This risk becomes particularly high during the summer, when tourism is at its peak. In fall 2021, Vulcano experienced one of the most significant episodes of unrest at La Fossa Crater in decades, marking a potential progression towards an eruption. Observations in September showed an increase in monitored parameters such as fumarole temperatures, steam emissions and concentrations of acid gases such as CO₂ and SO₂ as well as seismicity and uplift. In response, the Italian Civil Protection raised the alert level for Vulcano from green to yellow on 1 October. This phase of unrest ended in December 2023.
This escalation has prompted new research to deepen our understanding of the volcano's hydrothermal system and its dynamic behaviour, shedding light on the potential causes of phreatic and phreatomagmatic unrest phases. We present a comprehensive dataset on the microstructural characteristics of Vulcano's rocks, including pore content and size distribution, hydraulic and elastic properties, and mechanical behaviour. Volcanic samples were collected from various outcrops on Vulcano island, assuming they could represent the rock sequence down to approximately 1000 metres, through the correlation with the “horizons” identified along two cores extracted from the geothermal wells drilled around La Fossa cone in the 1970-80s. X-ray microtomography, an advanced imaging technique, is used to produce high-resolution (1 μm) 3D images of the volcanic rocks in a non-destructive manner. These analyses were further complemented by laboratory experiments such as uniaxial compression and tensile tests using 4D time-resolved imaging. The study of rocks microstructure and their geomechanical behaviour provided insights into the propagation of hydrothermal fluid-filled fractures within the unique tectonic context of the island. This understanding enhances our ability to identify conditions that promote instabilities and drive volcanic phreatic and phreatomagmatic unrest phenomena at Vulcano.
How to cite: Falasconi, A., Buono, G., De Astis, G., and Pappalardo, L.: Investigating hydrothermal unrest conditions of phreatic and phreatomagmatic events at Vulcano Island (Aeolian archipelago, Italy): insights from X-ray microtomography and in-situ experimental data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2272, https://doi.org/10.5194/egusphere-egu25-2272, 2025.
The explosivity of a volcanic eruption is controlled by several interdependent processes during magma ascent, such as crystallisation, gas exsolution and outgassing. Syn-eruptive crystallisation can increase the potential of magma fragmentation. Whilst the degree of coupling between the gas and melt phases during ascent can influence eruptive style. Quantitative textural analysis of vesicles and crystals in erupted products can provide insight into syn-eruptive conduit processes and the conditions leading to magma fragmentation. Synchrotron-based imaging techniques such as X-ray computed micro-tomography can provide information on vesicle and crystal size, shape and their spatial distribution in 3D. Furthermore, X-ray ptychography, an X-ray microscopy technique with nanoscale resolution, can be used to expand this 3D textural analysis to nanoscale crystals in volcanic rocks.
Here, we present a 3D reconstruction and quantification of vesicle and crystal textures in pyroclasts of the Masaya Triple Layer eruption, a highly explosive Plinian eruption of Masaya caldera, Nicaragua. Images and observations of vesicle textures at the micro-scale were acquired using X-ray computed micro-tomography and used to reconstruct the geometrical properties of the connected pore network, including connectivity, tortuosity and the throat-pore size ratio. X-ray ptychography was used to perform a 3D textural analysis of nanoscale crystals within the groundmass of clasts. These data were used to reconstruct conduit processes and evaluate the impact of syn-eruptive crystallisation, vesiculation and outgassing on magma rheology and fragmentation. Our results provide insight into the driving mechanisms of highly explosive, basaltic Plinian activity, and also highlight the potential of using multi-scale 3D imaging techniques to analyse textural features in pyroclasts and investigate controls on eruptive style.
How to cite: Bamber, E. C., Arzilli, F., La Spina, G., Polacci, M., Cipiccia, S., Batey, D. J., Mancini, L., de' Michieli Vitturi, M., Gholinia, A., Bagshaw, H., Di Genova, D., Brooker, R., Andronico, D., Corsaro, R. A., Giordano, D., Valdivia, P., and Burton, M. R.: 3D micro and nano-scale imaging of bubbles and crystals in volcanic rocks: Implications for magma rheology and ascent dynamics of highly explosive basaltic eruptions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12553, https://doi.org/10.5194/egusphere-egu25-12553, 2025.
The speciation of volatiles and metals in high-temperature fluids is unquenchable. Accordingly, it needs to be investigated in situ at high pressure (P) and temperature (T) conditions using spectroscopic techniques. One experimental apparatus frequently used for this purpose, the hydrothermal diamond anvil cell, has several limitations, including leaking, imprecise pressure control at crustal pressures and a practical upper temperature limit of ~ 700 oC. In addition, the control of redox conditions is challenging due to the reactivity of the diamonds with oxidizing fluids at high T. Furthermore, Raman spectroscopy, one of the key techniques used for in situ speciation studies at high T, suffers from elevated spectral background due to thermal incandescence of the sample above 700-800 oC when common lasers are used for excitation (e.g. 532 nm).
To alleviate these limitations, and with the particular goal of being able to study speciation in magmatic fluids at upper crustal P-T conditions at controlled fO2, we developed a new methodology that comprises a new type of externally heated pressure vessel apparatus and a custom-configured Raman spectrometer optimized for in situ high-T spectroscopy on fluid samples. Magmatic fluid analogues are sampled at high P-T and controlled redox conditions in the form of synthetic fluid inclusions (SFI) in quartz, and are subsequently reheated under the Raman microscope in a Linkam TS1500 heating stage. Upon heating, the pressure increases within the SFI to approach the entrapment P, and on the timescale of the spectroscopic experiment, the fO2 within the SFI can be maintained at a near constant value by ensuring that the surface of the quartz chip is parallel with the fast direction of hydrogen diffusion in quartz (crystallographic c-axis).
It is essential to ensure that redox-preequilibrated fluids are trapped as SFI, and therefore the quartz has to be fractured in situ during the pressure vessel experiment. To facilitate this simultaneously with redox control, we developed a new type of MHC pressure vessel apparatus, both ends open with a water-cooled pressure seals, and the capsule and a semi-permeable hydrogen membrane (Shaw-membrane) sitting in the hot spot in the middle. This included the development of a new type of Shaw membrane well-suited for operation within externally heated pressure vessels.
To facilitate the acquisition of Raman spectra with high signal-to-noise ratios at magmatic temperatures, free of the effect of thermal incandescence, we configured a high-resolution Raman spectrometer with a 405 nm laser source. This wavelength is sufficiently low to make sure that even the 3000 – 4000 cm-1 region of the Raman spectra is not affected by overlap with blackbody radiation originating from samples at T far into the magmatic T range. At the same time, it is just high enough to be usable with visible light optics carrying numerous advantages over UV systems.
The methodology was successfully used to constrain redox-dependent sulfur speciation in magmatic fluids (Farsang and Zajacz, 2025).
Farsang S. and Zajacz Z. (2025) Nature Geoscience, 18, 98-104, https://doi.org/10.1038/s41561-024-01601-3
How to cite: Zajacz, Z. and Farsang, S.: A new methodology to study element speciation in magmatic fluids, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13225, https://doi.org/10.5194/egusphere-egu25-13225, 2025.
Mineral host-inclusion systems preserve crucial information regarding their geologic history. For example, we can determine their pressure and temperature of formation with elastic geobarometry. It is possible to determine the strain of the inclusion when still entrapped in its host by measuring changes in the Raman peak positions from those of a free crystal, which are interpreted through the inclusion phonon-mode Grüneisen tensors (Grüneisen 1926). The calculated inclusion strains can then be used in an elastic model to back-calculate the pressure and temperature conditions of entrapment.
While this approach works for many host-inclusion systems (e.g., quartz or zircon in garnet), there remain several challenges. For example, when both the host and the inclusion are anisotropic, symmetry-breaking strains are generally developed within the inclusion and change the Raman peak positions, and this can lead to errors in the calculation of the inclusion strains and pressure and hence their entrapment conditions (Murri et al. 2022). Many common inclusions are solid solutions (e.g., clinopyroxenes, apatites) in which the positions of the Raman modes change as a function of their chemical composition and cation ordering. These changes must be determined before using Raman modes to determine the inclusion pressure (Baratelli et al. 2024). The thermoelastic properties of minerals also depend on their composition, so one has to know how the EoS of both the host and the inclusion depend on their composition to correctly calculate entrapment conditions (e.g., garnet solid solutions, Angel et al. 2022). The interpretation of inclusion pressures in terms of the geological history of the rock also depends on whether the inclusion stress has been reset following entrapment; for some host-inclusion systems, such as zircon in garnet, resetting is so fast on a laboratory timescale (Campomenosi et al. 2023) that measured inclusion pressures can reflect not the original entrapment, but a point on the exhumation path (Campomenosi et al. 2021).
References:
Angel, R. J., Gilio, M., Mazzucchelli, M., & Alvaro, M., 2022. Contributions to Mineralogy and Petrology, 177(5), 54.
Baratelli, L., Murri, M., Alvaro, M., Prencipe, M., Mihailova, B., & Cámara, F., 2024. American Mineralogist: Journal of Earth and Planetary Materials.
Campomenosi, N., Scambelluri, M., Angel, R. J., Hermann, J., Mazzucchelli, M. L., Mihailova, B., ... & Alvaro, M., 2021. Contributions to Mineralogy and Petrology, 176, 1-17.
Campomenosi, N., Angel, R. J., Alvaro, M., & Mihailova, B., 2023. Geology, 51(1), 23-27.
Grüneisen, E., 1926. Zustand des festen K¨orpers. Handbuch der Physik 1, 1–52
Murri, M., Gonzalez, J. P., Mazzucchelli, M. L., Prencipe, M., Mihailova, B., Angel, R. J., & Alvaro, M., 2022. Lithos, 422, 106716.
How to cite: Murri, M.: State of the art and new frontiers in the study of host-inclusion systems , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-421, https://doi.org/10.5194/egusphere-egu25-421, 2025.
The analysis of fault-related mineralization and, particularly, in the Fluid Inclusions (FIs) entrapped in synkinematic minerals are key to assess the origin and modalities of fluid circulation through fault zones. The results of these analyses, compared with those focusing on the present-day fluids, are crucial to better understanding the processes regulating both paleo and modern fluid degassing from Earth’s interior with seismicity and crustal deformation. In particular, the focus is on the role that deep fluids might have on crustal deformation over time, and hence on the processes of earthquakes nucleation and rupture propagation. In this study, we investigate the FIs of the fault-related calcite veins documented within fault-related samples collected from the Contursi hydrothermal basin of the Irpinia Region, a tectonically active area of the southern Italy characterized by fluid degassing and seismicity. The Irpinia Region was affected in 1980 by the catastrophic Mw 6.9 earthquakes, whose epicentral area was located between 1 and 5 km away from the Contursi village. There, the Contursi hydrothermal basin is characterized by a groundwater temperature ≤ 47 °C, and the outgassing of deep-sourced CO2 coupled with mantle-derived He.
The new data gathered from the study samples show presence of low salinity paleofluids (≅ 0.5 wt. % NaCleq), and two families of FIs homogenization temperatures, respectively in between 100 - 130 °C and another one at higher temperature (> 200 °C). Assuming a geothermal gradient of ~30 °C/km, we conclude that the paleofluids precipitated at depths respectively of ca. 3 ~ 4 km, and ca. 8 ~ 10 km. Noble gases in FIs show a wide range of R/Ra values (0.09 – 1.38 Ra) and taking the SCLM component as reference (6.1 Ra value) the FIs are characterized by a predominant crustal contribution and a mantle contribution (up to 20%) with a local atmospheric-derived fluids. The highest He isotopic ratio measured in FIs (1.38Ra) fits well with the values that characterize the current high-flux CO2 gas emission recorded in the study area (1.41 Ra). Such a similarity is interpreted as due to a ratio of crust-to-mantle He that remained approximately constant over time in the study area. The isotopic variability in FIs could be due to early trapping processes and, potentially, to paleo earthquakes associated to extensional faulting which ruptured the subsurface impermeable horizon provided by the tectonic mélange, and eventually allowed the ascendance of deep-warm fluids. The high transmissibility pathway of the ascending fluids is still active in the area, as suggested by the results of soil gas measurement, thus indicating that the current outgassing of mantle derived fluids could be associated to a long-lasting crustal process.
Amoroso et al., 2017 (Geophysical Research Letters)
Buttitta et al., 2023 (Science of the Total Environment)
Schirripa Spagnolo et al., 2024 (Earth and Planetary Science Letters)
Zummo et al., 2024 (Geochemistry, Geophysics, Geosystems)
How to cite: Zummo, F., Agosta, F., Álvarez-Valero, A., Billi, A., Buttitta, D., Caracausi, A., Carnevale, G., Marchesini, B., and Paternoster, M.: New insights into the assessment of mantle component in the paleo fluids that circulated along seismically active extensional faults, Irpinia Region, Italy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7136, https://doi.org/10.5194/egusphere-egu25-7136, 2025.
Posters on site: Thu, 1 May, 14:00–15:45 | Hall X2
The EXCITE² Network is transforming Earth and environmental material science with transnational access to 36 worldclass European imaging facilities in 19 research institutes across 12 European and partner countries. Researchers anywhere can now explore complex processes in Earth materials across scales ranging from nanometers to decimeters. This yields unprecedented insights into critical areas such as environmental toxicity and human health, sustainable extraction of critical metals for renewable energy, and safe long-term storage of climate-relevant gases.
EXCITE² also brings together expertise and pioneers innovative services, tools, and training, to enhance the ability of users to address complex scientific challenges. To this end, EXCITE² will launch the ‘EXCITE Academy’ in the Spring of 2025, an open community and collaborative platform for sharing knowledge, tools, experiences and expertise via live and online events as well as an open online searchable database: the ‘Academy Hub’. Innovative services and tools include AI-driven data analysis and next-generation imaging technologies.
By fostering interdisciplinary collaboration between academia, industry, and diverse scientific fields, EXCITE² accelerates innovation and strengthens Europe's position in global sustainability efforts. The initiative actively supports capacity building through tailored training programs for early-career researchers, fully embedded within the principles of European open science.
Through its commitment to scientific excellence, sustainability, and societal impact, EXCITE² is shaping the future of Earth and environmental research. Interested in joining the network? Apply for transnational access via our open call! Visit the EXCITE² website (https://excite-network.eu) for more information.
How to cite: van der Poel, S., ter Maat, G., Plümper, O., and Wessels, R.: The EXCITE² Network, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11434, https://doi.org/10.5194/egusphere-egu25-11434, 2025.
There is increasing evidence that the primary magmas at the origin of low-silica alkaline volcanism, such as basanites, are very rich in CO2 and that they can rise rapidly, directly from the mantle to the Earth’s surface. Such volcanic systems are numerous in intraplate oceanic and continental settings, including the French Massif Central, and some are remarkable for the abundance of large mantle-derived xenoliths. Although they usually represent relatively modest volumes of magma, their eruptions constitute a real and specific volcanic threat because of (1) their high ascent rate, with magmas capable of rising from mantle depths to the surface in less than a day to a few days, (2) the large volumes of CO2 emitted into the atmosphere at the time of eruption, and (3) the effusion of very fluid lava flows. The recent part of the Cézallier volcanic province, French Massif Central, offers nice examples of such low-silica alkaline volcanoes that erupted less than 200 ka ago.
A study of fluid and melt inclusions has been carried out on three volcanoes from the recent part of the Cézallier volcanic province (Sarran, Mazoires, La Godivelle) in order to characterize the composition of primary magmas and to provide constraints on magma storage and ascent. Mg-rich olivine crystals (forsterite contents in the range of 83-89) were selected for the study of melt inclusions, while CO2-rich fluid inclusions were analyzed in olivine, pyroxene and amphibole crystals. After in-depth petrographic characterization, the melt inclusions were characterized using a series of analytical techniques, including: X-ray tomography (to characterize the shape and volume of melt inclusions and shrinkage bubbles); electron probe microanalysis (for major elements, Cl, F, S in glasses); Raman spectroscopy (to measure H2O and CO2 in glasses and to characterize the CO2-bearing phases in the shrinkage bubbles of the melt inclusions); and LA-ICP-MS (for trace elements). Microthermometry was used to measure CO2 densities in fluid inclusions, which were thereafter converted into pressures and into depths.
The glass compositions of the melt inclusions plot into the fields of basanites, basalts and trachy-basalts. The glasses have particularly high CO2 contents: up to 1.8 wt% dissolved CO2. These values are minimum values, as CO2 is also present in the shrinkage bubbles as a fluid phase and as microcrystals of carbonates (Mg-calcite, nahcolite, ferromagnesite) covering the bubble walls. These high CO2 contents imply that the mantle sources at the origin of these magmas were enriched in carbon. CO2-rich fluid inclusions in olivine, pyroxene and amphibole crystals are all re-equilibrated and have thus lost their primary densities. At all three volcanoes, the CO2 density histograms show a major peak at 900 to 1090 kg/m3 (» 750 to 900 MPa), indicating a stage of magma storage at Moho level followed by rapid ascent to the surface. Work is in progress to reconcile the observation of large peridotite xenoliths (at Mazoires) with magma storage at Moho level.
How to cite: Barreau, L., Laporte, D., Cluzel, N., Zanon, V., Schiavi, F., Falvard, S., Merciecca, C., and Devidal, J.-L.: Combined analysis of melt and fluid inclusions in recent Cézallier volcanoes, French Massif Central: from mantle melting to magma storage and ascent, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11940, https://doi.org/10.5194/egusphere-egu25-11940, 2025.
In recent decades, image analysis has been consolidated as a standard quantitative method. However, with a few exceptions, this analysis has predominantly relied on laborious and highly dependent human expert intervention. Consequently, physicochemical methods, which can be more readily automated for the analysis of large sample sets, have been the most commonly employed approach to provide scientific evidence. This tendency is particularly pronounced in the field of geosciences, where the analysis of light and SEM microscopy images of thin rock layers is informative but can only be performed on a limited number of samples, thereby compromising conclusions at larger scales. In recent years, advancements in artificial intelligence have elevated image analysis to a new level by automating human interpretation, thereby enabling the processing of a greater number of samples. In this study, we examine the Segment Anything for Microscopy (micro-sam) package, which is based on the widely used deep learning tool Segment Anything Model (SAM), to assess its practical application in the analysis of SEM images of thin layers of volcanic rock samples.
To this end, we have first conducted a grid search of the best SAM parameter values using a set of three SEM images, exploring the impact of the different SAM parameter sets on automatic mask generation. We generated a data set comprising more than 300 objects per image by interactive delineation and identification ("labeling"), and used this data set to evaluate the results and identify the best sets of parameter values for each image, as well as common sets that provided good results across all three images. A common set of parameter values was then used to compare the results obtained from the three available SAM models. The findings of this study indicate that two distinct sets of parameter values are particularly noteworthy. The first set leads to maximized object detection, which is intended to be subsequently used for automatic instance segmentation through deep-learning methods. The second set produces severe object over-segmentation with a very low error rate, making it useful for subsequent classification. Furthermore, we have investigated the micro-sam capabilities of custom fine-tuning by employing our labeled objects as a training set.
The preliminary findings indicate that deep-learning methodologies, such as micro-sam, can be efficiently implemented for the analysis of SEM images of thin layers of volcanic rock samples. This approach will lead to a substantial increase in the number of analyzed images, provided that appropriately labeled objects are fed to the system. This strategy notably enhances the cost-efficiency of the time invested by experts. In alignment with current practices in related domains, experts in the analysis of these images should collaborate in a concerted manner to generate shared training sets and artificial intelligence models.
This research was partially supported by the HYDROCAL (PID2020-114876GB-I00) grant funded by MICIU/AEI/10.13039/501100011033.
How to cite: Lobo, A., Geyer, A., and Ortiz-Rosell, C.: AI-driven analysis of SEM images of thin layers of volcanic rocks: a test with Segment Anything for Microscopy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12779, https://doi.org/10.5194/egusphere-egu25-12779, 2025.
Failure of glowing volcaniclastic rocks can result in hot rock avalanches, commonly referred to as deposit-derived pyroclastic density currents (PDCs). These phenomena are common in volcanoes with low to moderate eruptive activity, where steep slopes and proximal material accumulation near eruptive vents predispose volcanic flanks to instability. To investigate the factors influencing these failures, we studied the welded deposits from the 1944 eruption of Mt. Vesuvius, which produced deposit-derived PDCs along the volcano's slopes. Our analyses include the physical, mechanical and compositional characterization of proximal fire-fountaining deposits, with particular emphasis on the influence of variations in welding degree, porosity and crystallinity at high temperatures. Field and laboratory tests were carried out to investigate the physical (porosity measurements) and mechanical (i.e., sclerometer measurements, point load tests, and uniaxial compression tests) properties. Petrographic observations were carried out using transmitted light microscopy, supplemented by scanning electron microscopy (SEM) to examine textural and morphological characteristics. The composition of mineral phases was obtained through electron microprobe (EPM), while the abundance of major and trace elements in whole rocks was determined using X-ray Fluorescence (XRF) and inductively coupled plasma (ICP) spectroscopy.
High-temperature rheological experiments were carried out using a newly developed apparatus, the Volcanological In-situ Deformation Instrument (VIDI), designed to study magma rheology under conditions relevant to volcanic processes. VIDI allows vertical uniaxial deformation experiments on natural silicate melts at temperatures up to 1100°C. The experiments were performed on partially remelted samples with varying welding degrees, including (i) coherent lava blocks or pyroclastic bombs and (ii) partially welded pyroclasts. These investigations explored the rheological response of multiphase materials (comprising melt, crystals and pores) in different regimes ranging from homogeneous to inhomogeneous deformation, the latter characterised by viscous and brittle shear localisation. The flow curves generated from these high temperature deformation experiments defined the uniaxial strength of the materials at elevated temperatures. Additionally, the experiments quantified material weakening caused by shear band formation and ductile deformation. To further constrain the textural and porosity changes experienced by the samples, X-ray microtomography imaging analysis was carried out both before and after the experiments. This analysis provided valuable insights into the microstructural evolution of the materials during deformation. These results elucidate the mechanical processes that contribute to the failure of incandescent volcaniclastic rocks and the generation of deposit-derived PDCs, thereby advancing our understanding of instability dynamics in volcanic systems and provides critical insights into the hazards posed by such phenomena.
How to cite: Grillo, T. O., Calandra, S., Servatici, T., Falasconi, A., Frontoni, A., Buono, G., Pappalardo, L., Romano, C., Santo, A. P., Giordano, G., Intrieri, E., Vona, A., and Di Traglia, F.: Mechanical Behaviour and Failure of Glowing Volcaniclastic Rocks: Implications for Deposit-Derived Pyroclastic Density Currents, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12016, https://doi.org/10.5194/egusphere-egu25-12016, 2025.
Ultramafic rocks in ophiolites are known as source rocks of abiotic hydrogen (H2) and methane (CH4), due to serpentinization and successive CO2 hydrogenation. Ophiolites are therefore key targets in natural hydrogen exploration. While serpentinized peridotites are the main sources of H2, chromitites host both hydrogen and large quantities of methane, as revealed by analyses of direct gas extraction from rocks and micro-Raman analyses.
However, the fluid bearing properties of chromitites, as well as their mineralogical phases that are correlated to gas genesis and evolution are unclear. We conducted high-resolution X-ray computed micro-tomography (microCT) on chromitite samples from two ophiolites in Greece. The microCT analysis, using the X-ray attenuation coefficient (which is density-dependent), combined with 3D image analysis and pore-scale permeability simulations, revealed the geometry and distribution of pores and microfractures. This approach provided insights into their flow properties and spatial relationships with solid phases that could act as catalysts for CH4 production (Platinum Group Elements - PGM), H2 flow (altered PGM), and CO2 hydrogenation (amorphous carbon).
Microfractures appear as potential sites or microreactors for H2-CO2 conversion into CH4, while also retaining residual, unreacted H2. The microCT technique provides insights into the in-situ textural relationship between microfractures, gas pores and solid phases, unattainable through 2D traditional techniques, thus offering a valuable support for natural hydrogen exploration.
How to cite: Pappalardo, L., Buono, G., Procesi, M., and Etiope, G.: The link between ophiolitic chromitites, natural hydrogen and methane:Insights from 3D microtomography, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12979, https://doi.org/10.5194/egusphere-egu25-12979, 2025.
Bubble nucleation is a key process in controlling volcanic fragmentation, eruption dynamics, and magma degassing efficiency. Understanding the nanoscale mechanisms of bubble formation is essential for advancing models of eruptive behavior and hazard prediction.
We performed in-situ high-temperature small-angle X-ray scattering (HT-SAXS) experiments to investigate the nucleation and growth of bubbles in a hydrous volcanic glass sample from Tenerife. This study integrated HT-SAXS with low-frequency Raman spectroscopy, DSC-TGA, TEM, high-temperature elastic property measurements, and rheological analyses to analyze porosity evolution and its influence on magma dynamics.
Thermal treatment revealed a significant increase in porosity beyond 700 °C, corresponding to the rapid formation of voids between 50 and 100 nm driven by vapor pressure surpassing the atmospheric threshold. Smaller pore populations (10 nm) exhibited negligible changes, suggesting selective growth mechanisms under HT conditions.
Our findings provide new insights into the nanoscale processes governing bubble nucleation in volcanic glasses, emphasizing their role in porosity development, elastic properties, and the potential impacts on eruptive behavior. This multi-method approach establishes a framework for understanding the interplay between thermal dynamics and volcanic fragmentation.
Contribution of PRIN2022PXHTXM- STONE project, funded by EU - NextGeneration, PNRR-M4C2- CUP: D53D23004840006
How to cite: Cassetta, M., Peterlik, H., Haßler, M., Daldosso, N., and Giordano, D.: Nanoscale evolution of bubbles in volcanic glasses, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18389, https://doi.org/10.5194/egusphere-egu25-18389, 2025.
Atom Probe Tomography (APT) enables high-resolution elemental analysis at the nanoscale, making it an essential tool in Earth sciences. Recent advancements have focused on trace element distribution, mineral element migration, and water content analysis at the nanoscale. In this study, we present APT-based techniques for analyzing trace element enrichment in arsenian pyrite, water content and occurrence in glass, and isotope analysis with nanometer resolution.
Arsenian Pyrite in Carlin-type Gold Deposits:
We investigated arsenian pyrite with banded structures from a Carlin-type gold deposit using APT combined with SEM-EBSD, EPMA, LA-ICP-MS, and STEM. This multi-method approach revealed the structural and compositional characteristics of pyrite at micro- to nanoscale resolutions. Our findings show that Au, As, and Cu are hosted in pyrite in a substitutional form, while Sb, Pb, Hg, and Tl are concentrated as non-structural impurities in lattice defects. The accumulation of trace elements is coupled with the formation of lattice defects during pyrite’s growth, which transitions from a layered to an island-like growth pattern and back to a layered structure. The study also highlights the crucial role of As in promoting metal enrichment, and surface adsorption of Au as a key mechanism for gold mineralization.
Water Content and occurrence in Glass:
We applied APT in combination with NanoSIMS to study the nanoscale water content, occurrence, and distribution in water-bearing glass samples. The detection limit was achieved down to 0.02 at% for hydroxyl water. We identified nano-sized hydroxyl-water inclusions in glass, with higher hydroxyl water content in these inclusions correlating with increased water content in the surrounding glass. This demonstrates APT’s ability to analyze nanoscale water content and to distinguish hydroxyl water and nano-sized inclusions in mineral samples.
Silicon Isotope Analysis:
APT was also used to analyze silicon samples, including both standard pure silicon and silicon with different isotope ratios. After background correction and mass ranging, we achieved precise nanoscale isotopic ratio analysis. Studies on AVO28 and UHP silicon samples revealed homogeneous distribution of isotopes at the nanoscale without impurities. Our results matched those obtained by MC-ICP-MS and SIMS, demonstrating APT's potential to provide high spatial resolution isotopic analysis for geological sample analysis.
In conclusion, APT offers a powerful tool for exploring nanoscale trace elements, water content, and isotope ratios in geological samples, advancing our understanding of Earth and planetary materials.
How to cite: Long, T., Wang, Y.-Y., Gao, Y.-Y., Ren, T.-X., Che, X., Xie, S., and Liu, D.: Applications of Atom Probe Tomography in Earth Sciences, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19996, https://doi.org/10.5194/egusphere-egu25-19996, 2025.
The Campi Flegrei caldera (CFc), one of the highest risk volcanic areas on Earth and the most dangerous volcano in Europe, originated from two large-scale caldera-forming eruptions occurred 40 and and 15 ka. Since 2005, it has been experiencing a new phase of unrest manifested by intensified ground uplift, seismicity and hydrothermal activity. The aim of this study is to investigate the magma volatile content and composition in pre-eruptive conditions through the study of melt inclusions in phenocrysts of pyroclastic rocks erupted in the last 15 ka. Study samples were collected from different deposits of several representative eruptions (Baia, Averno 2, Fondo Riccio, Minopoli, Astroni, Agnano-Monte Spina, Montagna Spaccata, St. Teresa, Nisida). Sixtyfive melt inclusions within olivine, clinopyroxene and alkali feldspar phenocrysts (perfectly glassy, regular shape, 20-30 µm in size, one or two fluid bubbles) representative of the studied eruptions were selected by microscope analysis. Image analyses performed on the inclusions allowed us to determine the ratio between the volume of the fluid bubble and glass in each inclusion. A comprehensive geochemical characterization of the melt inclusions has been systematically conducted using a combination of Raman spectroscopy, electron microprobe, laser ablation-inductively coupled mass spectroscopy, and nano secondary ion mass spectrometry. Such a complete dataset lays the foundation for a thorough investigation of the architecture and dynamics of the shallow CFc magma storage system, as well as for formulating pre-eruptive scenarios in the CFc active volcanic area.
How to cite: Baccari, C., Buono, G., Di Vito, M. A., Pappalardo, L., Petrosino, P., and Zanon, V.: Exploring the pre-eruptive magmatic processes through melt inclusions: the case study of the Campi Flegrei Caldera., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9220, https://doi.org/10.5194/egusphere-egu25-9220, 2025.
The investigation of rutile inclusions in garnet host crystals is a rewarding topic, as this host-inclusion system may form in igneous and metamorphic lithologies in a wide range of rock compositions and pressure - temperature conditions. Different formation mechanisms have been discussed for the genesis of rutile inclusions in garnet, as for example overgrowth of pre-existing rutile by garnet, co-growth of host and inclusion phases, or exsolution of rutile from titanium-bearing garnet host crystals (Kohn et al., 2024b, with references).
The investigated rutile-bearing almandine-spessartine garnet crystal from the Moldanubian Gföhl Unit Bohemian Massif, AT, formed in three growth stages during fractional crystallization of a pegmatoid melt (Kohn et al., 2024a). Here, we focus on the first magmatic growth stage, which formed the core and inner rim domain of garnet, without significant changes in pressure-temperature conditions. This is reflected by the lack of an abrupt change in the major garnet components across the core-rim boundary of garnet. Instead, a gradual change of major element composition continues undisturbed across the boundary. However, the microstructural change (size and habit) of rutile inclusions is significant: while the coloured garnet core bears equant rutile inclusions (80 - 200 nm), the uncoloured rim is dominated by needle-shaped rutile (< 150 µm length, c. 200 nm width) with clear shape preferred orientations (SPOs). The microstructural differences correlate with abrupt changes in trace element composition of garnet (Na2O and OH-content relatively higher in the rim than in the core), which are referred to compositional changes of the pegmatoid melt during fractional crystallization.
The synchronous formation of rutile inclusions and their garnet host crystal can be demonstrated on the basis of a statistical dataset of the SPOs of rutile inclusions with high aspect ratio, showing a selective effect of the local garnet growth direction on the observed SPO frequencies (Kohn et al. 2024b). Changes of the rutile inclusion habit from equant to acicular signals changes in the relative growth rates of garnet and rutile, as well as the nucleation rate of rutile, resulting from a reduction of the melt viscosity.
Comparable microstructural changes (equant to acicular rutile inclusions, from the core to the rim of garnet) are also documented in a metapegmatite from the Austroalpine Crystalline Basement, Koralpe, AT (Griffiths et al., 2020), separated in time and space from the studied lithology. Therefore, we conclude that the described microstructure of rutile inclusions in pegmatoid garnet is a potential marker of changes in melt properties upon fractional crystallisation of pegmatitic melts, which are not documented by the major garnet components.
Funded by Austrian Science Fund (FWF): I4285-N37.
References
Griffiths T.A. et al (2020) American Journal of Science 320:753–789
Kohn V. et al (2024a) Lithos 466–467, 107461
Kohn V. et al. (2024b) Contributions to Mineralogy and Petrology 179, 69
How to cite: Kohn, V., Griffiths, T. A., Abart, R., and Habler, G.: Rutile inclusions in garnet: Inclusion microstructure as monitor of pegmatoid melt fractionation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20815, https://doi.org/10.5194/egusphere-egu25-20815, 2025.
Although the faults geometry is generally approximate by 2-D models, when considering fluids circulation in porous media is fundamental to have instead a 3-D view of the area under study, to better evaluate the non-uniform behavior of the circulation and the inhomogeneous distribution of the possible correlated seismogenetic structures. Our research was aimed at studying the Ischia Island faults systems, and particularly the Lacco-Ameno system affected by volcanic gas emissions, mainly CO2 and H2O, coming from depth. We have modeled the flux of these magmatic fluids via the 3_D geothermal simulator TOUGH2 code, able to consider non-isothermal flows of multi-component (water and carbon dioxide), multiphase (gas and liquid) fluids, in porous and fractured media. Based on the measured flux of these two components at the surface, and assigning different permeability values between the fault and the host zone, we have estimate, via a 3-D Voronoi tessellation, the magnitude of the released energy by the deep source (H2O and CO2 enthalpy injected at depth) and the distribution of the pressure and temperature along the fault-zone, which could be correlated with the not uniform earthquakes location distribution.
How to cite: Mangiacapra, A., Petrillo, Z., Scippacercola, S., Tripaldi, S., and Caliro, S.: A 3D geothermal simulation applied to the Lacco Ameno (Ischia island, Italy) faults system. , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7044, https://doi.org/10.5194/egusphere-egu25-7044, 2025.
Studying volcanic CO2 releases during geological periods is essential for unraveling the complex interactions between Earth's interior, atmosphere, oceans, and biosphere. Such studies provide critical insights into the mechanisms driving climate change, mass extinctions, and the evolution of life on Earth. The uplift of the Tibetan Plateau has had a significant impact on global climate change, yet the assessment of CO2 releases from contemporaneous volcanic activities has received relatively little attention.
Melt inclusions trapped within phenocryst minerals of volcanic rocks represent a unique and powerful tool for studying the origin and evolution of magma. They also serve as direct evidence for investigating CO2 releases from volcanic activity. In this study, we focus on the post-collision volcanic rocks of the Lhasa terrane (12–15 Ma) and the Qiangtang terrane (35–40 Ma) in the southern Tibetan Plateau. We characterized olivine- and pyroxene-hosted melt inclusions, determined the CO2 content in bubble melt inclusions, and calculated the total CO2release. Our results show that the average CO2 content in volcanic rocks is approximately 1.73 ± 0.59 wt% in the Lhasa terrane and 0.46 ± 0.30 wt% in the Qiangtang terrane. Based on the estimated volumes of volcanic rocks, we calculated the CO2 fluxes from post-collision volcanic activities in the Lhasa and Qiangtang terranes to be 0.151 ± 0.052 Pg yr⁻¹ and 0.047 ± 0.007 Pg yr⁻¹, respectively.
When combined with previous estimates of CO2 emissions from the Linzizong volcanic rocks (~50 Ma) in the Qiangtang terrane, our findings reveal that the total CO2 release from the Qiangtang terrane exceeded that from the Lhasa terrane. This pattern aligns with the global cooling trend and declining atmospheric CO2 levels observed between the Eocene and Miocene. We propose that the elevated atmospheric CO2 concentrations during the Middle Eocene Climatic Optimum (~40 Ma) were likely driven by volcanic activity from the Linzizong and Qiangtang volcanic eruptions. Similarly, volcanic activity in the Lhasa terrane may have contributed to the elevated CO2 levels observed during the Middle Miocene Climatic Optimum. Although uncertainties remain, our results provide preliminary data for modeling deep-sourced CO2 emissions associated with the India-Asia collision during geological history.
How to cite: Xu, S., Xie, X., Zhao, W., Zhang, M., Lang, Y.-C., and Guo, Z.: Melt inclusion constraints on volcanic CO2 releases from the Tibetan Plateau, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11232, https://doi.org/10.5194/egusphere-egu25-11232, 2025.
This study employs Raman spectroscopy to measure the density of CO2 inclusions trapped in olivines and pyroxenes from Cenozoic volcanic rocks of the Strzelin Volcanic Field, a part of the Central European Volcanic Province (CEVP). In this region, monogenetic volcanic fields are the most common manifestation of intraplate alkaline basaltic volcanism, which is usually linked to lithospheric extension, melting of upwelling asthenosphere, and interaction between lithospheric and asthenospheric melts. Rocks from the SW Poland show characteristics of mantle sources that are among the least enriched. Nephelinites, basalts and trachybasalts in the Strzelin Field scoria cones and lava flows show evidence of variable differentiation during magma rise towards the surface, but important details, such as storage and crystallization depths of magma, remained poorly constrained.
The study of the density of CO2 inclusions is crucial for determining the ascent history of magma, the depths and conditions of crystallization and the structure of magmatic systems. The Raman spectrum of CO2 consists of two characteristic peaks at ca. 1285 and 1388 cm⁻¹ (Fermi Diad). The distance between these peaks is directly proportional to the density of the inclusion which increases with entrapment pressure and thus, it is possible to calculate the pressure at which the inclusion was sealed. Combined with the temperature of inclusion formation, this method provides a reliable and rapid geothermobarometer, offering insight into the dynamics of magmatic processes.
Preliminary results of our study of 45 inclusions in 8 olivine phenocrysts in nephelinite suggest that magma crystallization occurred at depths of ca. 23-24.5 km. These values correspond to lower to middle crustal levels in this area and thus to relatively deep parts of the magmatic systems. Further studies of nephelinites, as well as basalts and trachybasalts (which represent more evolved compositions that resulted in more explosive eruptions), should reveal more details about the magmatic systems, their structure and evolution, and their influence on the eruptive processes in this region.
How to cite: Stolarczyk, K. and Awdankiewicz, M.: Magmatic Evolution of the Cenozoic Strzelin Volcanic Field (SW Poland) – preliminary results from Raman spectroscopy of CO2 inclusions in mafic phenocrysts, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19217, https://doi.org/10.5194/egusphere-egu25-19217, 2025.
The Lamb relation is a powerful tool for estimating nanoparticle sizes from vibrational spectra by analyzing the particle modes in the low-frequency region of the Raman spectrum. This approach has long time been applied to investigate the structural evolution of nano-structured silicate glasses. By linking shifts of the nano-particle mode maximum to nanoparticle’s material sound velocities, the Lamb relation provides precise size characterization within glass matrices.
A body of research has demonstrated the utility of this method in contexts such as the study of glass doped with silver through ion exchange and thermal treatments. These studies have revealed key insights into nanoparticle clustering and growth processes, influenced by temperature and local dopant concentrations.
For volcanologists, applying the Lamb relation could provide a robust approach to examining nanoscale processes in volcanic glasses. Estimating nanoparticle sizes allows for a better understanding of clustering phenomena and their influence on the mechanical and rheological properties of volcanic materials. This knowledge improves predictive models of volcanic behavior, offering valuable tools for interpreting eruption dynamics and enhancing hazard assessments.
How to cite: Mariotto, G. and Daldosso, N.: Using the Lamb Relation to Investigate Nanostructures in Silicate Glasses, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19736, https://doi.org/10.5194/egusphere-egu25-19736, 2025.
Diamond-hosted inclusions offer critical insights into Earth's interior, serving as tracers of entrapment pressure (P) and temperature (T) during diamond formation. These inclusions preserve residual pressures, crucial for reconstructing deep-Earth processes through geothermobarometry (Kohn et al., 2023; Rustioni et al., 2015). However, current models assume purely elastic post-entrapment behavior, overlooking mechanisms like brittle fractures and viscous deformation, potentially underestimating formation depths (Angel et al., 2022). This study models brittle fractures in diamond-hosted inclusions to refine geothermobarometric techniques.
Using Extended Finite Element Methods (XFEM) (Moës et al., 1999) and Phase-Field Modeling (PFM) (Wu, 2017), we analyzed the interplay between inclusion geometry, material properties, and fracture behavior. XFEM simulations revealed brittle fractures contribute marginally (~5–6%) to residual pressure relaxation, leaving pressures significantly higher (~0.76 GPa) than observed in natural systems (<0.5 GPa). These findings highlight limitations in brittle fracture assumptions and emphasize the influence of inclusion size and shape on stress concentration and fracture propagation (Puhan et al., 2024).
To address XFEM’s limitations, PFM simulations incorporating brittle and quasi-brittle fractures were implemented within an ABAQUS framework. Results showed geometric singularities, such as sharp edges in cuboidal inclusions, enhance pressure relaxation (~0.72 GPa), aligning better with experimental observations. Stress interactions in multi-inclusion systems demonstrated fracture coalescence as a key mechanism for additional relaxation. However, these effects remain insufficient to fully explain the lower residual pressures observed in natural systems.
This study explores the influence of inclusion size, fracture toughness, and material properties on fracture initiation and propagation. It identifies the need for additional mechanisms, such as fluid-mediated weakening, plastic deformation, and preexisting defects, to accurately capture the complexity of natural inclusion-host systems. By advancing numerical methodologies and addressing critical gaps in current models, this work provides a robust framework for refining geothermobarometric methods and deepening understanding of diamond formation and exhumation processes.
References
- Angel, R. J., Alvaro, M., & Nestola, F. (2022). Crystallographic Methods for Non-destructive Characterization of Mineral Inclusions in Diamonds. Reviews in Mineralogy and Geochemistry, 88(1), 257–305. https://doi.org/10.2138/rmg.2022.88.05
- Kohn, M. J., Mazzucchelli, M. L., & Alvaro, M. (2023). Elastic Thermobarometry. Annual Review of Earth and Planetary Sciences, 51(1), 331–366. https://doi.org/10.1146/annurev-earth-031621-112720
- Moës, N., Dolbow, J., & Belytschko, T. (1999). A finite element method for crack growth without remeshing. International Journal for Numerical Methods in Engineering, 46(1), 131–150. https://doi.org/10.1002/(SICI)1097-0207(19990910)46:1<131::AID-NME726>3.0.CO;2-J
- Puhan, B., Patton, A., Morganti, S., Rustioni, G., Reali, A., & Alvaro, M. (2024). Investigation of microscale brittle fracture opening in diamond with olivine inclusion using XFEM and cohesive zone modeling. Engineering Fracture Mechanics, 110713. https://doi.org/10.1016/j.engfracmech.2024.110713
- Rustioni, G., Angel, R., Milani, S., Mazzucchelli, M., Nimis, P., Domeneghetti, M., Marone, F., Alvaro, M., Harris, J., & Nestola, F. (2015). Elastic geobarometry for host-inclusion systems: Pressure release and the role of brittle failure. Rendiconti Online Della Società Geologica Italiana, 35, 137.
- Wu, J.-Y. (2017). A unified phase-field theory for the mechanics of damage and quasi-brittle failure. Journal of the Mechanics and Physics of Solids, 103, 72–99. https://doi.org/10.1016/j.jmps.2017.03.015
How to cite: Puhan, B., Alvaro, M., Patton, A., Reali, A., and Morganti, S.: Investigation of microscale brittle fracture opening in diamond with olivine inclusion using advanced computational modelling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12235, https://doi.org/10.5194/egusphere-egu25-12235, 2025.
Geophysical studies of subduction zones have identified deep episodic tremor and slow slip events (ETS), which frequently occur at depths >30 km in subduction zones. Recently, considerable attention has been devoted to the geological records of these events, with a particular focus on crack-seal fluid-mediated vein formation characteristic of these environments.
In this study, we examined continental metasediments from the Northern Apennines, Italy, where crack-seal quartz-carpholite veins are extensively developed. These dilational hydroshear veins predominantly align with the metamorphic foliation and consist of iso-oriented quartz and carpholite fibres. Thermodynamic modelling indicates that the formation of these veins and the associated mylonitic foliation occurred under high-pressure, low-temperature conditions (~1 GPa and 300–350°C), fitting to the identified ETS conditions in subduction zone.
The study emphasizes determining the composition and origin of fluids entrapped as fluid inclusions during the formation of quartz-carpholite veins. Raman spectroscopy revealed variability in the composition of the biphasic fluid-gas inclusions, showing commonly contents of H2O, CO2, alkanes (CH4), and N2. The research also focuses on reconstructing the major and trace element migration associated with the development of these fluid-mediated veins and examining the incorporation of trace elements into vein-associated phases (primarily carpholite). Elemental analyses conducted using WDS-EPMA and LA-ICP-MS revealed correlations and anti-correlations between trace elements, providing insights into the operating conditions, transferability and availability of elements during dilational hydroshear vein formation.
In-situ δ18O SIMS measurements constrain values between +18.4 and +19.2 ‰ for the quartz fibres in the veins. δ18O bulk rock analyses by laser fluorination range between +12.3 and +15.7‰ for the host metasediments and ca. +14‰ for the adjacent metabasites. These results suggest that the fluids responsible for vein formation were in O-isotope disequilibrium with the surrounding rocks, indicating at least partly derivation from an external source.
In conclusion, the study identifies the geochemical characteristics of fluid inclusions and pathways in deeply subducted metasedimentary rocks with quartz-carpholite veins, tracking forming conditions of a fossil record of deep ETS in subduction zones.
How to cite: Kulhánek, J., Giuntoli, F., Boschi, C., Rubatto, D., and Cannaò, E.: Geochemical Study of Fluid Pathways in Dilational Hydroshear Veins: A Record of Fossil Tremor and Slow Slip Events in Subduction Zones, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-945, https://doi.org/10.5194/egusphere-egu25-945, 2025.
Posters virtual: Tue, 29 Apr, 14:00–15:45 | vPoster spot 1
EGU25-8768 | Posters virtual | VPS22
A Method for Measuring Viscosity of Silicate Melts Using Hot Stage Microscopy (HSM)Tue, 29 Apr, 14:00–15:45 (CEST) | vP1.4
The viscosity of silicate melts is one of the most important physical parameter governing natural processes such as volcanic eruptions, as well as manufacturing processes in the ceramic and glass industries. The traditional techniques for measuring viscosity are commonly time- and energy-consuming, they require equilibrium conditions, and are mostly limited to reduced viscosity intervals. Reducing testing time is a critical target for both academic and productive purposes. In order to calibrate an efficient tool capable of both reducing testing time and expand the range of viscosity determination, we used the hot stage microscope (HSM) technique. Specimens (pressed powders) of natural samples, previously measured employing a combination of concentric cylinder and the micropenetration dilatometric techniques, were heated at a rate of 10°C/min until melting. Characteristic shapes (Start sintering, End sintering, Softening, Sphere, Hemisphere, and Melting) were observed at characteristic temperatures (CT); then their viscosities were calculated from their known viscosity-temperature (Vogel-Fulcher-Tammann, VFT) relationships. The observed shapes result from a combined effect of viscosity and surface tension, allowing viscosity values at each CT to linearly scale with surface tension. Viscosity was calibrated by introducing correction factors based on glass chemistry. This approach provides two independent data sets – CT (from HSM) and the corresponding characteristic viscosity (from glass composition) – which can be used to calculate the VFT parameters. The comparison between calculated and experimental viscosity shows good correspondence, which significantly improved previous attempts using only HSM data. These results also highlight the potential of this non-contact technique for evaluating the effects of crystalline particles and porosity on the rheological properties of alumosilicate melts.
Contribution of PNRR M4C2 - PRIN 2022PXHTXM - STONE project, funded from EU within the Next generation EU program. CUP: D53D23004840006
How to cite: Giordano, D., Molinari, C., Dondi, M., Conte, S., and Zanelli, C.: A Method for Measuring Viscosity of Silicate Melts Using Hot Stage Microscopy (HSM), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8768, https://doi.org/10.5194/egusphere-egu25-8768, 2025.
EGU25-8978 | Posters virtual | VPS22
Characterization of Residual Glass Evolution from Vitrified Ceramics: Insights from Raman Spectroscopy and DSC into Viscous and Elastic PropertiesTue, 29 Apr, 14:00–15:45 (CEST) | vP1.5
Four multicomponent metaluminous glasses were designed to investigate the evolution of residual glass-ceramics comprising glass and crystals. Samples were obtained from melting of quartz-feldspars mixes (with varying Na/K ratio and silica content) further fast sintered at temperatures of 1200-1260°C. Using an integrated approach combining high- and low-frequency Raman spectroscopy and Differential Scanning Calorimetry (DSC), we characterized the viscous and elastic response of the residual glass and its role in the mechanical properties of the corresponding ceramic products.
High-frequency Raman spectroscopy allows for the analysis of Qn species, which represent the polymerization state of the glass network. Q0, Q¹, Q², Q³, and Q4 correspond to isolated tetrahedra, short chains, branched structures, and fully polymerized networks, respectively. This provides insights into how chemical composition affects the microscopic structure of the residual glass. Simultaneously, low-frequency Raman spectroscopy probes the boson peak, a signature of collective vibrational modes in the glass, which is directly linked to its elastic properties. By coupling the boson peak analysis with the elastic medium scaling law, we determine the vibrational density of states and shear modulus, key parameters for understanding the mechanical behavior of the system.
DSC measurements further enable the determination of critical thermal transitions of the glass, including the glass transition temperature, crystallization, and relaxation processes, which are essential for characterizing the viscous behavior of the residual glass. The integration of these techniques provides a comprehensive understanding of the role of residual glass in stress transfer and mechanical properties control within multicomponent ceramics.
This is a first insight on the characteristics of technologically relevant glasses for the production of porcelain and vitrified ceramic tiles. The approach here followed actually allows appreciating the effect of variations in the Na/K ratio and silica content that mirror what can occur in the industrial production. This paves the way for application in more complex materials and real industrial conditions.
Contribution of PNRR M4C2 - PRIN 2022PXHTXM - STONE project, funded from EU within the Next generation EU program. CUP: D53D23004840006
How to cite: Giordano, D., Cassetta, M., Conte, S., Zanelli, C., Molinari, C., Dondi, M., and La Felice, S.: Characterization of Residual Glass Evolution from Vitrified Ceramics: Insights from Raman Spectroscopy and DSC into Viscous and Elastic Properties, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8978, https://doi.org/10.5194/egusphere-egu25-8978, 2025.
EGU25-9505 | ECS | Posters virtual | VPS22
Characterisation of the heterogeneity of vesicular lava rocks from Fogo Volcano (Azores, Portugal) combining conventional laboratory methods with X-ray microtomographyTue, 29 Apr, 14:00–15:45 (CEST) | vP1.24
Experimental data on rock physical properties obtained through laboratory methods are enhanced by advanced techniques like X-ray microtomography (µCT) and image analysis. Lava rocks are important geological formations worldwide with varying textures, structures, and physical and mechanical behaviour. This research focuses on the heterogeneity analysis of vesicular lava rocks with intermediate composition from the Fogo Volcano (or Água de Pau Volcano, S. Miguel, Azores, Portugal). The effective porosity of six cubic samples is determined using the buoyancy technique. Ultrasonic wave velocities and capillarity absorption coefficient are obtained along three orthogonal directions using the through-transmission method and a European standard, respectively. Unconfined compressive strength (UCS) combined with µCT is determined in three cores from a single cube.
Results demonstrate that pore structure governs water uptake by capillarity and ultrasonic wave velocities. Regardless of the direction, the nonlinear water imbibition reflects a bimodal pore size distribution, confirmed through µCT imaging. The Sharp Front model describes this behaviour as the sum of two separate absorption processes related to larger (28.01-12.96 g/m2·s0.5) and finer (0.45-1.73 g/m2·s0.5) pores. Capillary-connected porosity (5.07%) is lower than connected porosity (18.5–20.1%) since gravitational fluid transport dominates for large pores (>1 mm). P-wave velocities (2802–3208 m/s) show minor dependence on pore shape, while Vp/Vs ratios (1.76 ± 0.25), dynamic Young’s modulus (16.78 ± 3.20 GPa), and Poisson’s ratio (0.23 ± 0.11) reflect vesicular textures.
µCT-based image analysis enables porosity quantification, revealing that effective porosity includes vesicles and pore-linking fractures. Permeability (0.7–6.6 mD) depends on tortuosity, which reduces fluid percolation despite higher connected porosity.
UCS (15.5-36 MPa) variations depend on pore size, orientation relative to the loading direction, and connected porosity, with minor influence from pore shape. µCT imaging reveals failure through tensile splitting, with fractures propagating from pore edges in all cores. The weakest specimen has more plagioclase phenocrysts, whose borders, intragranular cracks, and pores contribute to reduced strength.
These findings underscore the need to consider the heterogeneous pore structure of vesicular lavas when interpreting field measurements or improving volcano stability models. Advanced imaging and computational techniques clarify the role of vesicles and phenocrysts in strength and crack development patterns, providing important insights into the mechanics of lava rocks.
How to cite: Pereira, M. L., Cueto, N., Pappalardo, L., Buono, G., Falasconi, A., Moreira, M., Zanon, V., and Fernandes, I.: Characterisation of the heterogeneity of vesicular lava rocks from Fogo Volcano (Azores, Portugal) combining conventional laboratory methods with X-ray microtomography, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9505, https://doi.org/10.5194/egusphere-egu25-9505, 2025.
