PICO
Despite the crucial role of computational methods in integrating and interpreting data from various sources, there has been limited progress in establishing a dedicated community within volcanic and magmatic studies. This session aims to address this gap by focusing on computational approaches. We seek to bring together researchers working on forward and inverse modelling, machine learning, and other computational methods to foster a thriving community to complement well established observational and experimental communities.
We encourage contributions that explore the theory, application, and validation of computational approaches in the context of experimental and observational data. Topics of interest include, but are not limited to:
- Multiphase flow dynamics
- Thermodynamics and phase equilibria
- Magma transport and storage
- Chemical and rheological melt-rock interactions
- Crystallization and degassing processes
- Energy and mineral resource genesis
- Magma-hydrothermal interactions
- Eruption dynamics and hazards
This session aims to provide a platform for in-depth technical discussions that are challenging to facilitate in broader multidisciplinary sessions, ultimately fostering a stronger computational community within volcanic and magmatic studies.
We report a three-dimensional, two-phase thermal-chemical-fluid dynamical model and its application to explore the evolution of magma bodies. The model solves for velocity using a finite-element approach, and for transport using a control-volume scheme to ensure conservation of energy, mass and components. Solid and melt phases are modelled as Stokes fluids with very different Newtonian viscosities. Individual crystals in the solid matrix are incompressible, but the solid phase is compressible to account for changes in melt fraction. The formulation captures compaction and convection of the solid matrix, and flow of melt via a Darcy-type formulation at low melt fraction, and a hindered-settling type approach at high melt fraction. It also captures heat transport by conduction and advection, melt-solid phase change, and component transport and reaction. A chemical model is used to calculate phase fraction and composition. The numerical package sequentially solves for (1) melt and solid velocity (mass and momentum conservation); (2) enthalpy and component transport (energy and component conservation) and (3) phase fraction and composition (chemical model). Material properties such as density and viscosity are coupled to solution fields such as melt fraction and composition to yield a highly non-linear system of coupled equations which are solved iteratively.
We apply the code to investigate convection and melt segregation processes in a cooling magma body. Our findings suggest that convection is expected across a wide range of magma reservoir geometries, melt fraction and bulk composition. The rate of cooling and crystallization is a primary control on whether convection is observed, with thin bodies cooling and crystallizing before convection becomes established. In more slowly cooled bodies, convection and melt segregation interact to produce spatially complex and dynamically evolving variations in melt fraction and bulk composition, which often differ significantly from simple conceptual models that envisage accumulation of buoyant, evolved melt at the top of the reservoir and dense residual solid at the base. The transition between convecting- and non-convecting behaviour is also heavily influenced by the relationship between solid phase shear viscosity and melt fraction. The solid phase bulk viscosity, which is indistinguishable from shear viscosity in one-dimensional analysis, plays a key and distinct role in controlling the predicted magma reservoir dynamics.
How to cite: Hu, H., Salinas, P., and Jackson, M.: Convection, melt segregation and chemical differentiation in crustal magma reservoirs: Insights from 2- and 3D numerical models, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4711, https://doi.org/10.5194/egusphere-egu25-4711, 2025.
The East Eifel Volcanic Field (EEVF) in western Germany comprises numerous scoria cones, maars, and lava domes, with recent geodetic measurements revealing uplift rates of up to ~2 mm/yr. Deep low-frequency earthquakes indicate ongoing magmatic processes and transcrustal melt pathways. To refine the understanding of the geometry and volume of potential magmatic structure, we present a 3D gravity and magnetic inversion of the uppermost crust beneath the EEVF.
Initially, synthetic forward modeling evaluated the detectability of magma bodies of varying sizes and depths, considering realistic density and susceptibility contrasts. We then applied advanced gravity data processing methods—namely terracing and clustering—to highlight subtle anomalies and improve interpretability prior to inversion. The subsequent inversion of the Bouguer gravity anomaly and total magnetic intensity data employed a flexible regularization scheme that balances smoothness and compactness, enabling realistic imaging of magmatic accumulations. As potential-field data alone is non-unique, we plan to incorporate results from local earthquake tomography provided by the ongoing Large-N seismic experiment in the Eifel. Notably, preliminary tomographic results suggest a cylindrical anomaly approximately 3 km in diameter extending from near-surface to ~10 km depth beneath the Laacher See. These seismic constraints will help reduce ambiguity in the final model by offering well-resolved information at shallow to mid-crustal depths and correlating known structures in both gravity and tomography.
The resulting 3D model will illuminate the lateral and vertical extents of structures origination from magmatic processes beneath the EEVF, advancing our knowledge of its transcrustal magmatic system. This work will also inform future scientific drilling under the ICDP-EIFEL initiative, where new boreholes and monitoring efforts aim to clarify volcanic processes in this intraplate volcanic region.
How to cite: Sobh, M., Gabriel, G., Götze, H.-J., Strehlau, R., Fadel, I., Zhang, H., and Dahm, T.: Delineation of the geometries of magmatic structures beneath the East Eifel Volcanic Field (Germany) Using 3D Gravity and Magnetic Inversion, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6602, https://doi.org/10.5194/egusphere-egu25-6602, 2025.
The Changbaishan volcano (CBV) located on the border of China and North Korea, is one of the most dangerous active volcanoes on Earth. The CBV has experienced two “unrest periods” since 2000C.E. with uplift, increased 3He/4He ratio gas emissions and increased seismicity frequencies. During the intermediate “rest period”, subsidence occurred particularly on the eastern part of the Tianchi caldera. Whereas the magmatic system beneath the volcano is likely responsible for the surface deformation, several factors can significantly influence the surface deformation field such as the geometry, physical properties, and connection between separate magma or mush chambers. The mechanism of uplift surface at CBV is interpreted as magma recharge and the mechanism of subsidence is still under debate. Previous geophysical investigations and satellite data indicate that a shallow magma chamber might exist at 5 km depth, and the shallow magma chamber plays an important role in producing the surface deformation field. Understanding the magmatic system beneath CBV will improve the assessment of the risk of CBV.
Here, we utilized a new approach to construct a 3D thermo-mechanical model of the magmatic system beneath CBV developed on the basis of seismic velocity data collected during the “rest period”. We compare model output with InSAR data of the same period, to analyze the mechanism of the surface velocity field during the “rest period”. We test the influence of the shallow magma chamber at 5km, the connection of the magma system and physical properties of the magma chamber and surrounding host rock. Our results are consistent with there being four interconnected magma chambers beneath the CBV compared with InSAR observation. They support that a shallow magma chamber exists at 5km depth. This shallow magma chamber depth causes a convection field, and the convection field induced a downward flow at CBV area. Magma channels connecting the different magma batches play an important role in producing the uprise velocity to the surface. The higher temperature of the magma channels, the lower viscosity of the surrounding host rock and the higher density contrast with the surrounding host rock can increase the uprise velocity magnitude.
How to cite: Liu, H., Yang, J., zhao, L., Kaus, B., Spang, A., and Sun, B.: Numerical simulations of the influence of the magmatic system beneath Changbaishan volcano on surface deformation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16021, https://doi.org/10.5194/egusphere-egu25-16021, 2025.
Understanding how melt is extracted and makes its way toward volcanoes is a fundamental problem in magma dynamics. Geological observations of ophiolites show tabular dunite channels, which are commonly considered to be reactive channels for melt migration. The reaction-infiltration instability has been identified as an important mechanism responsible for the formation of these high-porosity melt channels in the upper mantle. To better understand this mechanism, we have extended previous linear analysis and performed non-linear numerical simulations in a compacting, chemically reactive porous medium.
Strong interactions between compaction and dissolution lead to two interesting unstable features: (1) high-porosity channels and (2) compaction-dissolution waves. The channeling instability that grows monotonically comes from the positive feedback between chemical reaction and melt percolation. The oscillatory compaction-dissolution waves show a checkerboard pattern that migrates upwards in the melting region, driven by the nonlinear feedback between compaction and reaction. These instabilities are controlled by two key dimensionless parameters: the stiffness, which characterizes the system's ability to compact, and the Damköhler number, which describes the relative importance of reaction to advection. The stiffness is strongly affected by the compaction length, which may either follow an inverse power-law dependence on porosity or only a weak dependence on porosity. Here we present a regime diagram with a range of stiffness and Damköhler number values and show that compaction-dissolution waves are favoured in systems with smaller compaction length and lower stiffness relative to high-porosity channels.
The parameter regimes predicted by linear theory align well with the non-linear numerical simulation results. Simulations also show strong interactions between melt channels and oscillatory waves, where the melt channels are focused in the upper domain and porosity waves are in the lower part. The relationships between high-porosity channels and compaction-dissolution waves in this study may shed new light on the geochemical and petrological observations related to magma migration in the mantle.
How to cite: Huang, M., Rudge, J., and Rees Jones, D.: Channels or waves: controls on melt migration through the upper mantle, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8875, https://doi.org/10.5194/egusphere-egu25-8875, 2025.
Owing to their abundance and relative availability on Earth's seafloor, mid-ocean ridge basalts (MORBs) have a well-defined chemical element budget, reflected by the low standard deviation associated with typical normal MORB (N-MORB) composition [1]. However, the exact mechanisms leading to magma differentiation and MORB generation remain debated, hindering our ability to evaluate MORB parental magma composition. In this study, we leverage the predictive power of the BDD21 numerical framework [2, 3] to obtain a representative trace element budget of parental MORB magma and assess its ability to fractionate into the N-MORB composition. Utilising revised parameterisations for mineralogy, melting, and partitioning, we couple BDD21 with numerical simulations of a MOR system driven by seafloor spreading in which we track the evolution of partial melting, mineral modal abundances, and concentrations of incompatible elements. Parental magma compositions are determined once simulations reach a steady state, and magma chamber replenishment models are employed to predict the trace element budget of the erupted liquid. We explore a range of geophysical and geochemical parameters to evaluate their effect on computed trace element concentrations and use the Bayesian inference framework BayesBay (https://github.com/fmagrini/bayes-bay) to invert for the set of parameters that best reproduces the N-MORB composition. Previous magma chamber replenishment models [4] are extended to account for multiple crystallisation events and melt-crystal interaction. Modelling outcomes suggest that petrologically constrained fractionation of parental magma compositions obtained through BDD21 yields glass compositions compatible with the N-MORB budget. Nevertheless, our results show a systematic underestimation of Sr concentration, indicating the presence of recycled oceanic crust in the MORB source region.
[1] Gale, A., Dalton, C. A., Langmuir, C. H., Su, Y., & Schilling, J. G. (2013). The mean composition of ocean ridge basalts. Geochemistry, Geophysics, Geosystems, 14(3), 489-518.
[2] Ball, P. W., Duvernay, T., & Davies, D. R. (2022). A coupled geochemical‐geodynamic approach for predicting mantle melting in space and time. Geochemistry, Geophysics, Geosystems, 23(4), e2022GC010421.
[3] Duvernay, T., Jiang, S., Ball, P. W., & Davies, D. R. (2024). Coupled geodynamical‐geochemical perspectives on the generation and composition of mid‐ocean ridge basalts. Geochemistry, Geophysics, Geosystems, 25(2), e2023GC011288.
[4] St C. O’Neill, H., & Jenner, F. E. (2012). The global pattern of trace-element distributions in ocean floor basalts. Nature, 491(7426), 698-704.
How to cite: Duvernay, T., Jiang, S., and Magrini, F.: Coupled Geodynamical-Geochemical Perspectives on the Generation and Composition of Mid-Ocean Ridge Basalts, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15139, https://doi.org/10.5194/egusphere-egu25-15139, 2025.
Simulating the chemical evolution of magmatic systems can be done with thermodynamic equilibrium modelling and recently developed melting models do quite a good job of predicting observations and reproducing experiments for a wide range of compositions. Yet, it remains a significant computational challenge as some of the most recent melting models include 11 oxides along with pressure and temperature, which makes this a 13-dimensional Gibbs energy optimisation problem. We recently developed the open-source parallel software package MAGEMin [1], along with an easy-to-use Julia interface (MAGEMin_C.jl [2]). Over the last year, we also developed a web-based graphical user interface, MAGEMinApp [3], with which users can easily compute pseudo-sections, do fractional crystallization experiments, or predict seismic velocities.
However, despite the progress, each point-wise thermodynamic calculation still takes 10-50 milliseconds (depending on the complexity of the system). This is too slow if one wishes to directly couple thermodynamic and thermo-mechanical simulations of the magmatic system, as those may require 1000’s-100’000s of calculations per timestep.
An alternative approach is to develop simplified parameterizations from the complete thermodynamic models (e.g., using machine learning tools). That, however, requires recalibration for different scenarios, and gives up some of the predictive power of the models, such as the chemistry of the stable mineral assemblage or seismic velocities, unless the system was trained on that.
We therefore developed a new approach in which we dynamically update a database of precomputed points that only performs new thermodynamic calculations for points that do not yet exist in the database. We only store the minimum required information per point, with which we can reconstruct all derived thermodynamic quantities without having to redo the minimization. This significantly reduces the computational effort and allows coupling thermodynamic simulations with thermo-mechanical simulations in a self-consistent manner. We illustrate the power of the method with 2D/3D thermo-kinematic simulations of magmatic systems, as well as by reactive two-phase flow calculations applied to small-scale magma transfer processes in lower crustal migmatites.
[1] https://github.com/ComputationalThermodynamics/MAGEMin
[2] https://github.com/ComputationalThermodynamics/MAGEMin_C.jl
[3] https://github.com/ComputationalThermodynamics/MAGEMinApp.jl
How to cite: Kaus, B., Riel, N., Dominguez, H., Frasunkiewicz, J., Aellig, P., and Moulas, E.: Fully coupled petrological/thermo-mechanical models of magmatic systems, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8624, https://doi.org/10.5194/egusphere-egu25-8624, 2025.
The modern view of magmatic systems includes transport and storage of melt at depths within the solid crust. An important process that directly controls the thermo-physical properties of magmatic systems is the chemical differentiation of the melt. Calculating the thermodynamic properties of the melt during its transport through the system is a well-known computational bottleneck in most multi-phase transport algorithms.
We present a Multi-Layer-Perceptron (MLP) surrogate model for fast prediction of thermodynamic properties of silicate melts in arc settings. The MLP takes a bulk rock composition of nine major oxides (SiO2-Al2O3-CaO-MgO-FeO-TiO2-NaO-K2O-H2O), temperature, and pressure as input variables and returns the melt fraction, composition, as well as the melt and system density. The surrogate model’s ability to predict thermodynamic properties is tested for data it has not seen during the training process. Results indicate that the MLP generalizes well within the range of the database. The melt fraction and components (i.e., major oxide concentration in the melt) are predicted with a root-mean square error (RMSE) of less than 1 wt-% and the densities with an average RMSE of ca. 5 kg/m3.
The synthetic data set for training and testing the model has been generated with MAGEMin, a parallelized Gibbs energy minimization software (Riel et al., 2022). MAGEMin features adaptive mesh refinement (AMR) capabilities. This functionality allows for high resolution phase diagrams at important reaction lines with a minimum amount of computational points. Our synthetic database consists of 360’000 MAGEMin minimization points. As input parameters to MAGEMin we used anhydrous compositions from arc settings provided by the GEOROC database (Lehnert et al., 2000) varying 43-60 wt-% SiO2 and a pressure-temperature range of 650-1000°C and 1.0-10.0 kbar.
Predicting melt properties with the surrogate model is a point-wise operation which takes only a fraction of a second for hundreds of thousands of points. This functionality opens the door for accelerating mineral equilibria calculations within the framework of high-performance computing transport algorithms. We discuss possible application of the surrogate model within the framework of modern geodynamic algorithm architectures.
References:
Lehnert, K., Su, Y., Langmuir, C. H., Sarbas, B., & Nohl, U. (2000). A global geochemical database structure for rocks. Geochemistry, Geophysics, Geosystems, 1(5).
Riel, N., Kaus, B. J., Green, E. C. R., & Berlie, N. (2022). MAGEMin, an efficient Gibbs energy minimizer: application to igneous systems. Geochemistry, Geophysics, Geosystems, 23(7), e2022GC010427.
How to cite: Candioti, L. G., Nathwani, C. L., and Chelle-Michou, C.: A neural network-based surrogate model to accelerate mineral phase equilibria calculations for silicate melts in arc settings, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8644, https://doi.org/10.5194/egusphere-egu25-8644, 2025.
Deciphering magmatic system dynamics is inherently challenging due to the lack of direct observations of subsurface processes. Numerical modelling serves as a key tool to interpret indirect evidence from petrological and geochemical analyses of igneous rocks. At the heart of magma dynamics lies the interplay between complex multiphase fluid mechanics and multicomponent thermochemistry. Accurate modelling of these systems requires determining stable phase assemblages, which involves computationally demanding Gibbs free energy minimisation across high-dimensional compositional spaces with dozens of end-members. Current algorithms often lack the robustness and efficiency required for real-time integration into coupled thermos-chemical-mechanical models.
Traditional approaches to coupled modelling have frequently employed highly simplified phase relationships, such as single-phase loops, or relied on precomputed lookup tables to avoid the computational cost of real-time phase equilibrium calculations. These methods, however, impose significant limitations. This work introduces an alternative—a petrological model that generates multi-dimensional pseudo-phase diagrams in P-T-X space using pseudo-component end-members. Inspired by ideal solution thermodynamics, this approach eliminates the need for computationally expensive energy minimisation, overly simplistic phase representations, or cumbersome lookup tables. Instead, it employs a computationally efficient Newton method to solve a constrained nonlinear system.
Calibration of the model using standard machine learning techniques allows it to closely approximate key petrological trends, such as fractional crystallisation, observed in experimental data and full thermodynamic calculations. Once calibrated, the model efficiently tracks the dynamic evolution of major mineral and melt phases, including their compositions, across extensive P-T-X ranges. The calibration process further identifies the principal axes of variability, typically reducing the system to 5-6 dominant pseudo-components associated with major liquidus phases. This dimensional reduction significantly simplifies the system’s complexity compared to full thermodynamic models while retaining essential petrological insights.
How to cite: Keller, T.: Efficient Modelling of Magmatic Systems: A Pseudo-Component Approach to Phase Equilibria in Coupled Simulations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18794, https://doi.org/10.5194/egusphere-egu25-18794, 2025.
Magnetite-apatite (MtAp) deposits, also known as iron-oxide-apatite or Kiruna-type deposits, are critical sources of high-grade iron ore and rare earth elements (REE), essential for industrial applications and the global transition to green energy. The formation of MtAp deposits is commonly attributed to the immiscibility between iron oxide phosphate liquids and silicate magma (FeP–Si). Recent studies have shown that light rare earth elements preferentially partition into the iron-phosphorus melt, explaining the enrichment of light rare earth elements in MtAp deposits. While there is good evidence of an origin involving sub-volcanic intrusion to volcanic extrusion of an Fe-enriched orthomagmatic melt, the exact formation mechanisms remain controversial.
This study focuses on the El Laco deposit in northern Chile, adopting the hypothesis that spontaneous magma unmixing has indeed occurred within an El Laco-type subvolcanic magma body. The research aims to explore the formation mechanisms of magnetite-apatite (MtAp) deposits by investigating the role of iron-rich magmatic melts. Using a one-dimensional (1D) three-phase mechanical model based on existing theoretical frameworks, we simulated the separation and accumulation of immiscible iron-rich melts within an increasingly crystalline parent magma. The model reproduces the previously proposed transition from droplet settling to porous drainage mode and quantifies the relative efficiency of both modes of phase separation. We also perform a scaling analysis to define porous, mush, and suspension flow regimes and construct a regime diagram for three-phase flow. The results show that the separation efficiency of immiscible iron-rich melts reaches its maximum under intermediate crystallinity conditions. Furthermore, the model-derived accumulation rate of iron-rich melts can be used to estimate the time required to accumulate immiscible melt sufficient to form magnetite deposits of a given scale. Our findings support the physical viability of the liquid immiscibility hypothesis in the genesis of MtAp deposits and provide new insights into the formation mechanisms of other valuable deposits associated with immiscible melts, such as the segregation of Ni-Cu-Co-enriched sulphide melts in orthomagmatic Cu-Ni-sulphide deposits and metal-enriched magmatic brines in porphyry copper systems.
How to cite: Chai, T. and Keller, T.: Three-phase flow modelling of immiscible melt segregation in the genesis of magnetite-apatite deposits, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18413, https://doi.org/10.5194/egusphere-egu25-18413, 2025.
The volcanic rocks belonging to the Maden Complex are observed along the Southeastern Anatolian Orogenic Belt, and the study area covers the surroundings of Malatya (Türkiye). The Eocene (?) Maden Complex are represented by basalt and diabase dykes cutting them. The studied rocks have high Mg# (51.7-92) values. With increasing Zr ratios, positive trends are observed in CaO, TiO2, Fe2O3, Ba and Sr values, and negative trends are observed in MgO, Al2O3, Ni, and Co values. Positive trends in CaO and Sr values indicate the effect of plagioclases in fractional crystallization. Trends in TiO2, Ni and Fe2O3 values indicate fractional crystallization of olivine, pyroxene and Fe-Ti oxides. The Maden Complex have relatively low La/Yb (1.16-6.69) and Nb/La (0.20-1.45) ratios, indicating a lithospheric mantle/lithospheric-asthenospheric mantle origin. In the primitive mantle-normalised multi-element diagram, negative trends are observed in Rb, P, Nb and Ti elements, and positive trends in Sr and Ba values of the rocks belonging to the Maden Complex. A nearly horizontal trend is observed in the chondrite-normalised multi-element diagram. The LaN/LuN (LREE/HREE) ratios among the light rare earth elements (LREE) and heavy rare earth elements (HREE) of the studied volcanic rocks range from 0.79 to 4.76, showing weak to moderate fractionation. The basalts and diabases belonging to the Maden Complex show insignificant negative Eu anomalies, and the Eu/Eu* values vary between 0.81 and 1.06. The Dy/Yb ratios of the studied volcanic rock samples vary between 1.49 and 1.87. These ratios indicate that these rocks were derived from a spinel-bearing lherzolite source representing shallow depths. Mineral chemistry analyses were performed on pyroxene and plagioclase minerals in the studied volcanic rocks. According to pyroxene minerals, the temperature (T) and pressure (P) values of the rocks vary in the range of (1194-1442) and (2.8-20), respectively. According to plagioclase minerals, the T and P values vary between (945-1049) and (26.6-55.7).
The 87Sr/86Sr(i) values of the studied volcanic rocks vary between 0.703514 and 0.704958, 143Nd/144Nd(i) values vary between 0.512861 and 0.512897, and they exhibit a sequence close to the MORB field in the 87Sr/86Sr(i) versus 143Nd/144Nd(i) variation diagram. ƐNd(t) values range from 5.6 to 6.3, and TDM(Ga) values vary between 0.45 and 0.83. 206Pb/204Pb(i) values vary between 18.42267 and 19.39642, 207Pb/204Pb(i) values vary from 15.54136 to 15.62174, 208Pb/204Pb(i) values range from 38.40535 to 39.04312. The 207Pb/204Pb(i) diagram versus 206Pb/204Pb(i) also shows a sequence close to the MORB field. In light of all data, it is thought that the volcanic rocks of the Maden Complex are derived from a magma source representing shallow depths of MORB origin. This study was supported by the TUBITAK project numbered 123Y070.
Key Words; Geochemistry, Maden Complex, Mineral chemistry, Sr-Nd-Pb isotopes
How to cite: Sar, A., Rizeli, M. E., Ertürk, M. A., and Yılmaz, İ.: Petrogenesis of the Maden Complex Volcanic Rocks in the Southeastern Anatolian Orogenic Belt (Malatya- Eastern Türkiye): insight from whole-rock geochemistry, mineral chemistry, and Sr-Nd-Pb isotopes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8091, https://doi.org/10.5194/egusphere-egu25-8091, 2025.
The Guleman ophiolite is a part of the Southeast Anatolian Orogenic Belt (SAOB) ophiolites. The Guleman ophiolite, which is located to the northeast of Maden and covers an area of 200 square km east of the Hazar Lake, is situated 50 km southeast of Elazığ, and it is one of the important ophiolitic massifs in the SAOB. The Guleman ophiolite formed in the southern branch of the Neo-Tethys ocean and was emplaced beneath the Anatolide-Tauride platform. It is usually in tectonic contact with the other units, and some of it has been intruded by Late Cretaceous granitic rocks and is covered by younger sediments. The Guleman Ophiolite is composed of serpentinised mantle tectonites, ultramafic-mafic cumulates, isolated gabbro and sheeted (diabasic) dykes. The mantle section of Guleman ophiolite mainly consists of serpentinised harzburgites and dunites with significant, economically level podiform chromitites. The serpentinised mantle peridotites consist of relicts of olivine and orthopyroxene, serpentine minerals and Cr-spinel ± carbonate minerals. Petrographic study of serpentinised peridotites shows that the rocks consist predominantly of lizardite and portlandite serpentines and olivine and have the opaque mineral assemblage of magnesioferrite+spinel developed during serpentinisation of the rock. Carbonate-bearing veins were observed in the serpentinite. The typical pseudomorphic textures consist of meshes and bastites. There are two types of alteration mineralogy and textural relationships. Firstly, lizardite mesh-textured vein networks with relict olivine cores, and secondly, bastite texture with serpentinisation of orthopyroxene. Mesh-textured serpentine veins with fresh olivine cores occur in all samples, while bastite texture occurs in harzburgite samples. The XRD pattern shows that the main constituents of the sample were the lizardite (Mg3(Si2O5)(OH)4) and portlandite (the calcium analogue of brucite) Ca(OH)2 minerals, which have various microstructure features. This study was supported by the TUBITAK project numbered 124Y011.
Key Words: Guleman Ophiolite, Serpantinisation, Petrography, XRD, Türkiye
How to cite: Ertürk, M. A., Rizeli, M. E., Sar, A., Beyarslan, M., and Aysal, N.: Serpentinisation of Guleman Ophiolite in the Southeast Anatolian Orogenic Belt (Türkiye) , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8093, https://doi.org/10.5194/egusphere-egu25-8093, 2025.
