Since its establishment in 1963, the International Heat Flow Commission (IHFC) has fostering and curating the Global Heat Flow Database (GHFDB). The dynamic nature of techniques and methodologies used in heat-flow density determination has necessitated regular updates to the database. Despite its widespread utility, the GHFDB faces challenges arising from variations in measurement techniques and data quality. Ongoing efforts are dedicated to overcoming these challenges, aiming to elevate the database's accuracy and reliability, thus solidifying its value within the scientific community. Multiple iterations of the GHFDB exist, primarily focused on characterizing the quality of individual heat-flow data points. However, the establishment of a new, authenticated GHFDB demanded the development of a fresh reporting standards for heat-flow data submitted to the IHFC. This new framework, derived from a collaborative global initiative, incorporates 62 metadata fields. This comprehensive approach became imperative due to the escalating volume of data and the diverse methodologies employed, necessitating a standardized scheme to evaluate the quality of heat-flow density determinations consistently. This update provides insights into the community-driven initiative initiated in 2021, targeting the reassessment of approximately 1,414 publications containing 73,033 global heat-flow data points. A noteworthy aspect of this initiative is the introduction of a novel quality scheme, unifying three independent criteria into a combined score. This score encompasses quantified uncertainty, methodological quality, and the status of overruling effects. The integration of these criteria facilitates a swift comparison of heat-flow data, instantly revealing any missing data or inadequately documented information. The introduction of this quality scheme empowers users to efficiently select reliable heat-flow values tailored to their specific research purposes.

How to cite: Neumann, F., Fuchs, S., Norden, B., Balkan-Pazvantoğlu, E., Petrunin, A., Elbarbary, S., Jennings, S., Elger, K., Frenzel, S., Ott, N., Maes, S., and Data Assessment Group, G. H. F.: The heat flow data assessment project: Transformation of the global heat flow database, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16952, https://doi.org/10.5194/egusphere-egu24-16952, 2024.

Terrestrial heat-flow determinations are crucial for understanding the thermal structure of the lithosphere. This study presents the results of a revision of the heat flow database in Türkiye contributing to the Global Heat Flow Data Assessment Project conducted by the International Heat Flow Commission (IHFC). The database includes 750 heat flow determinations reported in Türkiye between 1991 and 2023, and are reassessed according to the new IHFC specific structure documented by Fuchs et al. (2023). The data are gathered from the original literature and examined to ensure complete documentation of relevant metadata. The quality score is assigned based on the uncertainty, methodology and environmental disturbances. The new national wide database shows that heat-flow determinations are predominantly distributed in the western part of the country. However, the eastern part of the country has been poorly investigated to date. Despite numerous exploration-based studies conducted in the region concerning its substantial geothermal potential, a noteworthy portion of thermal data remains archived and is not accessible. The study reveals a significant demand for additional heat flow determinations to allow the drawing of a substantially revised and robust heat-flow map. However, the ongoing update of the Türkiye Heat Flow Database already allows a more transparent identification of areas with thermal anomalies.

How to cite: Balkan-Pazvantoglu, E., Neumann, F., Norden, B., and Fuchs, S.: Assessment of the Türkiye Heat Flow Database 2023, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16175, https://doi.org/10.5194/egusphere-egu24-16175, 2024.

Sedimentary processes govern fluid-flow heterogeneities in porous media in several scales, therefore, their understanding is a common practice in the petroleum industry. However, hydrogeologists have lagged behind when it comes to discretising porous sedimentary aquifers in flow, heat and transport models. At the Upper Rhine Graben, in Eastern France, the Lower Triassic Buntsandstein Group serves as an important reservoir for groundwater and lithium-rich geothermal brines. The main objective of this study is to assess the architecture of the Lower Grès Vosgien Formation (LGV), Middle Buntsandstein, and how sedimentological processes, at different scales, generate significant permeability heterogeneities. It is implemented a high-resolution sedimentological characterisation, through vertical profile descriptions, digital outcrop model, and petrographic analysis. Subsequently, permeability measurements are coupled with sedimentological data, to identify different scales of sedimentary controls on permeability distribution. Finally, a realistic 2D hydrostratigraphic conceptual model is generated as a reference, allowing the evaluation of how different scenarios of heterogeneity simplification impact fluid-flow modelling, concerning particle residence time, macro-dispersivity, and upscaled anisotropy.

Results indicate that 93% of the LGV is composed of sandstones deposited by a braided fluvial system, with evidence suggesting that discharge variability was a main depositional controlling factor of sedimentary facies and heterogeneity distribution. The LGV stacking pattern reveals periods when fluvial processes were absent, and aeolian processes dominated sediment transport and deposition, comprising 7% of the total LGV thickness. The aeolian deposits record signs of persistent water in the system, either due to water table rise, or ephemeral floods, primarily contributing to the sedimentary facies association with the lowest permeabilities of the LGV, exceeding 3 orders of magnitude lower than the fluvial deposits. Despite representing only 7% of the LGV total thickness, the aeolian deposits exhibit lateral extensions that extrapolate outcrop scales (hundreds of metres), representing significant vertical flow baffle zones.

Fluid-flow simulations demonstrate that model simplifications, whether through assigning deterministic permeability values (mean), or stochastically distributing permeabilities, unconstrained by realistic sedimentary architectures, have a direct impact on macro-dispersivity (both vertical and horizontal), vertical mean residence time, and upscaled anisotropy results. Nevertheless, the results for horizontal mean residence time show no significant effect when simplifying the observed sandstone heterogeneities.

How to cite: Medeiros Bofill, L., Schäfer, G., Bozetti, G., Schuster, M., Ghienne, J.-F., Ackerer, P., Scherer, C., Souza, E., and Armelenti, G.: Sedimentological control on permeability heterogeneity, and its effects in fluid-flow modelling: a case study of the Middle Buntsandstein sandstones, Upper Rhine Graben, Eastern France, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10134, https://doi.org/10.5194/egusphere-egu24-10134, 2024.

During the late stages of the Variscan orogeny, generalized gravitational collapse with coeval magmatism took place in the Central Iberian Zone, in Iberia. This event is getting the attention of the scientific community due to its likely role in the generation of strategic mineral resources (i.e. Sn, W, Nb, Ta, Sc, Au, Sb). In this regard, to study how the Variscan orogenic architecture controls the generation of mineral deposits the GOLDFINGER project was born. As part of the project, the Martinamor gneissic dome (Salamanca), which presents several mineral deposits, was covered by 31 short-period (2 Hz) 3-component seismic stations. Through applying techniques of ambient noise seismic interferometry, we have constructed a 3D S-wave velocity model of the extensional dome, allowing us to extend in depth the geometry of igneous rocks, their host rocks, and some of the structures. Among the most relevant results, we have identified the depth configuration of a granitic body outcropping discontinuously east of the study area, and whose upper boundary has been interpreted as the extensional dome detachment level. This structure may have provided a pathway for mineralizing fluids. This work demonstrates that the seismic noise interferometry technique has sufficient resolution to interpret medium-scale structures and to discern different lithologies with moderately contrasted physical properties.

Funding: grant PID2020-117332GB-C21 funded by MCIN/ AEI /10.13039/501100011033; EIT-Raw Materials project 17024 (SIT4ME: Seismic Imaging Techniques for Mineral Exploration); SA084P20 from the JCyL government, and TED2021-130440B-I00 funded by MCIN/AEI/10.13039/501100011033 and European Union NextGenerationEU/PRTR.

How to cite: Palomeras, I., Ayarza, P., Gomez-Barreiro, J., Martí, D., Martínez-Catalán, J. R., Sánchez-Sánchez, Y., Dos Santos, K., Yenes, M., Pérez-Cáceres, I., Barrios, S., Élez, J., and DeFelipe, I.: Imagining the Deep Structure of a Mineralized Extensional Dome in the Variscan Central Iberian Zone (Spain) using Ambient Noise Seismic Data., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7869, https://doi.org/10.5194/egusphere-egu24-7869, 2024.

Seafloor massive sulfide (MS) deposits on oceanic spreading centers have variable concentrations of base metals (mostly Cu, Zn), precious metals (Au, Ag), critical metals (Co, Ni), and other trace elements. The geological factors that control this geochemical variability are still a matter of debate. In particular, the role of the composition of substrate rocks (specifically mafic vs. ultramafic) has been variably considered to be decisive or subordinate. In a previous study (Toffolo et al., 2020, Earth Sci. Rev.), we have investigated these factors by means of robust principal component and factor analysis of chemical data for MS samples from mid-ocean ridges worldwide. We found that a large part of the observed variability is produced by a combination of three independent factors, interpreted to reflect (in order of importance): (1) the temperature of deposition, which controls the relative enrichments in (Cu, Se, Co) vs. (Pb, Sb, Zn, Ag), (2) the ridge spreading rate, which influences the oceanic basement structure and the rock-to-water ratios, leading to opposite behaviors of (Au, Ag) vs. Ni, and (3) zone refining. Unexpectedly, the composition of the substrate did not emerge as a statistically significant independent factor. An important limit of our previous investigation was that literature data were often incomplete, thus limiting the number of samples and of chemical elements for the multivariate statistical analysis. We have now addressed this problem by using statistical imputation techniques and by integrating the database with additional literature and in-house data for present-day deposits on mid-ocean ridges and ancient deposits in ophiolites from different settings (supra-subduction-zone, mid-ocean ridge, ocean-continent transition). As a result, undersampling of ultramafic-hosted deposits was significantly reduced and the number of elements was raised to 11, including Cu, Zn, Pb, Au, Ag, Co, Ni, Se, Sb, Mo and the previously excluded As. The integrated database essentially confirms our previous findings. In addition, deposits in supra-subduction-zone ophiolites show factor scores typical of high deposition temperatures and high rock-to-water ratios, consistent with their formation on infant-arc, slow-spreading centers. The potential influence of other local geological factors will be discussed.

How to cite: Nimis, P., Aminizadkovij, N., Meyzen, C., Toffolo, L., Melekestseva, I., Paccagnella, O., and Patten, C.: Multivariate statistical analysis of mafic- and ultramafic-hosted seafloor massive sulfides, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11471, https://doi.org/10.5194/egusphere-egu24-11471, 2024.

The Caledonian-Appalachian Belt (CAB) hosts several economic and sub-economic polymetallic vein systems and is, therefore, an excellent natural laboratory to study the variations in the characteristics of ore deposit and the timing of their formation, within an orogenic belt. We present some of the preliminary outcomes of a large-scale study on the variability of the vein-hosted mineralisation within the CAB, covering c. 20 different polymetallic vein systems within the Grampian Terrane and its equivalents in Scotland, Northern Ireland, Ireland and Newfoundland.

The multi-disciplinary study combines structural data, age determinations, vein textural mapping and paragenetic interpretation, gold geochemical characterisation, and stable isotope data to show that although the occurrences show many superficial structural and mineralogical similarities, there are significant differences between the structural styles, mineralogy and timing of the mineralisation in different areas (see [1] and [2] for the first publications coming from this work). At least three, possibly four, distinct mineralisation stages are identified between Ordovician and Early Devonian, each associated with a characteristic structural style that can be linked to the overall tectonic evolution of the Grampian Terrane. The tectonic evolution of the orogen in time and space therefore greatly influenced both the timing and the style of mineralisation.

References:

[1] Shaw J, Torvela T, Cooper M, Leslie G, Chapman R (2022). A progressive model for the Cavancaw Au-Ag-Pb vein deposit, Northern Ireland, and implications to the metallogeny and evolution of the Grampian Terrane. J. Struct. Geol. 161, https://doi.org/10.1016/j.jsg.2022.104637.

[2] Chapman R., Torvela T, Savastano L (2023).  Insights into regional metallogeny from detailed compositional studies of alluvial gold: An example from the Loch Tay area, central Scotland. Minerals 13, doi.org/10.3390/min13020140.

How to cite: Torvela, T., Chapman, R., Shaw, J., Manuc, G., and Savastano, L.: Relationships between the tectonic evolution of an orogen and the formation of polymetallic vein deposits , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9006, https://doi.org/10.5194/egusphere-egu24-9006, 2024.

There are two sets of petroliferous strata developed in the Huoshiling Formation volcano in the Longfengshan area of the Changling fault Depression. The oil and gas have the characteristics of "near source gas, far source oil rich", the abundance of oil and gas decreases from the depression zone to the western tectonic belt, and is enriched in the top and middle of volcanic rocks in longitudinal direction, and widely distributed along faults in plane. In this paper, the controlling factors of hydrocarbon distribution in volcanic rocks are discussed from the perspectives of source rock development condition, reservoir physical property and transport condition by means of seismic, well logging and geochemical data, cores and microsections observation, CT scanning and inclusion analysis. The results show that the oil and gas distribution in the volcanic rock mass in Longfengshan area is mainly affected by the following factors: the thermal evolution degree of the source rock controls the oil and gas phase distribution, and the source and reservoir configuration determines the oil and gas capture probability; The distribution characteristics of high-quality volcanic rock reservoir can control the distribution range of oil and gas, and the vertical development difference of primary, secondary dissolution and fracture high-quality reservoirs determines the vertical accumulation of oil and gas. The fault and unconformity control the migration of oil and gas from the depression zone to the slope zone and the western tectonic zone, and its transport performance and the micro-transport structure of internal fractures ultimately determine the location of oil and gas accumulation. The distribution of overlying layers in and above volcanic rocks, the type of reservoir-cap combination and the configuration of broken cap prevent the oil and gas loss and control the oil and gas enrichment horizon. Based on the differences of main controlling factors of hydrocarbon accumulation in volcanic rocks, the effective source rock thickness, volcanic reservoir physical properties, reservoir-cap combination characteristics and transport conditions are taken as indicators to evaluate the hydrocarbon charging capacity of volcanic rocks, and the measured values of the above factors are divided into several intervals. According to the distribution range of the evaluation index, each interval is evaluated. Finally, according to the calculation results of the established oil and gas charging capacity evaluation formula, the evaluation results have a good correspondence with the current oil and gas distribution, and the results have certain guiding significance for determining the direction of oil and gas exploration in the later period.

How to cite: Hou, S. and Jiang, Y.: Main controlling factors of volcanic oil and gas distribution and charging capacity evaluation of Huoshiling Formation in Longfengshan area, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4824, https://doi.org/10.5194/egusphere-egu24-4824, 2024.

Natural hydrogen, emerging as a clean and abundant energy source, holds significant promise for advancing sustainable energy solutions. Its production offers a carbon-neutral alternative to fossil fuels, aligning with global efforts to mitigate climate change. This research focuses on developing a methodology to estimate the rates of natural hydrogen generation in serpentinization areas; in this case a local area in Eastern Morocco. It employs a multilevel approach that encompasses the modeling and analysis of the surface, near-surface, and deep components of the natural hydrogen system. At the surface level, potential hydrogen seeps are identified as semi-circular structures and surface faults are examined using high-resolution geophysical data. For the near-surface component or seal of the potential reservoir, which can extend thousands of meters deep, a full 3D geological model is constructed. The deep component, representing the source rock, is analyzed through the inversion of potential field data. These inversion results allow estimating the degree of serpentinization of the rocks, their volumes, and the affected surfaces. Subsequently, these volumes of rock are compared with temperature estimates to determine which part of the rock is capable of generating hydrogen. Laboratory-based hydrogen generation values from rock samples are then scaled up to the model, facilitating the calculation of hydrogen generation rates from the detected ultramafic rocks.

How to cite: Christiansen, R., Sobh, M., and Gabriel, G.: Assessing Natural Hydrogen Generation in Serpentinization Environments: A Workflow Based on a Comprehensive Case Study Analysis from the HyAfrica Project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7674, https://doi.org/10.5194/egusphere-egu24-7674, 2024.

Extensive lacustrine carbonate-rich shale intervals including upper fourth member (Es4s shale) and lower third member (Es3x shale) of the Paleogene Shahejie Formation have been deposited in the Boxing Sag, Dongying depression, Bohai Bay Basin, East China. These two representative shale members are considered to be good exploration prospects in the study area. In order to clarify the diagenetic process and exploration significance of sparry calcite in lacustrine calcareous shales, we take calcareous shale in Es4s to Es3x members in Boxing Sag as the research object, By means of thin section identification method, EDS line scan, Scanning Electron Microscopy, Fluid Inclusion Analysis, carbon and oxygen isotope and other methods, sparry calcite is classified, and then the genesis and diagenetic fluid of various types of sparry calcite are studied, so as to clarify the formation mechanism of sparry calcite, and finally discuss the influence of sparry calcite on reservoir. Finally, the influence of sparry calcite on the development of reservoir pores was discussed. The results show that the types of sparry calcite in the study area include granular calcite, porphyritic calcite and fibrous calcite, which are mainly caused by biological oxidation and thermal evolution of organic matter. Biogenic calcite has the characteristics of rich Mg and δ¹³C, and the organic matter makes the crystal more enriched with Fe and deficient δ¹³C. The formation of three kinds of sparry calcite has different effects on pore development, which is probably beneficial to improve reservoir physical properties.

How to cite: Sheng, K.: Early Diagenesis In Carbonate Sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2426, https://doi.org/10.5194/egusphere-egu24-2426, 2024.