Geological Framework Research Articles

Recent and active faulting along the exposed front of the Northern Apennines (Italy): New insights from field and geochronological constraints

Establishing genetic links between active shallow faulting and deep seismogenic sources is challenging, especially in areas where seismogenic faults lack clear and readily interpretable geological evidence at the surface. The architecture of the Pedeapenninic margin of the Northern Apennines (Italy) reflects a regional-scale and complex NE-verging blind thrust system, which is dissected by transpressive/transtensive faults resulting from active NE-SW orogenic compression. The local geological framework is defined by allochthonous ocean-derived units resting atop Pliocene-to-present successions exposed along the Northern Apennines margin and to the NE of it, while the innermost chain sector mostly contains Adria-related units. We present results from field structural-geological investigations to identify and characterize potential active faults along the margin. There, the Pliocene-to-present units are faulted and folded, indicating that tectonic activity is still on-going, thus contributing to the local seismic hazard. Top-to-the NE and SW normal faults are common in the area and deform the Pliocene-to-present succession together with NE-SW strike-slip and transpressional/transtensional faults. Based on field evidence, we define four potentially active thrust segments affecting Middle Pleistocene to Holocene deposits exposed along the margin. Calcite U-Th dating on samples from faults extend the most recent datable tectonic activity back to the Middle Pleistocene. Paleostress analysis from inversion of fault-slip data from the most recent identified striated fault planes constrains a NE-SW shortening direction parallel to the Apennines regional migration direction. A distinct but coaxial extensional stress regime, recorded by structures measured within Plio-Pleistocene formations, was also identified. Our results offer a sound starting point for future investigations aimed at improving our understanding of active and seismogenic faulting in the area, so as to create robust Probabilistic Seismic and Fault Displacement Hazard Assessment (PSHA and PFDHA) models that can implement refined seismic hazard maps benefitting from structural-geological deterministic inputs in addition to the classic seismological constraints.

Geological and Structural Framework, Inventory, and Quantitative Assessment of Geodiversity: The Case Study of the Lake Faro and Lake Ganzirri Global Geosites (Italy)

The geoconservation policies assumed by the Sicilian Region (Italy) induced to classify as geosites all the geodiversity preserved in the Sicilian natural reserves. In particular, two of these geosites present in the oriented natural reserve of the coastal lagoon of Cape Peloro (Messina, NE Sicily, Italy), denoted “Morpho–tectonic system of Cape Peloro–Lake Faro” and “Morpho–tectonic system of Cape Peloro–Lake Ganzirri”, were considered Global areal geosites on the base of their tectonic origin. Lacking an official scientific report of these sites, the present research was aimed to investigate the lagoon, in order to provide the (i) geological and structural framework, (ii) inventory, and (iii) quantitative assessment of geodiversity. The study geosites resulted to be originated during the post–Wurmian sea–level rise and the strong extensional tectonics affecting the Calabria–Peloritani Arc still active. Indeed, the lagoon depression hosting the Lakes Faro and Ganzirri, developed on low-relief coasts because of different systems of capable faults, NW–SE oriented in the Lake Faro and ENE–WSW oriented in the Lake Ganzirri. The quantitative assessment of geodiversity indicated high scores for the scientific value and the potential educational and touristic uses. On the basis of these results, it was possible to confirm the attribution of Lake Faro’s and Lake Ganzirri’s geodiversity to Global areal geosites, being the study morpho-structures key localities, providing indicators of representativeness, geological diversity, and rarity that ought to be protected as clear and unequivocal examples of the Earth’s geological history and evolution of the Quaternary tectonic coastal lagoons. Actual criticisms that could irreversibly affect the environmental equilibria have been evidenced. Possible actions for the redevelopment of the oriented natural reserve of the coastal lagoon of Cape Peloro and the extension of the geosites were also described.

The influence of supervised and unsupervised methods in the analysis of low density stream sediments in the regional prospecting of pegmatites in the state of Espírito Santo, Araçuaí Orogen - Eastern Pegmatite Province of Brazil

The state of Espírito Santo is located in Brazil southeastern and it is geologically inserted in the Eastern Brazilian Pegmatite Province in the Araçuaí Orogen. This province is one of the most important pegmatite provinces in the world, known mainly for the occurrence of gem-quality minerals and high grade lithium deposits. Although Espírito Santo has a geological framework with many granite intrusions similar to those hosting mineralized pegmatites in Minas Gerais, it hasn't been acknowledged as a potential pegmatitic area. There are reports of mineralization of beryl (aquamarine), topaz, amethyst, and chrysoberyl in the state's mineral history. I this research we use regional stream sediment geochemical data of the Espirito Santo State, to create prospective geochemical maps to map gemological pegmatites. To do so, primary descriptive statistical analyses as well as Pearson and Spearman correlations and Principal Component Analysis (PCA) were used to select elements associated with pegmatites. The geochemical prospectivity mapping was carried out by supervised and unsupervised approaches. The supervised method was based on integration of the elements by C-A fractal models, used to define the geochemical thresholds, and fuzzy logic methodology to integrate weighted geochemical maps. The unsupervised approach, however, was based on interpolation of the representative principal component scores. All models were validated using the Prediction Area plot (P-A plot). The results of our research showed that unsupervised methodology overperformed the other weighted supervised models, with a prediction rate of 78.14 % and prospectivity of 0.87. The final results also show a pegmatite prospectivity map for the Espirito Santo state, that indicates a great exploration potential for gemological minerals.)

Delineation of deep-seated crustal structures from magnetic data in the southeastern part of the Niger Delta basin, Nigeria

Regional magnetic data in the southeastern segment of the Nigerian Niger Delta were evaluated with the aim of mapping deep-seated tectonic elements. Enhanced filtering operations and 3D forward modelling were applied on the magnetic data. These geologic features triggered the formation of rollover anticlines and faults that serve as structural traps in the study area. The filtered residual magnetic data revealed geologic structures characterized with NE - SW, N - S, and E - W orientations. The 3-D models detected the faulted crustal blocks, gradient zones, and intra-basement compositional magnetic variations. Furthermore, some prominent horst and graben structures as well as related normal faults characterized with distinct magnetic signatures were observed. Faults of base magnetic (of various compositions) were observed to be the fabricating mechanisms of the magnetic anomalies. Collectively, these structures influenced the patterns of magnetic anomalies with direct effects on the hydrocarbon trapping systems, as well as the pathways and accumulation zones for hydrothermal minerals. On the whole, the interpreted results revealed that the basement surface is rippling. Additionally, the depth result showed sedimentary thicknesses that ranged from 4–10 km. Again, the estimated crustal thickness varied from 14 to 19 km. This study has displayed the capabilities of the magnetic method in mapping the depth and configuration of basement rocks, which are crucial in controlling the formation of structural traps. Identifying these basement structures early helps in understanding the overall geological framework and potential hydrocarbon systems.

Fuzzy c-mean (FCM) integration of geophysical data from an iron-oxide copper gold (IOCG) deposit under thick cover

Geophysical methods depend on a range of physical and chemical mechanisms, and each method has different sensitivities and resolution of Earth parameters, and over different scale lengths. Additionally, such geophysical methods will also have their own statistical characteristics. Thus, it is a significant challenge to combine different methods through a single inversion framework. Rather than attempting to find an optimal and single model for different geophysical responses, an alternative approach is to use FCM clustering to identify clusters of parameters from two or more different geophysical data sets or models that have similar statistical properties. In this paper, we apply the FCM approach to integrate data and model sets for an array of 100 broadband magnetotelluric (MT) and 100 passive seismic receivers spaced 1 km apart on a 10 by 10 grid above the Vulcan IOCG prospect in the Olympic Cu–Au Province, southern Australia. The challenge for exploration of the Vulcan prospect is that it lies beneath 750 m of regolith sedimentary cover, no single geophysical method provides a unique characterization of the deposit geometry, and drilling is very expensive. Fuzzy c-mean cluster analyses are undertaken in 2D for gravity data and shear-wave velocity model data for basement depths beneath cover and in 3D for shear-wave velocity and electrical resistivity model data. Fuzzy c-mean clustering is shown to provide a simple and efficient method of integrating different geophysical measurements to produce a geological framework that can be verified with drilling information.

Geochemistry, petrogenesis and geological implication of granitic rocks in Igarra area, southwestern Nigeria

The Igarra area in southwestern Nigeria hosts a diverse suite of granitic rocks that play a significant role in understanding the regional geological framework. This study employs a comprehensive geochemical and petrogenetic approach to unravel these granitic rock’s origin, evolution and geological implications. A comprehensive geochemical analysis was conducted on samples of the granitoids. The results showed moderate to high SiO2, Na2O and K2O, with average compositions of 68.95%, 3.50% and 4.09%, respectively. The total alkalis are characterised by low MgO, CaO, TiO2 and P2O5, consistent with metaluminous to weak peraluminous compositions. The granite primarily falls within the high-K calc-alkaline region, exhibiting distinctive patterns in rare earth elements, with notable depletion in Nb, P and Ti. Geochemical modelling suggests that the granitoids originated from incomplete melting of metasedimentary source rocks under low to moderate pressure conditions, with limited crustal contamination. Trace element discrimination diagrams indicate a collisional tectonic setting for the Igarra granitoids, interpreted to have formed during continental collision. This mixed-source model suggests a complex magmatic system involving both crustal and mantle contributions, with potential interaction between these diverse melt components during the formation of the granites. This study offers fresh perspectives on the evolutional setting of the Igarra granitoids, understanding the geological effect of the Pan-African belt in Southwestern Nigeria and its broader implications.

Ecological and Geological Environment Risk Assessment of Wangwa Mining Area Based on DInSAR Technology

Mining activities in coal mining areas have exacerbated ecological and geological environmental risks. To explore the impact of mineral resources on the ecological and geological environment risk (EGER) in coal mining areas, we developed a novel ecological and geological risk assessment framework. This framework first quantifies the impact of mining activities on the surface of coal mining areas using remote sensing interpretation and Differential Interferometric Synthetic Aperture Radar (DInSAR) technology. Then, this framework selected six indicators, including subsidence, surface occupation and damage, FVC, RSEI, precipitation, and temperatures. The weights of the evaluation indicators were calculated using a coupled weighting model combining the Analytic Hierarchy Process (AHP) and the Entropy Method (EM). This approach was applied to the Wangwa mining area to assess its ecological and geological risks. The results show that the surface subsidence increase year by year. The EGER in the study area was medium and the change rate of the EGER index in Wangwa mining area from 2017 to 2022 was −0.460 to 0.598. The EGER index increased southwest of the study area but reduced in the pre-investigation area and north of the investigation area. This study can support decision-making to reduce the adverse environmental impact of coal mining activities.

Dynamic interaction of heavy metals and mineralogical shifts in stream sediments exposed to MSW landfill leachate in a semi-arid basaltic terrain

Investigating concentrations and spatial patterns of physicochemical parameters in landfill leachate and their profound impacts on stream sediments is an important issue for environmental sustainability. Therefore, the present study showed that the specifics landfill leachate and its interactions with stream sediments within the unique geological context of semi-arid basaltic terrain of the Deccan Volcanic Province in Pune, India. Employing advanced geo-accumulation indices and crystal phase differentiation methods, the study unveils the intricate metamorphosis of heavy metals and mineralogical composition, tracing the transformative journey from leachate to sediments. Noteworthy revelations emerge, particularly in the striking associations between heavy metals and the mineralogical composition, which encompasses primary and secondary minerals (calcite, quartz, and Fe–Mg oxides). These findings underscore the acceleration of weathering processes within this distinctive geological milieu. The 'geo-accumulation index' exhibits pronounced elevations in proximity to the landfill site, with persistence downstream, reliant upon the evolving weathering and accumulation dynamics. The lower reaches of the study area have higher concentrations of various heavy metals (Fe, Mn, Zn, Cr, Cu, Ni, Co, Hg, As, and Cd). These heavy metals are primarily sequestered within silt-dominated sediments conquered by augite, olivine and plagioclase minerals. Present research reveals the complex interplay between heavy metals in leachate and their physical and chemical interactions with sedimentary materials. These gradational shifts in mineralogy and geochemistry serve as compelling evidence of the transformative impact of leachate discharge within the distinctive basaltic geological framework. This study offers valuable insights into the complex environmental processes occurring at the intersection of landfill leachate and natural geological formations, enhancing the understanding of the dynamic geochemical interactions that shape this semi-arid basaltic terrain.

Gravity Investigations Applied to the Geological Framework Study of the Mambasa Territory in Democratic Republic of Congo

This study concerns the gravity survey carried out in the territory of Mambasa in the province of Ituri in DR Congo, with the aim of studying its subsurface framework. We applied Free-Air and Bouguer corrections to the gravity measurements in order to eliminate gravity variations of non-geological origin. As for the graphical representation of the results, the spatial interpolation tools were useful to us in the elaboration of Bouguer anomaly maps. Then, we classified the study zone into Bouguer anomaly zones based on intensity. Gravity highs could indicate basement uplifts due to compressional movements. These uplifts would have led to the formation of granite domes which could be associated with mineralization. The enormous gravity depression would, for its part, be synonymous with a ditch or the presence of very low-density geological formations. The gravity profiles drawn support the analyzes of the maps: the anomaly curves are very fluctuating and uneven, highlighting several gravity highs and depressions. These fluctuations are probably induced by the presence of faults which separate the different anomaly zones.

2.13 Ga Lawsonite/Barroisite-Bearing E-Morb Signature Metagabbro Associated with Spinel Metaperidotite from Itaguara (São Francisco Craton, Brazil): Oldest Blueschist-Facies Fragment of Oceanic Moho?

In close association with Paleoproterozoic retroeclogite and accretionary prism-related mica-quartz schist, a 2.13 Ga (metamorphic titanite U-Pb age) lawsonite/barroisite-bearing E-MORB signature metagabbro associated with spinel metaperidotite is found in the Itaguara Sequence from southern São Francisco craton, Brazil. Petrography and pressure-temperature equilibrium phase diagrams suggest that the metagabbro experienced blueschist-facies metamorphism, attaining peak metamorphic conditions at ~16 kbar and ~450 °C during subduction. The retrograde metamorphic path crossed epidote amphibolite-facies, in which the mineral assemblage found in metaperidotite (olivine, clinopyroxene, spinel, serpentine, chlorite, talc, and tremolite) was stable during a ca. 2.1 Ga continental collision-related exhumation that occurred between the Archean Campo Belo/Bonfim and Divinópolis complexes. This geological framework suggests that the metagabbro and adjacent spinel metaperidotite represent a subducted and exhumed blueschist-facies fragment of a Paleoproterozoic oceanic Mohorovičić (Moho) discontinuity, thus establishing the Itaguara metagabbro as the oldest-known occurrence of retrogressed blueschist and providing evidence for the activity of the modern-style plate tectonics more than 2 Gyr ago.

Compositional balance analysis for Cu–Zn(±Co) geochemical anomaly mapping in Trøndelag county, Norway

Trøndelag county has been recently the focus of a new mineral exploration wave given its well-known base metal mineralization potential associated with the occurrence of volcanogenic Cu–Zn (±Co ± Ag ± Au) massive sulfide deposits (VMS). This study evaluates a regional low-density soil sampling survey by implementing principal component analysis (PCA), and compositional balance analysis (CoBA) to target prospective areas for base metal mineralization. Principal component analysis indicates a dominant base metal mineralization signature characterized by a correlation between As and Cu–Cr–Co–Ni, which is consistent with the occurrences of mafic metavolcanic and associated low K–Ca metasedimentary rocks. However, several other Cu–Zn occurrences hosted in K- and/or Ca-rich (meta-)sedimentary (e.g., Røros districts) and felsic (meta-)igneous lithologies have been overlooked by this approach. Data- and knowledge-driven balances (i.e., isometric log-ratios) were then constructed to enhance these “weaker” Cu–Zn (±Co) mineralization fingerprints. Most of the data-driven balances (dcobals) are shown to be very noisy, and less useful for base metal geochemical anomaly mapping compared to their more coherent knowledge-driven counterparts (kcobals). However, the kcobals (e.g., for Cu, Zn and Co) highlight relatively large anomalous areas, which makes them less practical if used as individual exploration vectors. To further define zones of economic interest, common anomalous areas (defined as kcobal >75th percentile) have been filtered out from selected kcobal pairs. This has resulted in the identification of several prospective areas that correspond with 15%–20% of the Trøndelag county.This study not only explores the combined use of CoBA and PCA for detecting base metal anomalies, but also elaborates on some factors that can affect the interpretation and performance of multivariate approaches (e.g., mineralization/alteration extension versus survey resolution, geological framework, and deposit type). The visualization and implementation of CoBA presented in this paper aim to improve geoscientists’ understanding of the reach and limitations of using isometric log-ratios for mineral exploration studies.

Gamma spectrometry data suggest opportunities for mineral research in Alagoas, Brazil

This article presents the processing and quantitative interpretation outcomes of aero-gamma-spectrometric data within six regions renowned for copper and iron occurrences in Alagoas State, Brazil, situated within the geological framework of the Sergipan Orogen. The study primarily focuses on radioelement concen-tration data and its derived relationships, encompassing the creation of a ternary map and the utilization of targeting techniques to identify radiometric anomalies, such as potassium and anomalous uranium, along with the Factor F. These relationships enable the identification of behaviors associated with distinct geological models of mineralization, establishing connections between geophysical anomalies and well-known mineral occurrences. By integrating concentration information of radioelements K, Th, and U, in conjunction with geological data and existing mineralizations, the radiometric distributions of the region are thoroughly scrutinized. Radiomet-ric ratios and ternary maps serve to facilitate the identification of enrichment centers for target minerals and the observation of desirable radiometric signatures. Hydrothermal enrichment enhancement techniques unveil a more pronounced correlation between copper targets and potassium (K) anomalies, whereas iron targets ex-hibit a relationship with uranium (U) enrichment. A ternary map, amalgamating anomalous potassium, K/Th ratio, and Factor F, aids in the identification of hydrothermal alterations. Magnetic maps emphasize anomalies near significant indications, accentuating structurally advantageous contours for hydrothermal enrichment and contacts with magnetic minerals associated with iron deposits. Future exploration endeavors should accord pri-ority to these selected areas to unveil their mineral potential. Furthermore, the findings from this study offer valuable insights into the radiometric characteristics and their associations with ore deposits, thereby guiding investigations in other mineral-rich regions, always considering local geology as a vital initial datum.

Tectonic influence on the evolutionary dynamics of deep-water channel systems along the active accretionary prism margin in the Rakhine Basin, Myanmar: A high-resolution 3d seismic analysis

This study reveals the morphological transformations of a deep-water channel system within the Rakhine Basin in the northeastern Bay of Bengal through a comprehensive analysis of high-resolution 3D seismic data integrated with drilling logs. Employing the “source-channel-sink” paradigm, this investigation examined the impact of various factors, including tectonic transformations, sediment influx, slope dynamics, climatic changes, and relative sea-level fluctuations, on the evolutionary trajectory of these channel systems. Applying precise time-slicing techniques integrating root-mean-square amplitude attributes, coherent amplitude attributes, and horizontal amplitudes on seismic profiles, this investigation recognized three distinct stages in the evolution of channel-levee complexes (CLCs): the Middle Miocene erosional deep-water channel-levee complex (CLC-1), the Pliocene erosional-depositional deep-water channel-levee complex (CLC-2), and the Pleistocene depositional deep-water channel-levee complex (CLC-3). Comparative analysis revealed that the CLC-3 exhibits unique characteristics, including shallower channel depth (D), wider channel width (WC), extensive U-shaped cross-sectional area (S), broader natural levee width (WL) and height (H), and the highest tortuosity coefficient (LC/LS) when contrasted with the other two CLCs. Furthermore, this study substantiated how tectonic processes, primarily the collision between the Indo-Eurasian plates, resulting in the Himalayan and Indo-Burma Range orogenies, have shaped the region's geological and climatic framework, thereby influencing monsoon circulation and precipitation patterns, which in turn augmented detrital material influx into the basin. Moreover, this tectonic collision has led to gradual changes in the slope gradient of the Rakhine Basin and its deep-water areas, impacting internal flow velocities and channel curvature, thus governing deep-water channel systems' development and spatial distribution. Also, episodic sea level fluctuations were identified as significant contributors to sediment transport from shelves to deep-water regions and sediment deposit reworking. Overall, this study underscores the role of tectonic changes after the Eocene in driving the evolutionary dynamics of the deep-water channel system within the Rakhine Basin, Myanmar.

Origin and evolution of a porphyry-skarn-stratabound system: constraints from geology, magmatic-hydrothermal zircon U–Pb and molybdenite Re–Os geochronology, and in situ S isotopes of the Dongguashan Cu(–Au) deposit, eastern China

Intrusion-related stratabound deposits within Late Carboniferous carbonate units are an abundant and highly economically significant ore type in eastern China. In such deposits, stratabound mineralization commonly coexists with porphyry and/or skarn mineralization, and the vast majority of reserves (>90 %) are derived from extensive stratabound orebodies, which are easy to exploit and of great interest to geologists. However, it is unclear whether these deposits were formed via the Late Carboniferous seafloor sedimentary exhalation formation or the Early Cretaceous magmatic-hydrothermal processes. Moreover, the fluid and sulfur isotope variations within porphyry-skarn-stratabound systems have not been adequately constrained. We investigated the Dongguashan deposit, one of the largest and most representative stratabound Cu(–Au) deposits in eastern China. Three mineralization types were recognized based on field and petrologic studies: porphyry, skarn, and stratabound. In the stratabound mineralization zone, magmatic and hydrothermal zircons from laminated ores yielded concordant U–Pb ages of 137.3 ± 1.1 and 135.7 ± 1.4 Ma, respectively, while molybdenite samples from vein-like ores yielded Re–Os model ages of 137.8–133.1 Ma (isochron age, 135.9 ± 1.4 Ma). These ages were consistent with the zircon U–Pb age of quartz monzodiorite (137.8 ± 1.7 Ma). A total of 146 in situ S isotope analyses yielded δ34S values (1.9–7.4 ‰) indicating that the sulfur was derived from a magmatic source. Therefore, the Dongguashan deposit resulted from Early Cretaceous magmatism rather than submarine exhalative sedimentary processes. The fluctuations in S isotopes of sulfides across the three mineralization types are attributable to different factors (pH, temperature, and oxygen fugacity) during the evolution of hydrothermal ore-forming fluids. This study demonstrates the importance of geochronology of mineralization and in situ sulfur isotope analysis under robust geological and petrographic frameworks, which can yield information about the ore-forming processes and ore genesis.

Geologic limitations on a comprehensive Anthropocene

Following its advent as a concept, the Anthropocene has flourished as a new worldview in academic and public communities alike. Yet, the Subcommission on Quaternary Stratigraphy recently voted against formally ratifying the Anthropocene as an Epoch, pointing to the restrictive geologic framework, and highlighting the need for a globally represented and synchronous marker. In this Viewpoint, we utilize global bibliographic data, Google search data, IPCC authors, and the Global Climate Risk Index (GCRI) to examine the global diversity of the Anthropocene discourse by measuring academic interest and public engagement in the topic, while also considering the proportional influence, justice, and inclusivity of this discourse. We argue that the conceptual and geological frameworks of the Anthropocene share a complex and non-translatable relationship. Further, we urge reconsideration of geologically rigid definitions in the spirit of recognizing holistic identification of human impacts to the Earth System, while also addressing the gaps in global influence with this pressing concept. Last, we explore successful examples integrating disparate disciplinary perspectives to achieve greater understanding of the Anthropocene and discuss avenues for future directions in the areas of human-environment interactions, as well as environmental justice and equity.

Coastal Groundwater Bodies Modelling Using Geophysical Surveys: The Reconstruction of the Geometry of Alluvial Plains in the North-Eastern Sicily (Italy)

The integration of various geophysical methodologies is considered a fundamental tool for accurately reconstructing the extent and shape of a groundwater body and for estimating the physical parameters that characterize it. This is often essential for the management of water resources in areas affected by geological and environmental hazards. This work aims to reconstruct the pattern and extent of two groundwater bodies, located in the coastal sectors of the North-Eastern Sicily, through the integrated analysis and interpretation of several geoelectrical, seismic and geological data. These are the Sant’Agata-Capo D’Orlando (SCGWB) and the Barcelona-Milazzo (BMGWB) Groundwater Bodies, located at the two ends of the northern sector of the Peloritani geological complex. These two studied coastal plains represent densely populated and industrialized areas, in which the quantity and quality of the groundwater bodies are under constant threat. At first, the resistivity models of the two groundwater bodies were realized through the inversion of a dataset of Vertical Electrical Soundings (VES), constrained by stratigraphic well logs data and other geophysical data. The 3D resistivity models obtained by spatially interpolating 1D inverse VES models have allowed for an initial recognition of the distribution of groundwater, as well as a rough geological framework of the subsoil. Subsequently, these models were implemented by integrating results from active and passive seismic data to determine the seismic P and S wave velocities of the main lithotypes. Simultaneous acquisition and interpretation of seismic and electrical tomographies along identical profiles allowed to determine the specific values of seismic velocity, electrical resistivity and chargeability of the alluvial sediments, and to use these values to constrain the HVSR inversion. All this allowed us to recognize the areal extension and thickness of the various lithotypes in the two investigated areas and, finally, to define the depth and the morphology of the base of the groundwater bodies and the thickness of the filling deposits.

Assessing the potential for CO2 storage in saline aquifers in Brazil: Challenges and Opportunities

AbstractThis study underscores the critical role of carbon capture and storage (CCS) in mitigating greenhouse gas emissions and addresses the potential for CCS projects in saline aquifers in Brazil, one of the world's largest carbon emitters. The country's ability to adopt CCS is significantly influenced by the availability of data related to regional CO2 storage potential and identifying suitable geological framework for CO2 injection. While oil and gas reservoirs have traditionally been prioritized, saline aquifers represent an underexplored and potentially higher capacity storage option. Despite Brazil's 31 sedimentary basins, the data quantity and availability for these contexts remain insufficient for advanced studies on the geological storage of CO2 considering saline aquifers. An initial study was conducted indicating five potential targets in the Paraná and Potiguar Basins for geological storage in saline aquifers based on available public data, mainly drilling data. This review reveals substantial challenges related to the evaluation of Brazil's CO2 storage capacity, such as the lack of modern seismic studies, the absence of a regulatory framework for CO2 storage, and insufficient investment in new well exploration. These challenges necessitate multistakeholder collaboration, the development of a supportive regulatory environment, and investment in extensive site characterization campaigns. Addressing these barriers is fundamental to realizing the country's CCS potential and contributing to global decarbonization efforts. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

From Geoheritage to Geosites at the Oeste Aspiring Geopark (Portugal)

Geoheritage and geosites have been assessed as part of the work supporting the application of the Oeste Aspiring Geopark, in West Central Portugal, for an UNESCO Global Geopark. The geological framework is presented, describing the regional evolution of the Lusitanian Basin, related to the Mesozoic opening of the North Atlantic, since the Late Triassic until the Late Cretaceous, followed by the Cenozoic inversion of the basin, related to the Alpine orogeny. The overall geodiversity of the territory is described, and the main geological highlights are presented.Within the scope and objectives of a Geopark, the criteria for the definition of geosites are presented and discussed. Geoconservation, geoeducation and geotourism have been considered to define 80 geosites, with different characteristics, purposes, relevance and potential. Six different encompassing themes have been defined, each one with a specific storytelling. Geoconservation issues are also addressed, showing the importance of protection strategies for the geosites at a local scale.

Three-stage niobium mineralization at Bayan Obo, China.

The Chinese Bayan Obo deposit is a world-class rare earth element (REE) deposit with considerable niobium (Nb) and iron (Fe) resources. A complete genetic understanding on all metals is fundamental for establishing genetic models at Bayan Obo. With extensive research being focused on REE enrichment, the timing and controls of Nb enrichment remain unresolved at Bayan Obo, which is mainly due to the challenges in dating, i.e. multistage thermal events, fine-grained minerals with complex textures and the rare occurrence of uranium-enriched minerals with mature dating methods. Based on robust geological and petrographic frameworks, here we conducted ion probe uranium-lead (U-Pb) dating of ferrocolumbite to unravel the timing, hence the genesis of Nb mineralization. Three types of hydrothermal ferrocolumbites-key Nb-bearing minerals-are identified based on their textures and mineral assemblages. They yield U-Pb ages of 1312±47 Ma (n=99), 438±7 Ma (n=93), and 268±5 Ma (n=19), respectively. In line with deposit geology, we tentatively link the first, second and third stage Nb mineralization to Mesoproterozoic carbonatite magmatism, ubiquitous early Paleozoic hydrothermal activity, and Permian granitic magmatism, respectively. While quantifying the contribution of metal endowment from each stage requires further investigation, our new dates highlight that multi-stage mineralization is critical for Nb enrichment at Bayan Obo, which may also have implications for the enrichment mechanism of Nb in REE deposits in general.

An Object‐Based Approach to Differentiate Pores and Microfractures in Petrographic Analysis Using Explainable, Supervised Machine Learning

AbstractPetrographic observations are vital for carbonate pore‐typing, linking geological frameworks to petrophysical behavior. However, current petrographic pore typing is manual, with the qualitative to semi‐quantitative results not easily fitted into quantitative subsurface characterization. Some recent studies have automated this process using supervised machine learning (ML) and deep learning (DL), focusing on simple pore morphological features, and have reported high classification accuracies for several complex pore types. However, there are concerns about the validity of these studies due to conceptual and technical flaws in their collective approach. This study was aimed at a more fundamental problem, classifying between open microfractures and open pores in petrographic thin sections using an object‐based approach and explainable supervised ML. We analyzed 18 carbonate thin sections from the USA, numerically representing them using five shape features: compactness, aspect ratio, extent, solidity, and formfactor. Using a labeled data set of 400 microfractures and 400 pores, we evaluated nine of the most widely used supervised models. All models showed high testing accuracies (89.58%–90.42%). Interestingly, complex non‐linear models did not significantly outperform simpler linear ones. Compactness and aspect ratio were the most informative features. However, the labeled data sets did not reflect the overall data set's complexity, which suggested that high accuracies in similar studies might be due to curated data sets rather than accounting for the true complexity of carbonate pore systems. The study concludes that simple shape features are ineffective for classifying carbonate pore types. It is hoped that this study will provide a foundation for more robust artificial intelligence‐assisted pore typing.