Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)

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TephAta – an online collection of tephra datafrom the Atacama Desert
(Copernicus Publications, 2026-06-02) Sáez, Alberto; Gimeno Torrente, Domingo; Cabrera, Lluís; Rodríguez-Araneda, Inés; Wagner, Bernd; Bareth, Georg; Wennrich, Volker; Leicher, Niklas; Feldmar, Vincent; Quezada, Andrés; Vásquez, Paulina; Sepúlveda, Fernando; Frank Wombacher, Frank; Lagos, Markus; Kramm, Tanja; González, Gabriel; Kuiper, Klaudia; Breitkreuz, Christoph
Tephrostratigraphy and tephrochronology are powerful tools using volcanic ash (tephra) layers for establishing stratigraphic correlations and/or to obtain chronological information for different kinds of sedimentary archives. To develop robust tephrostratigraphic frameworks it is essential to precisely characterize the physical, geochemical and chronological properties of tephra layers and their sampling sites. These frameworks allow newly discovered tephra layers to be correlated with established sequences, providing stratigraphic and chronological context and enhancing reconstructions of the spatial and temporal patterns of regional volcanic activity. Tephrostratigraphic frameworks have been developed or are currently emerging in many regions of the world. However, for some regions their potential remains underutilized. One such region is the Atacama Desert of northern Chile, despite its long history of frequent volcanism and associated tephra deposition. Within the framework of the Collaborative Research Centre “Earth – Evolution at the Dry Limit” (CRC1211), the glass phase geochemical compositions of Pleistocene tephra layers were recently systematically investigated to refine their stratigraphic and chronological placement. Alongside this effort, a dedicated tephra database, TephAta was created to provide a long-term repository for tephrochronological research in the Atacama Desert. TephAta enables the comprehensive digital documentation of diverse tephra-related datasets within a single platform and offers search functionalities that support and streamline ongoing expansion of the regional framework, following FAIR (findability, accessibility, interoperability, and reusability) data principles. A first data release contains 106 tephra samples from 91 deposits, with continued spatial and temporal growth planned. All data are accessible via the TephAta portal (https://www.crc1211db.uni-koeln.de/tephata, last access: 29 May 2026) and datasets described in this paper are available at https://doi.org/10.60520/IEDA/114209 (Leicher, 2026). Beyond serving as a stratigraphic and chronological tool for paleoenvironmental or mapping studies, TephAta also facilitates investigations into the regions explosive volcanic history and supports volcanic hazard and risk assessment.
Investigating isotopic markers for hazelnut geographical authentication: Promising variables and potential applications
(Elsevier B.V., 2024-08-15) Torres Cobos, Berta; Rosell, Mònica; Soler, Anna; Rovira, Mercè; Romero, Agustí; Guardiola Ibarz, Francesc; Vichi, S. (Stefania); Tres Oliver, Alba
Hazelnuts' features and price are influenced by their geographical origin, making them susceptible to fraud, especially counterfeit claims regarding their provenance. Stable isotope analysis is a recognised approach to establish the geographical origin of foods, yet its potential in hazelnut authentication remains unexplored. In this prospective study, we assessed multiple isotopic markers in hazelnuts from different origins and evaluated the most promising variables for geographical authentication by chemometric tools. Our findings indicate that bulk δ18O, along with δ2H and δ13C in the main fatty acid methyl esters, exhibit significant potential in discriminating geographical origins, and 87Sr/86Sr analysis could serve as a proficient confirmatory tool. Though no single marker alone can differentiate between all the studied origins, employing a multi-isotopic approach based on PLS-DA models achieved up to 92.5 % accuracy in leave-10 %-out cross-validation. These findings will probably lay the groundwork for developing robust models for hazelnut geographical authentication based on larger datasets.
Lava deltas, a key landform in oceanic volcanic islands: El Hierro, Canary Islands
(Elsevier B.V., 2022-11) Rodriguez-Gonzalez, Alejandro; Fernandez-Turiel, Jose-Luis; Aulinas Juncà, Meritxell; Cabrera, M.C.; Prieto-Torrell, Claudia; Rodriguez, G.A.; Guillou, H.; Perez-Torrado, Francisco Jose
Marine and subaerial erosion of volcanic ocean islands form coastal cliffs and shore platforms, particularly during stable sea levels. Posterosional lava flows can spill over these coastal cliffs and fill the platforms, leading to the progradation of lava deltas. This work aims to analyze this volcanic rocky coast setting at the island scale and to assess the volcanic constructional and erosive degradational effects on the coast at the scale of one volcanic edifice. El Hierro Island, Canary Islands, exemplifies a rocky coast with an active sea-cliff profile, reflecting its early evolutionary stage as a young ocean volcanic island with no fringing reef. The occurrence of a contemporary insular shelf formed during the Holocene sea-level highstand (<7 ka) allows constraining the ages of those eruptions forming lava deltas affecting this geomorphological landform. A detailed bathymetry around the island allowed us to distinguish 17 eruptions fulfilling this criterion. The Montaña del Tesoro, which occurred about 1050 years BP, is one of these eruptions and was selected as a case study for morphometric modeling integrating subaerial and submarine data at the scale of a volcanic edifice. This eruption was a Strombolian basaltic volcanic event that produced a scoria cone, pyroclastic fall deposits, and lava flows that reached the ocean in the eastern rift zone of El Hierro island. We combine field-based observations with topographic and bathymetric data analysis to reconstruct the pre- and post-eruption Digital Elevation Models (DEMs) and, comparing with present-day DEM, to analyze morphometrically the influence of volcanism on the coastal landscape's development. The resulting landform complexity required the discretization of the lava field according to the coastline evolution and lava front sectors, and the subaerial or submarine lava placement. The pyroclastic materials' total erupted bulk volume (12,829,578 m3) corresponds to a volcanic eruption index (VEI) of 3. This event was primarily effusive. From a dense rock equivalent (DRE) volume of 25,615,424 m3, 87 % flowed as lava, 10 % formed the cinder cone, and 3 % the tephra fall deposits. We quantitatively demonstrate that dominant degradation occurs in the lava field, mainly disturbed by marine erosion. Marine erosion removed 9 % of the erupted volume of lava flows against 1 % by fluvial erosion. This work provides methods and results of great interest with different implications in oceanic volcanic islands, among which we can mention coastal planning (e.g., rock coast evolution) and volcanic risk assessment (e.g., the importance of Holocene sea-level rise on the development of shore platforms facilitating the progradation of lava deltas).
Stratigraphic evolution of a salt-walled basin: the influence of diapirism and compressional tectonics on the sedimentary record of the Estopanyà syncline (South-Central Pyrenees)
(Elsevier B.V., 2024-01-18) Ramirez-Perez, Pedro; Cofrade Rivas, Gabriel; Martín, Juan Diego (Martín Martín); Travé i Herrero, Anna
This contribution describes the influence of diapirism and compressional tectonics in the sedimentary record ofthe Estopany`a and Boix synclines (salt-walled basins) in the South-Central Pyrenees (NE Spain). Based onmapping and logging of five stratigraphic sections, two lithostratigraphic units (LU-1 and 2) along the easterndiapir margin of these synclines and five more (LU-3 to 7) in their inner parts are defined. LU-1 and 2 consist ofmonomictic breccias deposited probably during the Upper Triassic-Oligocene and the Upper Cretaceous,respectively. LU-3 to 7 constitute a marine to fluvial succession of the Tremp Group deposited during the UpperCretaceous to Paleocene. The stratigraphic and sedimentological record indicates that the topography, position,and accommodation space of the Estopany`a and Boix synclines was actively controlled by the evolution of saltstructures from the Late Cretaceous to the Oligocene in response to the advance of the Alpine compression in theSouth-Central Pyrenees. The growth of salt-inflated ridges with a near parallel orientation to the axis of thestudied synclines since the Upper Cretaceous, progressively compartmentalized the Boix syncline until inhibitingsedimentation during the lower Paleocene. In the upper Paleocene, the Alpine compression approached the studyarea increasing salt evacuation and the subsidence of the Estopany`a and Boix synclines. During the early tomiddle Ypresian, onset of compression led to salt expulsion by piercing the sedimentary roof of the inherited saltinflatedridges and forming two salt walls at the eastern margin of the Estopany`a and Boix synclines that weresqueezed and welded (possibly through secondary welds) due to tectonic compression during the Oligocene. Thiscontribution provides a new interpretation of the structural and stratigraphic evolution of the Estopany`a andBoix synclines, proposing an evolutionary model that includes the rejuvenation, growth, and extrusion of saltwalls as deciphered from the stratigraphy, sedimentology, and petrology of the diapir margin breccias and thesedimentary succession of the adjoining salt-embedded basins. Hence, it provides a new analogue study forunderstanding the interplay between compressional tectonics, diapirism, and sedimentation to other inverted saltbasins with precursor salt walls worldwide.
Isotopic and geochemical modeling approach to evaluate abiotic nitrite reduction by ferrous iron
(Elsevier B.V., 2024-01-17) Abu, Alex; Carrey Labarta, Raúl; Navarro Ciurana, Dídac; Margalef Marti, Rosanna; Soler i Gil, Albert; Otero Pérez, Neus; Domènech Ortí, Cristina
Nitrite reduction has often been treated as a biotic process in water treatment systems, but it also occurs abiotically, and it is difficult to distinguish both reactions as they can co-occur at field-scale. The potential reduction of NO2− was tested in 3 anaerobic experimental scenarios using a NO2− bearing solution amended with: i) siderite (FeCO3) (Sid experiment); ii) Fe(II) solution from FeCl2.4H2O(s) (DFe experiment); and iii) siderite mixed with Fe(II) solution (Sid+DFe experiment). Non-sterilized batch experiments were carried out in anaerobic conditions with an initial ratio of nitrogen to dissolved iron of 5 in DFe and Sid+DFe (Sid had no initially dissolved Fe(II)) and 1000 mg L−1 of siderite in Sid and Sid+DFe experiments. At the end of the experiments, the NO2− removed was 3% for Sid, 54% for DFe and 84% for Sid+DFe. The NO2− concentration decrease over time was characterized by an enrichment in the δ15NNO2 of the unreacted NO2−, increasing from −26.9 ‰ to −26.4 ‰ (Sid), −18.0 ‰ (DFe) and −15.9 ‰ (Sid+DFe). The calculated ε15NNO2 for Sid was −11.8 ‰, whereas for DFe was −12.0 ‰ and Sid+DFe was −13.0 ‰, suggesting a common NO2− degradation mechanism in all experiments. The Rayleigh distillation equation showed that the generated N2O was the final product of the abiotic nitrite reduction reaction, and the calculated N2O site preference (SP) was 22.5 ± 0.7 ‰ for DFe and 23.5 ± 0.5 ‰ for Sid+DFe. The continuous N2O measurement showed that only 25.3 ± 5.1% in DFe and 31.0 ± 6.3% in Sid+DFe of the generated N2O in water was recovered in the headspace vials, suggesting that a large portion of the produced N2O(aq) in solution did not diffuse from water. The coupled NO2− reduction and Fe(II) oxidation followed a second-order kinetic reaction with a rate equal to (9.39 ± 0.36)·10−4·[NO2−]·[Fe(II)] (mol L−1 s−1) in all experiments. The experimental conditions supported by the Rayleigh distillation equation using the experimentally calculated ε15N values, coupled with NO2− isotopic data and N2O SP values, showed that biological denitrification had a negligible influence on nitrite reduction and that chemodenitrification was the main NO2− attenuation pathway. A geochemical model coupling the kinetic chemodenitrification, isotope fractionation, aqueous speciation in equilibrium and precipitation and dissolution of calcite has been implemented and reproduced the experimental results. The geochemical model developed in our study can be applied to similar experimental studies and to field-scale studies to predict the efficiency of abiotic nitrite reduction treatments using Fe(II).
Synergies of chemodenitrification and denitrification in a saline inland lake
(Elsevier Ltd., 2024-05-07) Margalef Marti, Rosanna; Thibault de Chanvalon, Aubin; Anschutz, Pierre; Amouroux, David; Sebilo, Mathieu
The interconnection between biotic and abiotic pathways involving the nitrogen and iron biogeochemical cycles has recently gained interest. While lacustrine ecosystems are considered prone to the biotic nitrate reduction (denitrification), their potential for promoting the abiotic nitrite reduction (chemodenitrification) remains unclear. In the present study, batch incubations were performed to assess the potential for chemodenitrification and denitrification in the saline inland lake Gallocanta. Sulfidic conditions are found in top sediments of the system while below (5–9 cm), it presents low organic carbon and high sulfate and ferrous iron availability. Anoxic incubations of sediment (5–9 cm) and water from the lake with nitrite revealed potential for chemodenitrification, especially when external ferrous iron was added. The obtained isotopic fractionation values for nitrite (ɛ15NNO2) were −6.8 and −12.3 ‰ and therefore, fell in the range of those previously reported for the nitrite reduction. The more pronounced ɛ15NNO2 (−12.3 ‰) measured in the experiment containing additional ferrous iron was attributed to a higher contribution of the chemodenitrification over biotic denitrification. Incubations containing nitrate also confirmed the potential for denitrification under autotrophic conditions (low organic carbon, high ferrous iron). Higher reaction rate constants were found in the experiment containing 100 μM compared to 400 μM nitrate. The obtained ɛ15NNO3 values (−8.5 and −15.1 ‰) during nitrate consumption fell in the range of those expected for the denitrification. A more pronounced ɛ15NNO3 (−15.1 ‰) was determined in the experiment presenting a lower reaction rate constant (400 μM nitrate). Therefore, in Gallocanta lake, nitrite generated during nitrate reduction can be further reduced by both the abiotic and biotic pathways. These findings establish the significance of chemodenitrification in lacustrine systems and support further exploration in aquatic environments with different levels of C, N, S, and Fe. This might be especially useful in predicting nitrous oxide emissions in natural ecosystems.
Paleoenvironmental constraints influencing charophyte communities in an Early Cretaceous Karstic Lake, La Pedrera de Meià Konservat-Lagerstätte (Southern Pyrenees): combining geochemical and palaeoecological analyses.
(Springer Verlag, 2025-01-08) Pérez Cano, Jordi; Gil Delgado, Alejandro; Oms, Oriol; Mercedes Martín, Ramon
The combined sedimentological and palaeoecological analysis of charophyte-rich carbonate microfacies is proven to be a useful methodology for the palaeoenvironmental reconstruction of continental settings. However, the integration of these charophyte assemblages with geochemical proxies has not been explored, yet. In the present work, the charophyte-rich muddy carbonates of the Barremian La Pedrera de Meià Konservat-Lagerstätte (Southern Pyrenees, Spain) were studied from a taxonomic, taphonomic, and palaeoecological viewpoint, and the results were later integrated with previously published paleoenvironmental proxies (δ13C, δ18O, and elemental geochemistry). In the studied locality, monospecific Echinochara sp.–Charaxis spicatus meadows are only found in the temporary lakes recorded in the lower stages of lake infilling. The high Al, K, Fe and Ti concentrations and δ18O values previously described in these carbonates indicate meteoric infilling followed by evaporation periods. Freshwater and brackish communities are found in the upper stage of lake infilling. Freshwater settings had mixed meadows with Atopochara–Clavatoraxis, Clavatoroidae utricles–Clavatoraxis, and Ascidiella–Favargerella plants, while the brackish environments, that occurred laterally to freshwater, contain meadows dominated by porocharacean– Charaxis sp., and Echinochara sp.–Charaxis spicatus plants. Miliolids and broken dasycladaceans also occur in these facies. Sr/Ba ratios, REE + Y concentrations, and δ18O values previously reported in these lacustrine carbonates indicate prevalence of freshwater environments with occasional marine influence, which agrees with the occurrence of distinct brackish and freshwater charophyte assemblage and marine-affinity organisms, suggesting that during the last stage of lake evolution, the system was part of a coastal wetland. This work demonstrates that the integration of geochemical, palaeontological and palaeoecological datasets improves the understanding of the fossil continental carbonate settings and their evolution.
Modelling antecedent soil hydrological conditions to improve the prediction of landslide susceptibility in typhoon-prone regions
(Springer Verlag, 2024-04-08) Abancó, Clàudia; Asurza, Flavio Alexander; Medina, Vicente; Hürlimann, Marcel; Bennett, Georgina L.
Most regional landslide susceptibility models do not consider the evolving soil hydrological conditions leading up to a multiple occurrence regional landslide event. This results in inaccurate predictions due to the non-linear behaviour of the terrain. To address this, we have developed a simple and efficient model that incorporates the mid-term evolution of soil hydrological conditions. The model combines a water balance model and a geotechnical model based on infinite slope theory. The analysis of 561 high-intensity rainfall events in a typhoon-prone region of the Philippines revealed that the percolation of water during the 5-month wet season is crucial in determining landslide susceptibility. Consequently, high-intensity rainfall events at the start of the wet season are less likely to trigger landslides, while later events are more hazardous. We analysed the change in landslide susceptibility during the 2018 rainy season by comparing the probability of failure (PoF) before and after three high-intensity rainfall events (July, August and September). Only the event in September caused a significant increase in the probability of failure (PoF). The model showed an accuracy of 0.63, with stable cells better represented than unstable cells. The antecedent hydrological conditions on the lower soil layers are responsible for changes in landslide susceptibility. Our findings support the hypothesis that new approaches to developing hydro-meteorological thresholds for landslide early warning systems should be evaluated, especially in regions with strong seasonality.
Experimental insights into the nucleation and propagation of hydraulic fractures in anthracite coalbed methane reservoirs
(Elsevier B.V., 2025-01-28) Huang, Saipeng; Liu, Di; Gómez Rivas, Enrique; Griera, Albert; Gan, Quan; Xing, Yang
Developing low-permeability Coalbed Methane (CBM) reservoirs can significantly benefit from a comprehensive understanding of hydraulic fracture nucleation and propagation mechanisms, particularly in anthracite CBM reservoirs. This study employs true-triaxial hydraulic fracturing experiments to investigate these mechanisms, with variables including injection flow rate, horizontal stress difference (sH-sh), and bedding orientation. Additionally, we conduct corresponding numerical cases to validate the experimental conclusions. The research also considers re-fracturing instances. For the first time, we utilize a combination of Kaiser tests and the stress transfer function in ANSYS Workbench finite element analysis to accurately restore the confining pressure of the coal sample. The findings suggest that a high initial injection flow rate during hydraulic fracturing can promote fluid leakage and aid in maintaining substantial fracture pressure. Enhanced fracturing efficiency can be achieved through higher injection rates, and it can ensure optimal fracturing efficiency, minimizing roof and floor fracturing in coal reservoirs to prevent fracturing fluid leakage. The presence of a high horizontal stress difference facilitates hydraulic fracture propagation along the direction of the maximum horizontal compressive stress, requiring a greater hydraulic pressure to produce more fracture systems in coal reservoirs. Additionally, a minor deviation in the wellbore injection direction from the bedding orientation assists in creating a complex hydraulic fractured network, although this also requires higher hydraulic pressure to initiate new fractures. In the case of multiple hydraulic fracturing, the second initiation pressure tends to be significantly higher than the first, indicating that a sequential increase in hydraulic pressure aids the formation of additional fractures. Moreover, a simplified numerical simulation has been conducted to corroborate the experimental findings. These insights are crucial in optimizing hydraulic fracturing processes to enhance the permeability of anthracite CBM reservoirs.
Promotion of stable polymorphs and molecular compound formation in mixtures of a high melting fraction of extra virgin olive oil and cocoa butter
(Elsevier B.V., 2026-01-10) Bayés-García, Laura; Calvet Pallàs, Maria Teresa; Sato, Kiyotaka
The complex polymorphic crystallization and melting behavior of mixtures of the high melting fraction (HMF) of extra virgin olive oil (EVOO) and cocoa butter (CB) was analyzed in the present work. All the mixtures prepared for every 10 % concentration ratio were subjected to a cooling procedure from the molten state (50 ◦C) to -50 ◦C at a rate of 2 ◦C/min, and a subsequent heating to the starting temperature at the same rate. Time-resolved synchrotron radiation X-ray diffraction (SR-XRD) experiments, based on simultaneous small- (SR-SAXD) and wide- (SR-WAXD) angle measurements was used to describe the polymorphism exhibited by single HMF and CB, and selected blends of 30CB/70HMF, 50CB/50HMF and 70CB/30HMF. Six (α-2 L, β’3–2 L, β’2–2 L, β’1–2 L, β’2–3 L, β’1–3 L) and two (Forms I and II) polymorphic forms were encountered in single HMF of EVOO and CB, respectively, at the experimental conditions examined. By contrast, in the blends, HMF crystallized in just two phases (β’3–2 L, β’2–2 L), whereas CB was detected in Forms I, II, IV and V. Many difficulties arose in phase identification, due to the large similarities between polymorphs of the raw materials. The addition of CB resulted in a relevant increase of the crystallization and melting temperatures in the mixtures, which were caused by the formation of Forms IV and V of CB, but also the occurrence of a molecular compound (MC) structure. The promotion of more stable forms of CB may be due to the presence of liquid oil (HMF), which accelerated polymorphic transformations by thermodynamic solvent effects. The results obtained in this work may be suitable for the reduction of saturated fats, favoring the predominance of the monounsaturated ones, like oleic acid.
Magmatic Storage and Volatile Fluxes of the 2021 La Palma Eruption
(Wiley, 2023-02-08) Dayton, K.; Gazel, E.; Wieser, P.; Troll, Valentin R.; Carracedo, J.C.; Aulinas Juncà, Meritxell; Perez-Torrado, F.J.
The 2021 La Palma eruption (Tajogaite) was unprecedented in magnitude, duration, and degree of monitoring compared to historical volcanism on La Palma. Here, we provide data on melt inclusions in samples from the beginning and end of the eruption to compare the utility of both melt and fluid inclusions as recorders of magma storage. We also investigated compositional heterogeneities within the magmatic plumbing system. We found two populations of olivine crystals: a low Mg# (78–82) population present at the beginning and end of eruption, recording the maximum volatile contents (2.5 wt % H2O, 1,800 ppm F, 700 ppm Cl, 3,800 ppm S) and a higher Mg# (83–86) population sampled toward the end of the eruption, with lower volatile contents. Despite their host composition, melt inclusions share the same maximum range of CO2 concentrations (1.2–1.4 wt %), indicating olivine growth and inclusion capture at similar depths. Overall, both melt and fluid inclusions record similar pressures (450–850 MPa, ∼15–30 km), and when hosted in the same olivine crystal pressures are indistinguishable within error. At these mantle pressures, CO2 is expected to be an exsolved phase explaining the similar range of CO2 between the two samples, but other volatile species (F, Cl, S) behave incompatibly, and thus, the increase between the two olivine populations can be explained by fractional crystallization prior to eruption. Finally, based on our new data, we provide estimates on the total volatile emission of the eruption.
3D modeling of gas hydrates distribution in South Hydrate Ridge (Cascadia accretionary prism, offshore Oregon) through geological time
(Sociedad Geológica de España, 2024) Cabello López, Patricia; Marin, Mar; Cassola, T.; Falivene Aldea, Oriol; Gil-Ortiz, Marc; Yeste, Luis Miguel; Agustí García-Navarro, Àlvar; Uranga Moran, Rodolfo Martín; Berndt, C.
South Hydrate Ridge (SHR) is an anticlinal structure that is part of the Cascadia accretionary prism, located offshore of Oregon. SHR has been the subject of multiple multidisciplinary studies and oceanographic campaigns focused on understanding the functioning of gas hydrate systems. Herein, we present a 3D dynamic model of SHR that simulates the distribution of gas hydrates over geological time. This model is based on the application on petroleum system modeling tools and builds upon previously published data and results from 2D models already published. The model reproduces the complex structure of SHR and distinguishes a total of 7 stratigraphic units (from the Pliocene to the Present), primarily composed of silty clays and clays interbedded with sands. The model predicts a heterogeneous distribution of gas hydrate saturation in SHR at present, with higher values observed on the flanks of the main ridge and on the crests of secondary highs (maximum values of up to 23% of porosity). According to the model, the initiation of hydrate formation occurred mainly between 1.7 Ma and 1.6 Ma, and its accumulation has persisted throughout the evolution of the ridge, alternating with dissociation in certain areas and moments. Such variable distribution and the alternation of formation and dissociation would respond to the differential growth of the structures forming the SHR. These structures control the availability of gas, which migrates upward through deformed strata, and would influence the distribution of the gas hydrate stability zone.
Rare Earth Element and Yttrium (REY) Hyper-Enriched Karst Bauxites of the Mercedes-Aceitillar Mining District, Sierra de Bahoruco,SW Dominican Republic
(Society of Economic Geologists, 2026-02-23) Domínguez-Carretero, Diego; Proenza Fernández, Joaquín Antonio; Aiglsperger, Thomas Hans; Villanova de Benavent, Cristina; Torró i Abat, Lisard; Pujol Solà, Núria; Bover-Arnal, Telm; Tisora, Àngel; Domènech, Carles; Ramírez, Andrés; Rodríguez, Julio, 1971-; Dold, Bernhard
Rare earth elements, including yttrium (REYs), are the most sought-after among the so-called critical or strategic elements for the low-carbon energy industry. In the past decade, karst bauxite deposits have been targeted as potential nonconventional sources of these elements. The karst bauxite deposits from the Mercedes-Aceitillar mining district, classified as Fe-rich bauxites and bauxites sensu stricto, contain anomalously high REY contents oscillating between 514 and 28,787 ppm (median of 1,489 ppm), making them the most REY-enriched karst bauxites globally. Most of the samples studied are enriched in light rare earth elements (La-Nd; up to 7,449 ppm) and Y (up to 14,830 ppm). However, the most REY-enriched bauxites yield particularly high middle rare earth element (Sm-Gd; up to 4,579 ppm) and heavy rare earth element (Tb-Lu; up to 6,163 ppm) contents. In addition, the studied bauxites contain significant amounts of other critical metals, such as Sc and Ga (median of 62 and 39 ppm, respectively). The mineralogy consists predominantly of Al oxyhydroxides (mostly gibbsite), with variable amounts of Fe oxyhydroxides and kaolinite. The REY mineralogy in samples with high REY contents (>3,000 ppm) consists mainly of REY-bearing phosphates (e.g., monazite, xenotime, rhabdophane, churchite) and/or carbonates (bastnäsite group). In samples with moderate REY contents (<3,000 ppm), the main REY-bearing minerals are Al oxyhydroxides, onto which the REYs are most likely adsorbed. These findings indicate that the potential extraction of REYs and other critical metals, such as Sc and Ga, in the studied bauxites from the Mercedes-Aceitillar mining district could add, on average, an ~20% surplus to the revenue obtained from Al2O3 exploitation. The unprecedented REY contents discovered in these karst bauxites from the Dominican Republic present a unique opportunity to unravel critical metal concentration mechanisms in supergene environments and to develop new geochemical models for nonconventional REY deposits.
The gradual shift from forearc basalt-like to boninite-like magmatism during intra-oceanic subduction-initiation recorded by ophiolitic chromite deposits from Cuba
(Springer Verlag, 2025-10-01) Domínguez-Carretero, Diego; Proenza Fernández, Joaquín Antonio; Pujol Solà, Núria; Gervilla, Fernando; Villanova de Benavent, Cristina; Colás, Vanessa; Núñez-Cambra, Kenya; Piñero-Pérez, E.; Garcia-Casco, Antonio
Cuba contains the largest number of ophiolitic chromite deposits throughout the Americas. Most of these deposits are found within the mantle section of the Eastern Cuba and Camagüey ophiolitic massifs, which contain four different chromite mining districts (Camagüey, Mayarí, Sagua de Tánamo, and Moa-Baracoa). In addition to their potential as economic resources, chromite deposits are also excellent petrogenetic indicators to interpret the nature of ancient upper mantle, processes of melt formation in the mantle, and large-scale geodynamic processes. In this sense, major and trace elements of unaltered Cr-spinel cores together with chromitite whole-rock PGE composition reveal that high-Al Camagüey and Moa-Baracoa chromite districts were formed in equilibrium with forearc basalts (FAB)-like magmas during the incipient intra-oceanic subduction of the proto-Caribbean lithosphere underneath the Caribbean lithosphere, in a subduction-initiation process. Conversely, the high-Cr Mayarí chromite district was formed in equilibrium with more hydrated melts of boninitic affinity, typical of a more advanced stage of the subduction-initiation process. Nonetheless, the shift from FABlike to boninite-like magmatism in an intra-oceanic subduction is gradual. This progressive change is well-recorded in the Sagua de Tánamo district that contains both high-Al and high-Cr chromitites. Thus, the studied ophiolitic chromitites allow tracing the complete magmatic evolution of an intra-oceanic subduction-initiation process. Furthermore, our data exhibits that accessory Cr-spinel composition of peridotites surrounding chromitites can be used as a prospecting indicator to anticipate the composition of ophiolitic chromitite bodies. Systematically, Cr-spinel from dunites associated with highAl chromite deposits have lower Cr# values compared to the accessory Cr-spinel from the associated harzburgites. On the contrary, Cr-spinel from dunites of high-Cr chromite deposits show higher Cr# compared to the accessory Cr-spinel from the host harzburgites.
Metales críticos en óxidos de manganeso formados en condiciones supergénicas: Estudio preliminar
(Sociedad Española de Mineralogía, 2025) Villanova de Benavent, Cristina; Domínguez-Carretero, Diego; Fernando Nieto; Llovet Ximenes, Xavier; Pujol Solà, Núria; Domènech Ortí, Cristina; Galí Medina, Salvador, 1949-; Proenza Fernández, Joaquín Antonio
Los óxidos de manganeso (también llamados oxihidróxidos de Mn) son la principal mena de Mn, pero también pueden contener valores interesantes de Ni, Co y otros metales que actualmente se consideran críticos o estratégicos. Estos minerales son frecuentes en perfiles lateríticos de Ni-Co en todo el mundo (p.ej., Manceau et al., 1987, Putzolu et al., 2018; Domènech et al., 2022), y se han descrito tanto en depósitos de tipo óxido (Roqué-Rosell et al., 2010), silicato hidratado (Domènech et al., 2022) y de tipo arcilla (Tauler et al., 2017). También se pueden encontrar en depósitos de bauxitas (Bárdossy, 1982), aunque estos últimos son menos conocidos. Lo que tienen en común los óxidos de Mn que se forman tanto en lateritas como en bauxitas es que mayoritariamente se trata de asbolana ((Ni,Co)xMn(O,OH)4·nH2O; sistema hexagonal) y/o litioforita (Al,Li)MnO2(OH)2; sistema trigonal, aunque el Li no se considera esencial; Bárdossy, 1982; Manceau et al., 1987; Roqué-Rosell et al., 2010; Tauler et al., 2017; Domènech et al., 2022), aunque se han identificado también otros como la romanechita (Putzolu et al., 2018) o la rancieíta (Bárdossy & Brindley, 1978). La asbolana y la litioforita son especies minerales válidas según la International Mineralogical Association (IMA), se encuentran formando agregados masivos, de grano fino y de baja cristalinidad, pero con una estructura atómica en forma de capas (Post, 1999). En el caso de la asbolana, la estructura está constituida una alternancia de capas ocupadas por Mn4+, Ni y Co (Chukhrov, 1982). Con el fin de obtener una caracterización detallada de los distintos óxidos de Mn descritos en los depósitos lateríticos y bauxíticos estudiados, esta contribución combina datos de DRX de polvo, SEM, EMP, LA-ICP-MS y TEM de óxidos de Mn muestreados en distintos depósitos lateríticos de Ni-Co y bauxitas kársticas, y a distintos niveles de los perfiles de meteorización.
Re-minado de balsas de residuos del procesamiento hidrometalúrgico de menas lateríticas Ni-Co, un potencial recurso de metales críticos
(Sociedad Española de Mineralogía, 2025) García-Tudela, Matías; Proenza Fernández, Joaquín Antonio; Pons, José Alberto; Domínguez-Carretero, Diego; Villanova de Benavent, Cristina; Aiglsperger, Thomas Hans
El despliegue de las tecnologías energéticas necesarias para la descarbonización conlleva un aumento significativo de la demanda de minerales (Comisión Europea, 2023). Según la Agencia Internacional de la Energía (2024), en un escenario de cero emisiones, de todos los minerales críticos, la segunda inversión de capital hasta 2040 será en la minería de Ni, con una inversión estimada de 160 mil millones de dólares. En este contexto, los depósitos lateríticos de Ni-Co contienen aproximadamente el 70% de las reservas mundiales de Ni, representan el 20 % de la producción mundial de Co, y actualmente también constituyen una importante fuente de Sc al mercado mundial. El noreste de Cuba alberga enormes recursos de Ni y Co asociados a depósitos lateríticos (distritos de Nicaro y Bahía de Moa). En estos distritos, las mineralizaciones de Ni y/o Co se encuentran predominantemente en la zona de óxidos, compuesta principalmente por goethita, maghemita y oxihidróxidos de Mn (Domínguez-Carretero et al., 2024). Sin embargo, también hay depósitos cuyos horizontes saprolíticos están bien desarrollados y los cuales presentan concentraciones de Ni elevadas, con abundante serpentina rica en Ni e incluso con fracturas rellenadas por garnierita (Domínguez-Carretero et al., 2024). El procesamiento metalúrgico de las menas lateríticas se realiza mediante dos tipos diferentes de plantas hidrometalúrgicas. La primera utiliza un proceso de lixiviación ácida a alta presión (HPAL) para procesar la mena de la zona de óxidos (horizonte limonítico) y obtener un producto compuesto por sulfuros de Ni+Co. El segundo proceso metalúrgico, llamado Caron, permite el procesamiento de menas procedentes tanto de la zona de óxidos como de la zona saprolítica. En el proceso Caron, mediante una combinación de reducción, lixiviación con NH3, calcinación y sinterización se obtiene un sínter de Ni+Co. Esta intensa actividad extractiva de Ni y Co en el noreste de Cuba durante décadas ha generado balsas de residuos metalúrgicos que tienen volúmenes de millones de toneladas. En esta contribución se presentan nuevos datos sobre la composición química (High Resolution ICP-MS: ICP-SFMS) y la mineralogía (XRD, SEM-EDS, FE-SEM, quantitative target mineralogy (QanTmin)) de las balsas de residuos derivadas de ambos procesos metalúrgicos, con el objetivo de evaluar su posible re-minado como un potencial recurso de metales críticos para la transición energética y digital.
A General Conceptual Petrological Model for the Subsolidus Transformation of Chromitite with Application and Implications
(Oxford University Press, 2025-04-01) Garcia-Casco, Antonio; Pujol Solà, Núria; Novo-Fernández, Irene; Arenas, Ricardo; Rojo-Pérez, Esther; Cambeses, Aitor; Molina, José Francisco; Sánchez Martínez, Sonia; Domínguez-Carretero, Diego; Iglesias, Gabriel; Proenza Fernández, Joaquín Antonio
A general petrologic model for the transformation of chromitite in the FeO–MgO–Al2O3–Cr2O3–SiO2–H2O (FMACrSH) system is presented based in mass-balance and thermodynamic constraints. In the model, the transformation of chromitite reaches the common Crspinel+chlorite assemblage of transformed chromitites upon reaction with external fluid. This metasomatic process takes place in two major sequential steps involving a net-transfer reaction of olivine consumption first ensued by Cr-spinel+chlorite dissolution– precipitation. The first step is completed early in the hydration/metasomatic process producing new Cr-spinel (+chlorite±brucite) with restricted composition close to the composition of reacting mantle Cr-spinel as a function of Cr-spinel/olivine ratio and the stoichiometric coefficients of olivine and Cr-spinel in the net-transfer reaction. The second transformation step, triggered upon exhaustion of olivine, is protracted and continuously produces increasing chlorite and decreasing Cr-spinel contents, the latter with continued more deviated composition from reacting mantle Cr-spinel, as a function of continued infiltration of external fluid. The mass-balance model does not prejudice transformation under isothermal-isobaric conditions, heating, or cooling, but thermodynamic calculations confirm that all these thermal scenarios are possible for the generation of the predicted mineral assemblages and compositions. These calculations demonstrate that extreme Cr-spinel compositions are a strong function of decreasing spinel volume upon reaction progress at reaction sites under strongly overstepped conditions. The application of the model to mantle chromitites of the Cadomian Calzadilla metaophiolite (Ossa-Morena Complex, SW Iberia) allows reinterpreting the thermal scenario for chromitite transformation in a context of prograde metamorphism at near-isothermal-isobaric conditions. Proposals of cooling during transformation of regionally metamorphosed chromitites should be revisited in light of the petrologic model offered.
Strontium-isotope stratigraphy of the Aptian–Albian transition inthe western Maestrat Basin (E Iberia)
((UB). (ICTJA). (IDEA). (UAB). (CSIC), 2025-12-01) Bover-Arnal, Telm; Pascual-Cebrian, Enric; Moreno-Bedmar, Josep Anton; Salas, Ramon (Salas Roig)
The Aptian–Albian transition in the Maestrat Basin (E Iberian Chain) encompasses two lithostratigraphic units:the Benassal and Escucha formations. In some sectors of the basin, such as the western Galve and Las Parrassub-basins, this stratigraphic interval recorded a progressive shift from widespread carbonate platform settingsto coastal siliciclastic-influenced and coal-bearing environments. Due to the transitional nature of this interval,establishing a clear stratigraphic boundary between the upper part of the Benassal Formation and the lower partof the Escucha Formation is challenging. Additionally, there is no unanimous agreement on the age range ofthese formations. To shed light on the stratigraphic location of the boundary between the Aptian and the Albian,strontium-isotope analyses were carried out on thirteen low-Mg calcite oyster shells to derive numerical ages.In the Las Parras Sub-basin, the 87Sr/86Sr values obtained from the siliciclastic-influenced transitional depositsbetween the Benassal and Escucha formations, as well as from the lowermost part of the Escucha Formation,range from 0.707282±0.000002 to 0.707410±0.000002. These Sr-isotope ratios translate into numerical ages that constrain this stratigraphic interval to the early Albian. The oyster shells collected in the Galve Sub-basin exhibit a higher degree of diagenetic alteration. Nevertheless, the least altered specimens analysed from the lower part of the transitional facies between the Benassal and Escucha formations in this latter sub-basin yielded Sr-isotope ratios between 0.707197±0.000003 and 0.707256±0.000002. These values correspond to ages spanning from the latest Aptian to the earliest Albian. Accordingly, in most sectors of the western Maestrat Basin, the Aptian–Albian boundary is likely to be stratigraphically located at the lowermost part of the transitional facies between the Benassal and Escucha formations.
Mineral-driven persulfate activation: the role of recycled concrete alkalinityin oxidative water treatment
(Elsevier Ltd., 2025-10-25) Cappelli, Chiara; Fernández-Lagunas, Albert; Usieto, María; Rosell, Mònica; Torrentó Aguerri, Clara; Domènech Ortí, Cristina; Palau, Jordi; Soler i Gil, Albert
The dissolution of concrete—a prevalent anthropogenic material—generates hyperalkaline, Ca-rich leachatesthat may influence redox processes in subsurface environments. The knowledge of these geochemical processesserves as theoretical framework for the application of recycling concrete material to circular economy systems,providing sustainable alternatives to the concerning issue of the construction waste management while positivelyacting on specific environmental settings. This study investigates the potential of recycled concrete as a longtermalkaline activator for sodium persulfate in In Situ Chemical Oxidation groundwater treatments, with afocus on application in groundwater-recharge interception trenches in the vadose zone. A laboratory-scale studywas conducted using flow-through columns filled with crushed recycled concrete, which was exposed tocontaminated groundwater. The research assessed (i) the ability of concrete to generate and maintain alkalineconditions for persulfate activation, (ii) its mineralogical composition to determine reactivity and surfacepassivation, and (iii) chemical changes occurring upon persulfate addition at two different dosages. Resultsshowed that recycled concrete effectively maintained high pH and buffered the system after persulfate injection,enabling efficient activation of the oxidant and substantial degradation of dissolved organic carbon. The systemwas controlled by the dissolution of concrete aggregates and cement phase together with the carbonation and(re)precipitation of new phases. The role of calcium and aluminium/magnesium silicate hydrates was proven tobe crucial for the stability of the concrete microstructure and for maintaining the alkalinity. These findingsdemonstrate the dual role of recycled concrete for providing long-term alkaline activation of persulfate andmitigating clogging risks, supporting is practical use in groundwater remediation strategies promoting circulareconomy principles. Furthermore, these findings mirror processes observed in different hyperalkaline systems (e.g., radioactive waste repositories, CO2 storage) where mineral-driven redox reactions control contaminant fate and/or carbon sequestration.
Lower Miocene carbonate platforms of the Falcón Basin (NW Venezuela) compared to the offshore Perla Field reservoir
((UB). (ICTJA). (IDEA). (UAB). (CSIC), 2025-10-28) Albert-Villanueva, Eduard; Bover-Arnal, Telm; Ferràndez i Cañadell, Carles; González, Lenin; Esteban, Mateu; Salas, Ramon (Salas Roig)
Based on field data collected in the northern and southern Falcón Basin (Venezuela), this paper presents a comprehensive monograph that reports on the age and sedimentary evolution of the San Luis and Churuguara formations. It integrates platform-to-basin depositional models through facies distribution and stratal architecture, a palaeogeographic reconstruction, larger foraminifera biostratigraphy, sequence stratigraphy, and the evaluation of the accommodation history. An additional aim is to compare these onshore mixed carbonate-siliciclastic systems with the Oligo-Miocene subsurface carbonate reservoir of Perla in offshore Gulf of Venezuela, considered the largest gas discovery ever in Latin America. The carbonate platforms studied formed as a result of a second-order transgressive event, and corresponded to distally steepened or undifferentiated ramps dominated by coralline algae and larger foraminifera. The presence of Miosorites americanus and Annulosorites spiralis dates the San Luis and Churuguara formations to the Early Miocene. The miogypsinid associations identified further distinguish between the Aquitanian and Burdigalian stages. The San Luis and Churuguara platforms exhibit a general aggradational trend, while the Perla carbonates have been interpreted as a retrogradational unit. Third-order T-R sequences interpreted from these successions were mainly influenced by differential tectonic subsidence. Additionally, major regional regressive events in the Falcón Basin and Perla Field coincide with global glaciations, highlighting the influence of eustatic changes. However, the Perla reservoir exhibits significant differences in thickness, spatial extent and sedimentary architecture compared to the onshore equivalents. The differences arise from variations in tectonic and palaeotopographic settings, accommodation and sedimentation rates and influence of adjacent siliciclastic systems. As a result, predicting the sedimentary architecture of carbonate reservoirs in this region using a generalized depositional model has proven to be challenging.

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