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

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Linseed oil-based oleogels with wax versus behenate-based glycerides: crystal polymorphism, microstructure, and gel stability
(Springer Verlag, 2026-01-22) Luo, Ping; Bayés-García, Laura; Calvet Pallàs, Maria Teresa; Li, Xuan; Zhang, Lu
Although oleogels are promising substitutes for saturated fats, their widespread adoption is hindered by multiple factors, among which an insufficient understanding of their crystallization behavior remains a key barrier. This work presents the first systematic analysis of the crystallization behavior in thermo-reversible linseed oil (LO)-based oleogels. The investigation combines in situ X-ray diffraction with thermal and microscopic analyses across a wide temperature range (-80 °C to 80 °C). We compared three natural waxes, sunflower wax (SFW), candelilla wax (CDW), and rice bran wax (RBW), along with two behenate-based glycerides, glyceryl behenate (GB) and fully hydrogenated high erucic acid rapeseed oil (FHR), as gelators for structuring LO. While LO itself exhibited both sub-α and β′ polymorphs, wax-based oleogels predominantly stabilized the β′ form. In contrast, oleogels with FHR or GB showed coexisting α/β′ and α/sub-α forms, respectively. Additionally, a β′ to β transformation was observed upon further heating in FHR-containing oleogels. Although most oleogels exhibited higher oil-binding capacity (OBC) at 5 °C than at 25–35 °C, the GB-containing oleogel achieved the highest OBC at 35 °C. These findings highlight the essential role of gelator polymorphism and crystal morphology in tailoring oleogel properties, guiding the rational design of functional oleogels for specific applications.
Temperature-Driven Changes in the Polymorphism, Microstructure and Thermal Properties of Cocoa Butter/Shea Butter Stearin Blends
(Springer Science + Business Media, 2025) Macridachis González, Jorge; Bayés-García, Laura; Calvet Pallàs, Maria Teresa
The increasing application of cocoa butter alternatives in confectionery products requires a deep understanding of their crystallization behavior in order to maintain and promote desirable quality attributes. Through the combination of X-ray diffraction, microscopic, and thermal analysis techniques, this study explored the polymorphic, microstructural, and melting properties of cocoa butter and shea butter stearin blends with varying compositions. Results showed a more complex polymorphic behavior in blends than in the pure fats, with the coexistence of β′-2L and β′-3L forms, whose occurrence was strongly influenced by both the cocoa butter/shea stearin ratio and the thermal treatments applied. The solid fat content analysis evidenced, at all the analyzed samples, an abrupt falling typical for CB-like melting profile, which occurred between 30 and 35 °C in CB, and shifted to above 35 °C in ShS. Blends with increasing amounts of shea stearin showed a higher thermal resistance, a smoother thermal profile and a delayed β-phase development under isothermal conditions. Moreover, moderate variations of the composition modified the microstructure of the blends, which suggests potential impacts on the texture and sensory perception of products including this fat system.
Characterization of Microbialites Using ERT and GPR: Insights from Neoproterozoic and Mesozoic Carbonate Systems
(MDPI, 2025-12-17) Urruela, Aritz; Casas i Ponsatí, Albert; Lima-Filho, F. P.; Himi, Mahjoub; Rivero Marginedas, Lluís
The detection of subsurface stromatolites remains challenging due to their complex morphology and heterogeneous composition. This study assesses the combined application of Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) for identifying microbialites in two contrasting geological and climatic settings: the Neoproterozoic Salitre Formation in Brazil and the Mesozoic microbialite-bearing limestones in northern Spain. High-resolution ERT profiles processed with raster-based blob detection algorithms revealed subcircular high-resistivity anomalies consistent with the studied microbialite morphologies, with strong resistivity contrasts observed between microbialites and host matrices despite variations in absolute values linked to lithology and soil moisture. In parallel, GPR surveys analyzed with a peak detection algorithm delineated domal reflectors and clusters of high-amplitude reflections that directly captured the internal architecture of stromatolitic buildups. With decimetric vertical resolution, GPR offered unrivaled insights into internal morphology, complementing the broader-scale imaging capacity of ERT. The complementary strengths of both methods are clear: ERT excels at mapping distribution and stratigraphic context, while GPR provides unparalleled resolution of internal structures. Crucially, this work advances previous efforts by explicitly demonstrating that integrated ERT-GPR approaches, when combined with algorithm-based interpretation, can resolve microbialite morphology, distribution and internal architecture with a level of objectivity not previously achieved. Beyond methodological refinement, these findings open new avenues for reconstructing microbialite development and preservation in ancient carbonate systems and hold strong potential for application in other geological contexts where complex carbonate structures challenge traditional geophysical imaging.
Driving magma to the Surface: the 2011-2012 El Hierro volcanic eruption
(Wiley, 2017) Lopez, Carmén; Benito-Saz, Maria A.; Marti Ribas, Josep; del-Fresno, Carmen; García‐Cañada, Laura; Albert Mínguez, Helena; Lamolda, Héctor
We reanalyzed the seismic and deformation data corresponding to the preeruptive unrest on El Hierro (Canary Islands) in 2011. We considered new information about the internal structure of the island. We updated the seismic catalog to estimate the full evolution of the released seismic energy and demonstrate the importance of nonlocated earthquakes. Using seismic data and GPS displacements, we characterized the shear-tensile type of the predominant fracturing and modeled the strain and stress fields for different time periods. This enabled us to identify a prolonged first phase characterized by hydraulic tensile fracturing, which we interpret as being related to the emplacement of new magma below the volcanic edifice on El Hierro. This was followed by postinjection unidirectional migration, probably controlled by the stress field and the distribution of the structural discontinuities. We identified the effects of energetic magmatic pulses occurring a few days before the eruption that induced shear seismicity on preexisting faults within the volcano and raised the Coulomb stress over the whole crust. We suggest that these magmatic pulses reflect the crossing of the Moho discontinuity, as well as changes in the path geometry of the dyke migration toward the surface. The final phase involved magma ascent through a prefractured crust.
From explosive vent opening to effusive outpouring: mineral constraints on magma dynamics and timescales at paricutin monogenetic volcano
(Oxford University Press, 2021) Larrea, Patricia; Albert Mínguez, Helena; Ubide, Teresa; Costa, Fidel; Colás, Vanessa; Widom, Elisabeth; Siebe, Claus
Paricutin volcano is the youngest monogenetic cone of the Michoacán–Guanajuato volcanic field (Mexico), with an excellent historical eruption record from February 1943 to March 1952. The magma emitted during the 9 years of activity was compositionally zoned from basaltic andesite to andesite. This eruption has been considered a classic example of magma differentiation controlled by crustal assimilation combined with fractional crystallization. However, a recent geochemical study of the eruption products points to mantle source heterogeneity and fractional crystallization as the key processes involved in the compositional variability of the magmas. Here we present a detailed petrological characterization of the minerals [olivine, plagioclase, pyroxene, Cr-spinel, and (Ti-)magnetite] to shed light on the processes that led to the chemical evolution of the eruptive products. Our sample set includes the early tephra from the first weeks or months of eruption and the whole sequence of lava flows that followed. The mineral assemblage, their texture, and chemical composition show a systematic evolution between the products from the opening of the explosive vent to the effusive stage. The early tephra are basaltic andesites with oscillatory-zoned olivine and plagioclase, zoned Cr-spinel, and rare pyroxene xenocrysts. In contrast, later erupted tephra and post-January 1944 lavas are basaltic andesites and andesites with normally zoned olivine, Cr-spinel inclusions in equilibrium with the host olivine, and frequent orthopyroxene (after December 1947) with minor chemical zoning. Mineral chemistry data and olivine diffusion timescales, together with whole-rock geochemistry, suggest a convective magma regime with large temperature and oxygen fugacity gradients characterized by short timescales (few days) during the opening stage, followed by a steadier magma regime with longer timescales (few months) and including periodic magma recharge, mixing, and fractional crystallization. In addition, the mineralogical evidence we have gathered does not support considerable crustal assimilation at Paricutin. This study shows that monogenetic eruptions are far from being geochemically simple, and instead involve multiple magma batches with complex storage and mixing stages before eruption.
Unrest signals after 46 years of quiescence at Cumbre Vieja, La Palma, Canary Islands.
(Elsevier B.V., 2020-02-15) Torres-González, P.A.; Luengo-Oroz, N.; Lamolda, Héctor; D'Alessandro, W.; Albert Mínguez, Helena; Iribarren, I.; Moure-García, D.; Soler, V.
Monogenetic eruptions are the most common volcanic activity in the world. However, unrest monitoring data are scarce due to the long intervening quiescence periods. This study analyzes unrest signals recorded in one of the largest monogenetic fields in the Canary Islands, Cumbre Vieja (La Palma). Two seismic swarms were registered in October 2017 and February 2018 with b-values of 1.6 ± 0.1 and 2.3 ± 0.2 respectively suggesting an intense magmatic fluids contribution, gas and/or magma. Both swarms were linked to changes in gas emissions. Increases in hydrogen concentration, and (R/Ra)c up to 7.52 ± 0.05, were recorded before the first swarm, at the sampling point closest to where seismicity was located, indicating a deep gas input. After the second swarm, increases in (R/Ra)c and thoron soil concentration were recorded at two locations. This dataset is compatible with a stalled magmatic intrusion at ca. 25 km depth, with an estimated volume between 5.5·10−4 km3 and 3·10−2 km3.
Time scales of open-system processes in a complex and heterogeneous mush-dominated plumbing system
(Geological Society of America, 2022-08-01) Spiess, Richard; Albert Mínguez, Helena; Trua, Teresa; Fonseca, José; Marani, Michael P.; Gamberi, Fabiano; Marzoli, Andrea
The architecture of a mush-dominated plumbing system in active volcanic areas conditions the magma pathways feeding eruptions. Open-system processes along these pathways and the associated time scales are directly related to monitoring data and eruptive behavior. Despite crystal mush–dominated systems being common in active volcanoes, previous studies have not focused on the integration of data from the mush sectors feeding different eruptions, supplying a partial view of the pre-eruptive magmatic processes and hindering the interpretation of the monitoring signals during unrest periods. We focus on the Marsili seamount (Tyrrhenian Sea), where the mineral data document processes within a magmatic system vertically extended throughout the local oceanic crust and made of a mush framework spotted with eruptible melt- and crystal-rich pockets. We undertook a study of Marsili olivine crystals that constrains the time scales of three pre-eruptive scenarios, dominated by open-system processes: (1) disaggregation of the deep Marsili volcano mush zone that occurred over a time scale of years prior to the eruption; (2) rapid ascent (days) of mantle-derived basaltic magma that, in some cases, intercepts shallow plagioclase-rich pockets; and (3) multiple mixing events between melt- and crystal-rich mush zones occurring approximately 1–2 mo and 0.5–3 yr before the eruption. Our results highlight the importance of contemporaneously studying eruptions in different locations on a volcano edifice for a better comprehension on how mush-dominated plumbing systems work as a whole and how this must be considered during the interpretation of monitoring data.
Magma interactions, crystal mush formation, and unrest during caldera collapse and lateral eruption at ocean island basaltic volcanoes (Piton de la Fournaise, La Réunion)
(Elsevier B.V., 2019) Albert Mínguez, Helena; Costa F.; Di Muro, A.; Herrin, J.; Métrich, N.; Deloule, E.
The dynamics of magmatic processes at large mafic ocean island volcanoes control the likely locations (central caldera versus flanks) and timing of their eruptions. Crystals and their melt inclusions are key witnesses of these processes but are rarely studied in detail and in the same samples. Here we report the crystal and melt inclusion compositions of the April 2007 caldera-forming eruption of Piton de la Fournaise volcano and discuss how they relate to geophysical unrest monitoring data. Olivine crystals show mainly normal zoning (decrease in Mg/Fe) towards the rims, and also around some melt inclusions. Many crystals also show fine-scale skeletal structures defined by high phosphorus concentrations. Melt inclusions contain 53–205 ppm CO2and 0.25–1.1 wt% H2O, and δD (δD values expressed as δDVSMOW) ranges from −135 to 62. Monitoring data show that inflation of the edifice started about a month before the first 2007 eruption: magma intrusion occurred at ≈3 km below sea level, and quickly migrated towards shallower depths (about 1 km above sea level). Such a time frame of magma movement is recorded in the chemical zoning of the olivine crystals that massively and quickly crystallized when reaching shallow depth, without significant interactions between resident and intruding magmas. The intrusion was followed by lateral flank eruption and caldera collapse. The chemical zoning of the olivine crystal rims and around the melt inclusions indicates that the newly created crystal-mush moved laterally towards the surface in matter of days to 3 months. Post-caldera samples show significant H+loss, likely due to the depressurization of the magmatic system stored at shallow level. Our findings are different from other mafic ocean island volcanoes or stratovolcanoes (e.g. Kilauea, Canary Islands, and Etna), where crystals commonly record magma mixing between evolved and shallow melts and intruding mafic melts. We speculate that the difference between our findings and those of similar mafic ocean island volcanoes is due to the variety of magma supply rates from depth.
Years to weeks of seismic unrest and magmatic intrusions precede monogenetic eruptions
(Geological Society of America, 2016) Marti Ribas, Josep; Costa, Fidel; Albert Mínguez, Helena
Seismic, deformation, and gas activity (unrest) typically precedes volcanic eruptions. Tracking the changes of this activity with monitoring data makes it increasingly possible to successfully forecast eruptions from stratovolcanoes. However, this is not the case for monogenetic volcanoes. Eruptions from these volcanoes tend to be small but are particularly difficult to anticipate since they occur at unexpected locations and there is very limited instrumental monitoring data. Many monogenetic volcanic fields occur in high-density, populated areas and/or tourist destinations, and thus even a small eruption can have a major economic and societal impact. We have gathered the available instrumental data for unrest and combined it with new historical accounts of seismicity. Our occurrences are mainly from high magmatic flux oceanic islands (Canary Islands, Iceland, Papua New Guinea, Mexico, and Japan). We find that seismic activity may start one or two years before eruption, but it intensifies at approximately two or three months, and one or two weeks. The petrological and geochemical characteristics of the deposits show that multiple magma batches interacted in a subvolcanic reservoir, and multiple intrusions occurred on a similar time scales to the seismicity. We propose a general model for these eruptions where early dike intrusions in the crust do not erupt (e.g., stalled intrusions) and make small plumbing systems, but they probably are key in creating a thermal and rheological pathway for later dikes to be able to reach the surface. These observations provide a conceptual framework for better anticipating monogenetic eruptions in similar settings and magmatic fluxes and should lead to improved strategies for mitigation of their associated hazards and risks.
Microbial mediation and climatic control on dolomiteprecipitation in a hypersaline lake: Insights from SalinasLake, southern Iberia
(John Wiley & Sons, 2025-12-12) Li, Guolai; Naim, Zeina; Gibert Beotas, Lluís; Stuut, Jan-Berend; Waajen, Annemiek C.; Jimenez-Moreno, Gonzalo; Sánchez-Román, Mónica
This study examines the climatic controls on dolomite precipitation through a multiproxy investigation of a carbonate-rich sediment core from Salinas Lake, a hypersaline playa in Alicante, south-eastern Iberia. The ~120,000 year record captures depositional cycles and palaeoenvironmental changes driven by late Pleistocene to Holocene climate variability. Integrated analyses of sedimentology, lithology, geochemistry (elemental concentrations, total organic carbon, stable carbon and oxygen isotopes), scanning electron microscopy, microbial community characterisation and palynology reconstruct lake hydrology and its influence on carbonate mineralogy. The sediment succession is marked by alternating calcite- and dolomite-rich intervals, with dolomite crystals displaying morphological evolution from spherical to rhombohedral forms with depth. Stable isotope signatures (δ13C: −6.5‰ to −2.4‰ VPDB; δ18O: −2.3‰ to +4.9‰ VPDB), alongside microbial structures such as extracellular polymeric substances (EPS) and internal crystal voids, suggest a biologically mediated precipitation mechanism. These mineralogical shifts closely correspond to rapid hydrological changes driven by Dansgaard–Oeschger climate oscillations, with dolomite formation favoured under arid, evaporative conditions that concentrate Mg and Ca ions and promote microbial mat development. Halophilic microbial communities, capable of catalysing carbonate precipitation, probably enhance dolomite nucleation and growth through EPS production and geochemical modulation. This work underscores the complex interplay between climate, hydrology, microbial activity and sedimentary mineral formation, providing new insights into the longstanding ‘dolomite problem’ within sedimentary environments.
Unveiling the complexity of monogenetic volcanic fields: a petrological exploration of the Puig Jordà (Garrotxa Volcanic Field, Spain).
(Oxford University Press, 2025-05-05) Albert Mínguez, Helena; Muir, Louise; Pedrazzi, Dario; Gisbert Pinto, Guillem; Bolós Granados, Xavier de; Geyer, Adelina; Aulinas Juncà, Meritxell
The magmas erupted in the Garrotxa Volcanic Field (GVF) in northeastern Spain have been traditionally attributed to direct ascent of magma from its source in the mantle, a theory supported by the frequent presence of mantle xenoliths in some eruptive products. However, recent petrological and geochemical studies of monogenetic eruptions in other volcanic fields have revealed the common existence of shallow magma pockets that are intercepted by new intruding magma before eruption. Consequently, different magma ascent timescales (direct vs. arrested) would have significant implications for the duration of potential pre-eruptive unrest in the GVF and, hence, for the interpretation of monitoring data. Here we report, for the first time, a detailed study of the mineral phases hosted in the magmas from the GVF. We have focused on the Puig Jordà monogenetic eruption (17 ka), located 3.5 km away from the city of Olot, and previously linked with a significant lava flow (Bosc de Tosca). We have conducted volcano-stratigraphic fieldwork followed by an extensive examination of the mineral phases to elucidate the magma plumbing system architecture. The eruptive sequence was characterised by Strombolian activity, with minor sporadic phreatomagmatic phases. The petrological and geochemical analyses of pyroxene, olivine, and spinel have revealed the occurrence of arrested magma intrusions preceding the eruption. Furthermore, our study has revealed that either the Bosc de Tosca lava flow is not sourced from this volcano or the eruption involved the emission of two distinct magmas: one led to the formation of the pyroclastic deposits, while the other produced the lavas. By comparison with other monogenetic volcanoes from the GVF, the first hypothesis seems more reliable. Thermobarometric modelling of pyroclasts suggests rapid magma ascent from a deep zone at approximately 900 to 1200 MPa and 1200°C to 1250°C, followed by the incorporation of previously emplaced magma batches located at 600 to 900 MPa and 1175 ± 15°C, and a final stage occurring at shallow crustal levels with lower temperatures (~120 MPa and 1110 ± 30°C). Our results show a complex ascent history in a multi-level plumbing system and have direct implications for the interpretation of future unrest episodes in this and other active monogenetic volcanic fields.
PWD: Petrology Workspace & Database
(Wiley, 2019) Schonwalder-Angel, Dayana; Albert Mínguez, Helena; Tuan, Lam Ngoc; Phi, Nguyen Xuan; Utami, Sri Budhi; Li, William; Khanh, Phung Minh; Widiwijayanti, Chirstina; Costa, Fidel
The Petrology Workspace and Database (PWD; https://petro.wovodat.org) is a web-based data repository and interface that allows researchers to access, share, store, and manage petrological, mineralogical, and whole rock data in a contextualized manner. The uniqueness of the PWD is that it links images to different types of images and to compositional data providing a powerful visualization and framework of information at a wide range of scales, from the meter-sized outcrop to a few micrometers of a thin rock section. The PWD archives various data types and formats, and it includes multilevel data sets with an interactive online interface. The database is linked with other databases for volcanic eruptions (Smithsonian' Global Volcanism Program (GVP)) and for whole rock chemistry (EarthChem). The tool has four main features: (1) storage and management of spatial-referenced data (e.g., from fieldwork notes to lab geochemical analysis); (2) a hierarchical relationship between different types of data using the Workspace interactive tool; (3) graph plots to visualize the data; and (4) the possibility of data sharing in a database structure that is managed by authorization levels. The PWD is a practical and efficient database management system that facilitates effective contextualized data preservation and sharing among scientists. It also can serve as a Data Management Plan and provide a framework for auditing research integrity both of which are becoming the new standards of most funding agencies and journals.
Mapping the Impact of Salinity Derived by Shrimp CulturePonds Using the Frequency-Domain EM Induction Method
(MDPI, 2025-10-07) Casas i Ponsatí, Albert; Beltrão-Sabadía, José A.; Sabino da Silva, Evanimek Bernardo; Monte-Egito, Lucila C.; Medeiros-Souza, Anderson de; Tapias Pantebre, Josefina Carlota; Sendros Brea-iglesias, Alexandre; Pinheiro Lima-Filho, Francisco
This study investigates groundwater salinization in a section of a coastal aquifer in RioGrande do Norte, Brazil, using frequency-domain electromagnetic (FDEM) measurements.With the global expansion of shrimp farming in ecologically sensitive coastal regions, thereis an urgent need to assess associated risks and promote sustainable management practices.A key concern is the prolonged flooding of shrimp ponds, which accelerates saltwaterinfiltration into surrounding areas. To better delineate salinization plumes, we analyzeddirect groundwater salinity measurements from 14 wells combined with 315 subsurfaceapparent conductivity measurements obtained using the FDEM method. Correlating thesedatasets improved the accuracy of salinity mapping, as evidenced by reduced variance inkriging interpolation. By integrating hydrogeological, hydrogeochemical, and geophysicalapproaches, this study provides a comprehensive characterization of groundwater salinityin the study area. Hydrogeological investigations delineated aquifer properties and flowdynamics; hydrogeochemical analyses identified salinity levels and water quality indicators;and geophysical surveys provided spatially extensive conductivity measurementsessential for detecting and mapping saline intrusions. The combined insights from thesemethodologies enable a more precise assessment of salinity sources and support the developmentof more effective groundwater management strategies. Our findings demonstratethe effectiveness of integrating geophysical surveys with hydrogeological and hydrogeochemicaldata, confirming that shrimp farm ponds are a significant source of groundwatercontamination. This combined methodology offers a low-impact, cost-effective approachthat can be applied to other coastal regions facing similar environmental challenges.
Mush system heterogeneities control magma composition and eruptive style on the Ocean Island of El Hierro, Canary Islands.
(Springer Verlag, 2025-04-23) Prieto-Torrell, Claudia; Albert Mínguez, Helena; Aulinas Juncà, Meritxell; González-Esvertit, Eloi; Arienzo, Ilena; Gisbert Pinto, Guillem; Troll, Valentin R.; Fernandez-Turiel, Jose-Luis; Rodriguez-Gonzalez, Alejandro; Perez-Torrado, Francisco-Jose
The study of recent eruptions in Ocean Islands (OIs) provides a unique window into the magma dynamics governing their plumbing systems and the mechanisms leading to eruptions. Here we present an integrated approach to unravel the dynamics of magmatic plumbing systems through detailed spatial, petrological, and geochemical characterisation of volcanic products ranging from crystal-rich ankaramitic lavas to trachytic tephras. We focus on the textural and geochemical spatial variations of 42 Holocene subaerial eruptions at the OI of El Hierro (Canary Islands), as well as on their petrogenetic significance for magmatic evolution and plumbing system architecture. Integrating geochemical data within fractional crystallisation modelling and mass balance calculations reveals that ankaramitic and porphyritic lavas with phenocryst modal abundances > 10 vol% result from melt extraction and crystal accumulation. Aphyric to sub-aphyric eruption products and porphyritic lavas with phenocryst modal abundances < 10 vol% usually follow fractional crystallisation trajectories that start at ~ 10 wt% MgO. Periodic extraction of evolved melt from crystal mushes likely led to the occurrence of minor trachytic eruptions, which are difficult to reconcile with simple closed system fractional crystallisation trends. A complex, heterogeneous crustal mush system beneath El Hierro is, in fact, the most reliable scenario to explain the wide range of textures, whole-rock and mineral compositions, and the overall surface distribution of vents and eruptive styles displayed by the Holocene volcanism on the island. Our integrated findings highlight the importance of a combined field, petrological, and geochemical study to decipher plumbing system dynamics of OI magmatism. The results allow us to put forward an updated conceptual model of the current plumbing architecture of El Hierro’s volcanic system during the Holocene.
CatVolc: A new database of geochemical and geochronological data of volcanic-related materials from the Catalan Volcanic Zone (Spain)
(Elsevier B.V., 2024-02-01) Miranda-Muruzábal, Martín; Geyer, Adelina; Aulinas Juncà, Meritxell; Albert Mínguez, Helena; Vilà, Miquel; Micheo, Fus; Bolós Granados, Xavier de; Pedrazzi, Dario; Gisbert Pinto, Guillem; Planagumà, Llorenç
The Catalan Volcanic Zone (CVZ) (NE Spain) consists of an intraplate alkaline volcanic zone associated with the opening of the Western Mediterranean and the development of the European Rift System. Volcanic activity in the CVZ started in the L'Empordà area (ca. > 12–8 Ma), extended to La Selva (7.9–1.7 Ma), and finally migrated to the Garrotxa Volcanic Field (< 0.7–0.01 Ma). Despite the scientific interest in the CVZ since the early 19th century, certain aspects remain poorly constrained. These include a full understanding of the spatial and temporal evolution of the magma plumbing system(s) and ascent mechanisms, as well as the chronology of volcanism across the CVZ. Addressing these unresolved questions requires geochemical, petrological, and geochronological data, which, in the case of the CVZ, are scattered and have never been integrated or analysed within a unified framework. Here, we present the CatVolc (Catalan Volcanism) database, which compiles available geochemical and geochronological data of volcanic-related materials from the CVZ. The current version of the database contains geochemical analyses from 405 rock samples (296 juvenile magmatic rocks -including lavas and pyroclasts- and 109 xenoliths), and radiometric/thermoluminescence dating data from 57 rocks (55 volcanogenic and two dykes), 4 paleosols samples developed between volcanic deposits and 1 sample from sediments. For each sample, the CatVolc database lists general information about the sampling site, sample lithology, whole-rock analyses (including major and trace elements), isotopic ratios, mineral chemistry, and radiometric/thermoluminescence dating information, if available. A preliminary analysis of the information contained in the CatVolc database highlights the critical limitations of the current state of knowledge and allows suggesting potential future directions for volcanic-driven investigations in the CVZ. Additionally, the results obtained validate the CatVolc database as a key tool for comprehending the spatial and temporal evolution of the magmatic system(s) and volcanic activity in the CVZ, particularly in the Garrotxa Volcanic Field. This aspect is critical for advancing in the assessment of the volcanic hazards in the region and for gaining a comprehensive understanding of future volcanic activity.
Time scales of olivine storage and transport as revealed by diffusion chronometry at Waitomokia Volcanic Complex, Auckland Volcanic Field, New Zealand.
(Elsevier B.V., 2024-07-01) Didonna, Rosa; Handley, Hearther; Albert Mínguez, Helena; Costa, Fidel
Detailed knowledge of the pre-eruptive time scales associated with magma storage and transport is vital to improve volcanic hazard forecasting in active volcanic regions. However, quantification of the timescales of volcanic processes at mafic volcanic centres in continental intraplate settings is challenging, despite them being a source of significant hazards for human populations and infrastructure due to their limited predictability in space and time. We conducted a detailed petrological study to investigate the time scales of olivine storage and transfer throughout the eruption sequence of Waitomokia Volcanic Complex, a tuff ring and scoria cone complex in the Auckland Volcanic Field. Olivine crystal textures and compositions were determined from stratigraphically-constrained samples of the volcanic complex, from the initial phreatomagmatic phase to the final magmatic phase. Olivine crystals are typically <300 μm in length and characterised by skeletal morphologies, displaying chemical zoning in forsterite (Fo = 100*Mg/[Mg + Fe]; mol%), CaO, MnO and NiO wt% contents. We classified olivine into three major groups based on their Fo core compositions: (1) normally zoned crystals with high Fo content (Fo > 85), (2) crystals with intermediate Fo contents (84–81), and (3) reversely zoned crystals with lower Fo core content (<80). Olivine chemical zoning (diffusion) profiles were modelled in the context of a specific magmatic environment linked with changes in thermodynamic variables during storage (temperature, pressure, and oxygen fugacity). We propose that the normally zoned olivine crystals grew in one magmatic environment (ME1), which subsequently intruded into a more evolved (lower MgO) environment (ME2), where they interacted and were stored for up to 135 days before their eruption. During magma ascent to the surface, a second magma mixing event occurred between ME2 and magma within a third magmatic environment (ME3), forming reversely-zoned olivine crystals yielding notably shorter ascent times of approximately a few days. The rocks from the opening phreatomagmatic phase of the eruption show a larger range in olivine group types compared to the final magmatic phase, where those from the deeper ME1 are more abundant. The short time scales of magma transport obtained in our study, on the order of days to months, should be informative of the warning times that may be encountered between the onset of volcanic unrest and an eruption in the Auckland Volcanic Field.
101 contact twins in gypsum experimentally obtained from calcium carbonate enriched solutions: mineralogical implications for natural gypsum deposits.
(International Union of Crystallography, 2023-04-13) Cotellucci A.; Otálora F.; Canals i Sabaté, Àngels; Criado-Reyes J.; Pellegrino L.; Bruno M.; Aquilano D.; Garcia-Ruiz JM.; Dela Pierre F.; Pastero L.
Gypsum twins are frequently observed in nature, triggered by a wide array of impurities that are present in their depositional environments and that may exert a critical role in the selection of different twin laws. Identifying the impurities able to promote the selection of specific twin laws has relevance for geological studies aimed at interpreting the gypsum depositional environments in ancient and modern deposits. Here, the effect of calcium carbonate (CaCO 3) on gypsum (CaSO 4 2H 2O) growth morphology has been investigated by performing temperature-controlled laboratory experiments with and without the addition of carbonate ions. The precipitation of twinned gypsum crystals has been achieved experimentally (101 contact twin law) by adding carbonate to the solution, and the involvement of rapidcreekite (Ca 2SO 4 CO 3 4H 2O) in selecting the 101 gypsum contact twin law was supported, suggesting an epitaxial mechanism. Moreover, the occurrence of 101 gypsum contact twins in nature has been suggested by comparing the natural gypsum twin morphologies observed in evaporitic environments with those obtained in experiments. Finally, both orientations of the primary fluid inclusions (of the negative crystal shape) with respect to the twin plane and the main elongation of sub-crystals that form the twin are proposed as a fast and useful method (especially in geological samples) to distinguish between the 100 and 101 twin laws. The results of this study provide new insights into the mineralogical implications of twinned gypsum crystals and their potential as a tool to better understand natural gypsum deposits.
Mechanisms shaping the gypsum stromatolite-like structures in the Salar de Llamara (Atacama Desert, Chile)
(Nature Publishing Group, 2023-01-12) Criado-Reyes, Joaquín; Otálora, Fermín; Canals i Sabaté, Àngels; Verdugo-Escamilla, Cristóbal; García-Ruiz, Juan-Manuel
The explanation of the origin of microbialites and specifically stromatolitic structures is a problem ofhigh relevance for decoding past sedimentary environments and deciphering the biogenicity of the oldest plausible remnants of life. We have investigated the morphogenesis of gypsum stromatolitelikestructures currently growing in shallow ponds (puquíos) in the Salar de Llamara (Atacama Desert, Northern Chile). The crystal size, aspect ratio, and orientation distributions of gypsum crystals within the structures have been quantified and show indications for episodic nucleation and competitive growth of millimetric to centimetric selenite crystals into a radial, branched, and loosely cemented aggregate. The morphogenetical process is explained by the existence of a stable vertical salinity gradient in the ponds. Due to the non-linear dependency of gypsum solubility as a function of sodium chloride concentration, the salinity gradient produces undersaturated solutions, which dissolve gypsum crystals. This dissolution happens at a certain depth, narrowing the lower part of the structures, and producing their stromatolite-like morphology. We have tested this novel mechanism experimentally, simulating the effective dissolution of gypsum crystals in stratified ponds, thus providing a purely abiotic mechanism for these stromatolite-like structures.
Gypsum Crystals Formed by the Anhydrite–Gypsum Transformation at Low Temperatures: Implications for the Formation of the Geode of Pulpí
(MDPI, 2024-11-01) Cotellucci, Andrea; Garcia-Ruiz, Juan-Manuel; Otálora, Fermín; Canals i Sabaté, Àngels; Bruno, Marco; Wehrung, Quentin; Pellegrino, Luca; Aquilano, Dino; Pastero, Linda
Determining the mechanisms of the formation of giant crystals is a challenging subject. Gypsum, calcium sulfate dihydrate (CaSO4·2H2O), is known to form crystals larger than one meter in several locations worldwide. These selenite crystals grow at different temperatures, either in sedimentary or hydrothermal systems. The famous selenite crystals of the geode of Pulpí (Almería, Spain) are known to have grown at a temperature T = 20 ± 5 ◦C and have been proposed to form in a subaqueous environment by a self-feeding mechanism triggered by anhydrite dissolution and the ripening of microcrystalline gypsum, enhanced by oscillations in temperature. This paper reports the monitored crystallization of gypsum crystals, from anhydrite powder dissolution, inside airtight evaporation-free reactors under oscillating low temperatures (15 ◦C < T < 25 ◦C). These crystals are clearly smaller than the ones in the Pulpí mine but exhibit similar habits (i.e., single blocky crystals and twins following the 100 twinning law). The growth rate of gypsum single crystals has been measured to be between 3.8 and 35.3 μm/day. Noteworthy, we document the occurrence of the 100 contact twinning law of gypsum, which is the most widespread twinning law in natural environments but never univocally reported in laboratory experiments. The selection of the 100 contact twinning law has been correlated to the low supersaturation values obtained in the experiment, where the concentration in these long-duration experiments can be safely assumed to be the equilibrium concentration, i.e., 0.3 (at 25 ◦C) ≤ SI ≤ 0.4 (at 15 ◦C).We discuss the relevance of our experiment for forming the gypsum crystals of Pulpí in the framework of the geological history of Pulpí mineralization. These laboratory model experiments contribute to a deeper understanding of mineral nucleation and growth processes in natural environments.
Hydrolytic weakening controls Jurassic to early Cretaceous mylonitization in the basement of the Pyrenees
(Elsevier Ltd., 2026-02-01) Domínguez-Carretero, Diego; González-Esvertit, Eloi; Casas Tuset, Josep Maria; Canals i Sabaté, Àngels; Bons, Paul D.; Konrad, Kevin; Llorens, Maria-Gema; Serrano-López, Gabriel; Claudia Prieto-Torrell; Neilson, Joyce; Beranoaguirre, Arants; Gerdes, Axel; Gómez Rivas, Enrique
The age of the mylonite belts in the basement rocks of the Pyrenees is a subject of debate in the structural geology and petrology communities because of its potential implication on the regional tectonothermal history and on the tectonic evolution of SW Europe. Here we address when and how mylonitisation took place in two key areas of the Eastern Pyrenees, where shear zones are associated with Giant Quartz Veins (GQVs). We conducted zircon U-Pb and muscovite 40Ar/39Ar dating coupled with structural, textural, and crystallographic preferred orientation (CPO) analyses of mylonites from the Cap de Creus and Canigó Massifs. U-Pb zircon dating of a dacite porphyry dyke crosscut by GQVs and mylonitic bands yields a maximum shear zone and GQV formation age of ca. 292 ± 3 Ma. 40Ar/39Ar analyses of muscovite within mylonitised GQVs yield initial crystallisation ages between ca. 164 and 188 Ma, as well as younger recrystallisation ages of ca. 110–118 Ma. A qualitative assessment of the GQV history is inferred from step-heating spectra of muscovite and quartz CPOs. The results indicate that GQV formation and mylonitisation were coupled, coeval, and long-lasting processes that took place from early Jurassic to early Cretaceous times. A comparative evaluation of quartz CPOs reveals inconsistencies regarding the strain distribution, quartz slip systems activity, and deformation temperatures depending on the deformed rock type. Quartz mylonites have stronger CPOs dominated by basal , prism , or prism slip systems, whilst phyllonites and granite mylonites show weaker fabrics mostly dominated by mixed slip. This apparently suggests higher deformation temperatures in quartz mylonites than those inferred from more reliable proxies, such as mineral assemblages, brittle behaviour of K-feldspar, and fluid inclusion data. We suggest that the water-weakening effect caused by coeval formation and deformation of GQVs enabled easier dislocation glide and creep, allowing strain localisation and transitions between slip systems at lower temperatures than commonly inferred due to enhanced ductility. U-Pb zircon dating further suggests the existence of an early Carboniferous (ca. 332 ± 4 Ma; Visean) magmatic episode in the Pyrenees, in agreement with a cyclic, rather than a progressive, geodynamic history of the region during Variscan times. The present work challenges classical interpretations stating that Pyrenean mylonite belts developed during the retrograde stages of the Variscan Orogeny, highlighting that the structural evolution of this region during Mesozoic times deserves further investigation. Results have implications for interpreting deformation localisation mechanisms and conditions in crustal rocks, for the formation mechanisms of GQVs in worldwide orogenic belts, and for the tectonothermal history of the Pyrenees since late-Variscan times.

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