Felipe González

Mining activities in the Iberian Pyrite Belt have generated large volumes of legacy wastes that may pose both environmental and radiological concerns, potentially limiting their reuse and valorization. However, integrated assessments combining chemical, mineralogical, and radiological characterization of these materials remain scarce. In this work, representative mining wastes from twelve sites across the Iberian Pyrite Belt were investigated through X-ray fluorescence, X-ray diffraction, scanning electron microscopy, standardized leaching tests, alpha and gamma spectrometry, and radon emanation measurements. The results revealed significant enrichment in potentially toxic elements, particularly Cu, Zn, Pb, and As, with concentrations exceeding local soil background values by up to several orders of magnitude. Leaching tests identified oxidized sulfide-rich residues as the materials with the highest pollutant mobility and greatest acid-generating potential. In contrast, radiological characterization showed that uranium-series, thorium-series radionuclides, and ⁴⁰K activities, together with radiological hazard indices and radon exhalation rates, were generally comparable to those of surrounding natural soils and remained below internationally recommended limits. These findings indicate that chemical contamination represents the main environmental constraint of these wastes, whereas radiological impact is generally low, supporting their case-by-case evaluation for remediation, valorization, and potential exclusion from radiological control.

The Iberian Pyrite Belt contains one of the largest accumulations of massive sulphide deposits on Earth. Many of these deposits are hosted by latest Devonian black shales rich in terrestrial and marine palynomorphs. Among the marine fossils, the most abundantly reported species is Maranhites mosesii. By means of a multi-analytical methodology, including (1) biometry of specimens, (2) TOFSIMS imaging and spectral analysis of selected specimens and (3) host-rock geochemistry, we detected that cysts of M. mosesii are smaller and lighter in massive sulphide-generating environments than in coeval non-massive sulphide-generating environment. Cysts of M. mosesii sank after encystment and maturated in the seafloor of different subbasins affected by disparate anoxic conditions. The specimens that maturated in anoxic settings enriched in pollutants, like Arsenic (As) and Lead (Pb), were smaller and lighter than those from non-polluted anoxic environments. Their organic walls were also enriched in As. Neither the anoxia nor the pollutants prevented the proliferation of M. mosesii, as this was the most abundant phytoplanktonic species in all environments. To explain this, we suggest that this species developed a successful adaptive mechanism that might involve anaerobic metabolic interchange with the surrounding oxygen-depleted media and high levels of tolerance to stressors. Whatever the reason, it entails a causal relationship between cyst size and seafloor environmental conditions. In consequence, the biometry of M. mosesii can be envisaged as a promising vector for sulphide deposit exploration in the Iberian Pyrite Belt.

In the energy transition era, the supply risk of critical raw materials (CRMs) must be addressed with strategic efficiency and expertise to address the pressing challenges of climate change, increasing resource demands and to support the objectives of the European Green Deal. Strengthening local production and promoting the sustainable management of CRMs is essential to reduce reliance on imports and ensure a resilient supply chain.As the emphasis on sustainable resource practices increases, the demand for skilled professionals to oversee the responsible and secure extraction of these materials is increasing. However, a major challenge in Europe is the shortage of qualified professionals in the mining and mineral resources sector. Universities have been identified as playing a pivotal role in addressing the deficit in professional training by adopting innovative learning and teaching methods. The integration of advanced digitization technologies into educational frameworks is a key aspect of this, ensuring that students are equipped with the knowledge and skills necessary to support the sustainable development of the mining industry.The IMMERSE (Immersive Virtual Tours on Critical Minerals for Clean Energy Transition) project constitutes an innovative educational initiative focused on the development of Virtual Excursions (VEs) to enhance learning in the CRMs sector. This collaborative project brings together leading universities from Europe and Australia to address the skills gap in mining and geoscience training by employing cutting-edge teaching approaches that prioritize sustainability.The VEs serve as cutting-edge educational tools that allow students to safely engage with scenarios that are otherwise difficult to access or present safety concerns in real-world environments. By replicating real mining environments through immersive online experiences, VEs allow students to explore ongoing research and industry practices without the constraints of geography. These virtual platforms encourage the exploration of sustainable practices and innovative solutions to today's mining challenges, aligning educational goals with industry needs. The realisation of the IMMERSE project has been made possible by funding from the ERASMUS+ grant programme of the European Union (grant number: 2023-1-DE01-KA220-HED-000165332). We are deeply grateful for their invaluable support, which has enabled us to undertake this important endeavour. Their commitment to promoting educational initiatives and intercultural exchange has been instrumental in shaping the trajectory of our project and empowering us to make meaningful contributions to our field.

The Iberian Pyrite Belt (IPB) represents one of the largest districts of volcanogenic massive sulfide (VMS) deposits in the world, and is a critical source of base metals (Cu, Pb, and Zn) for Europe. Confirmed resources exceed 1700 Mt of massive sulfides with grades of around 1.2% Cu, 1% Pb, and 3% Zn as well as more than 300 Mt of stockwork-type copper mineralization. Significant resources of Sn, precious metals (Au and Ag), and critical metals (Co, Bi, Sb, In, and Se) have also been evaluated. The genesis of these deposits is related to a complex geological evolution during the late Devonian and Mississippian periods. The geological record of such evolution is represented by three main lithological units: Phyllite–Quartzite Group, the volcano–sedimentary Complex (VSC), and the so-called Culm Group. The sulfide deposits are located in the VSC, associated with felsic volcanic rocks or sedimentary rocks such as black shales. The massive sulfide deposits occur as tabular bodies and replacement masses associated with both volcanic and sedimentary rocks. Their mineralogical composition is relatively simple, dominated by pyrite, chalcopyrite, sphalerite, and galena. Their origin is related to three evolutionary stages at increasing temperatures, and a subsequent stage associated with the Variscan deformation. The present paper summarizes the latest developments in the IPB and revises research areas requiring further investigation.

Close to the city of Huelva, SW Spain, and near the Atlantic Ocean, there is a phosphogypsum (PG) stack that accumulates 100 Mt of wastes and extends over 1000 ha. The stack lies directly over estuarine unconsolidated sediments with no protective layer in between. Here, we evaluate for the first time the structural stability of the PG stack, monitoring the deformation suffered by the salt-marsh basement. Through the web-based Geohazard Exploitation Platform (GEP) of the European Space Agency (ESA), a specific differential SAR interferometry (DInSAR) algorithm known as Parallel Small Baseline Subset (P-SBAS) has been used to process 279 ESA Sentinel-1 images acquired between October 2016 and June 2021. Resulting displacement maps and time-series curves reveal vertical displacements of up to 16 cm/year. This vertical motion has been associated to subsidence. In parallel with subsidence, horizontal movements > 2.5 cm/year have been also accounted and linked to talus destabilization. The analysis also demonstrates that the Huelva PG stack is vulnerable to adverse weather condition. The present study demonstrates that the InSAR-based methods are effective tools for monitoring the stability and ground motion of large waste stockpiles.

A new early Visean coral assemblage has been recorded from turbidite facies in the southern part of the Azrou-Khenifra Basin, northwest of Khenifra, central Morocco. The newly discovered Ba Moussa West (BMW) coral fauna includesSiphonophyllia khenifrensesp. nov.,Sychnoelasma urbanowitschi,Cravenia lamellata,Cravenia tela,Cravenia rhytoides,Turnacipora megastomaandPleurosiphonella crustosa. The early Visean age of the coral assemblage is supported by foraminiferal and conodont data, with the recognition of the basal Visean MFZ9 Zone. This confirms that the first transgression in the Azrou-Khenifra Basin was during the earliest Visean. The allochthonous coral assemblage was recovered from coarse-grained proximal limestone debris flow and turbidite beds within a fault-bounded unit, lying to the west of a thrust syncline containing upper Visean limestones. No evidence exists of the former early Visean shallow-water platform from which the corals were derived. All other in situ platform carbonate rocks around the southern margin of the Azrou-Khenifra Basin are probably of late Visean (Asbian–Brigantian) age. The early Visean Ba Moussa West coral fauna can be compared with that at Tafilalt in eastern Morocco, as well as in other Saharian basins of Algeria. Many of the genera and species in the Ba Moussa West assemblage are identical to those in NW Europe, with which it must have had marine connections. The new rugose species described,Siphonophyllia khenifrense,is probably endemic to North Africa. Its ecological niche in NW Europe was occupied byS. cylindricaorS.aff.garwoodi.

The Iberian Pyrite Belt (IPB) is recognized as having one of the major concentrations of volcanogenic massive sulfide (VMS) deposits on Earth. Original resources of about 2000 Mt of massive sulfides have been reported in the province. Recent classifications have considered the IPB deposits as the bimodal siliciclastic subtype, although major differences can be recognized among them. The main ones concern the hosting rocks. To the north, volcanic and volcaniclastic depositional environments predominate, whereas to the south, black shale-hosted VMS prevail. The mineral composition is quite simple, with pyrite as the main mineral phase, and sphalerite, galena, and chalcopyrite as major components. A suite of minor minerals is also present, including arsenopyrite, tetrahedrite–tennantite, cobaltite, Sb–As–Bi sulfosalts, gold, and electrum. Common oxidized phases include magnetite, hematite, cassiterite, and barite. The spatial relationship between all these minerals provides a very rich textural framework. A careful textural analysis reported here leads to a general model for the genetic evolution of the IPB massive sulfides, including four main stages: (1) Sedimentary/diagenetic replacement process on hosting rocks; (2) sulfides recrystallization at rising temperature; (3) metal distillation and sulfides maturation related to late Sb-bearing hydrothermal fluids; and (4) metal remobilization associated with the Variscan tectonism. The proposed model can provide new tools for mineral exploration as well as for mining and metallurgy.

The Rammelsberg sulfide deposit is classically considered as a SEDEX-type deposit. The origin of SEDEX-type massive sulfides links with the evolution of their hosting basins. They frequently constitute the source for the metal-enriched basinal brines transported afterwards as mineralizing hydrothermal fluids. This study revisits previous data concerning the analysis of the basin that hosts the Rammelsberg deposit, the Goslar basin, updating its subsidence analysis and providing new tectonic and total subsidence curves from two different paleogeographic locations: the depocenter and the basin margin. The basin evolution is defined by five stages depicting different subsidence intensity and mechanisms for each of these locations. The stratigraphic position of Rammelsberg coincides with a drastic change in the basin evolution. A rapid tectonic subsidence event is proposed as a trigger mechanism for hydrothermal activity. The paleogeographic location and the relation between supply of mineralizing fluids and sedimentation rate were critical for the concentration or dissemination of sulfides.

This study, conducted in the Catalan Coastal Ranges, north‐east Spain, describes the Upper Devonian Kellwasser event in a shallowing‐upward sequence of black shales, siltstones and quartz arenites. This sequence was deposited in a progradational and regressive coastal system where the sedimentary environment evolved from the inner shelf to a lagoonal pond located landward of the shoreline. Three anomalous succeeding steps have been identified by geochemical analysis. The first one, detected on the inner shelf, was characterized by oxygen depletion and high organic productivity. The second, detected in the nearshore, was caused by hydrothermal activity occurring under normal oxic conditions. The third and most intense step was identified in the muds of the lagoonal pond and has been linked to strong anoxic conditions, elevated clastic input derived from changes in the weathering regime at the source area and moderate hydrothermal activity. The Kellwasser event is thus defined in the study area as stepwise and multi‐causal. This is the first time that the Kellwasser event has been identified in a sedimentary environment behind the shoreline. It is also the first time that it has been reported in the Catalan Coastal Ranges.

Coal‐forming environments require humid to perhumid conditions. Tectonics governs the size, location and availability of coal seams developed in such environments. While large Pennsylvanian paralic basins generated thick and continuous coal seams, many other small coeval basins, which were tectonically active, developed a puzzling succession, with carbonaceous deposits that varied in size, thickness and the nature of the coal‐forming flora. This study, conducted in the Peñarroya‐Belmez‐Espiel coalfield, a Variscan strike‐slip basin in the south of Spain, provides insights into this subject. The coal seams analysed, generated in different depositional environments, have quantitatively different palynological assemblages. Lacustrine coals are dominated by lycopsids; distal alluvial plain/marginal lacustrine coals are dominated by sphenophytes and tree ferns, and middle alluvial fan coals are dominated by sphenophytes, tree ferns and lycopsids. This means that when conditions were favourable for peat accumulation, peat accumulated regardless of the nature of the available flora.