Instituto Geológico y Minero de España

Detailed geological mapping of a highly fractured Paleozoic basement and the scarce outcrops of overlying Permian-Mesozoic cover in the surroundings of the Duje Valley (Picos de Europa Unit, Cantabrian Mountains, NW Spain), together with new field data have allowed the separation of four genetic fault sets in a polyorogenic area, affected by the Variscan and Alpine cycles. These fault sets are, from oldest to youngest: Variscan thrusts (late Carboniferous), Late Variscan strike-slip faults (late Carboniferous–earliest Permian), Alpine normal faults (Permian–Mesozoic) and Alpine reverse faults (Cenozoic). A structural analysis is reported here, based in the joint use of geometric, kinematic and deformational features, crosscutting and tectono-sedimentary relationships between the structures. This analysis has allowed the recognition and full characterization of the four fault sets. These types of structural analyses are useful for unravelling complex tectonic histories in regions where massive limestone lithologies make reconstructing the timing of fault activity difficult, especially if the basement is affected by late deformation events that are not recorded by cover outcrops.

The evolution of the Gondwana along the flank of the West African Craton was complex and is far from understood. Subduction-related activity along this margin spanned between c. 750 and 500 Ma. Sections close to African cratons record the earliest stages, while Autochthonous and Allochthonous domains of the Variscan Belt preserve the latest stages of the arc system, essentially between c. 540 and 500 Ma. The geochemistry of the Ediacaran-early Cambrian siliciclastic series deposited along this Cadomian active margin preserves the evolutionary history of their sources, which are related to activity in the arc and nearby continental areas. In this sense, the SW Iberian Massif (Ossa-Morena Complex) preserves a section of this Ediacaran-early Cambrian peri-Gondwanan arc. Its evolution can be tracked through the characterization of the subduction-related magmatism (including the Mérida Massif) and coeval metasedimentary record (Serie Negra Group and Malcocinado Formation) during a time interval spanning almost 100 m.y., from pre-602 Ma to at least c. 534 Ma. This study reveals that arc magmatism is closely linked with synorogenic deposition in a complex way so far unexplored. Arc recycling is revealed by the isotopic equivalence of synorogenic strata to the first magmatic event (pre-602 Ma), and by geochronological data of the arc-building pulses. The earliest magmatic pulses (c. 602–550 Ma) are characterized by significant crustal input, likely favoured by subduction erosion. Subsequently, magmatism evolved towards larger mantle involvement (c. 540–534 Ma), likely associated with progressive variation in the slab angle. These slab-mantle-upper plate interactions generated changes in the arc dynamics leading to an extensional setting with alkaline magmatism during the Cambrian. This review proposes a model of petrogenetic and geodynamic arc evolution between the Ediacaran and the Early Cambrian. The gathered data could improve the accuracy of future palaeogeographic reconstructions for the northern margin of Gondwana.

This paper investigates the relationship between rainfall, groundwater and Gravity Recovery and Climate Experiment (GRACE) data to generate regional-scale estimates of terrestrial water storage variations in the Andalucía region of southern Spain. These estimates can provide information on groundwater depletion (caused by periods of low rainfall or droughts) and groundwater recovery. The spatial distribution of groundwater bodies in southern Spain is complex and current in situ groundwater monitoring methods are deficient, particularly in terms of obtaining representative samples and in implementing and maintaining groundwater monitoring networks. The alternative approach proposed here is to investigate the relationship between precipitation time series and changes in the terrestrial water storage estimated from GRACE observations. The results were validated against the estimated fluctuation in regional groundwater. The maximum correlation between the mean groundwater level and the GRACE observations is 0.69 and this occurs at a lag of one month because the variation in gravity is immediate, but rainfall water requires around one month to travel across the vadose zone before it reaches the groundwater table. Using graphical methods of accumulated deviations from the mean, we show that, in general, groundwater storage follows the smooth, multi-year trends of terrestrial water storage but with less short-term trends; the same is true of rainfall, for which the local trends are more pronounced. There is hysteresis-like behaviour in the variations in terrestrial water storage and in the variations of groundwater. In practical terms, this study shows that, despite the abnormal dryness of the Iberian Peninsula during the 2004–2010 drought, the depleted groundwater storage in Andalucía recovered almost to its pre-drought level by 2016. In addition, groundwater storage and terrestrial water storage show very similar trends but with a delay in the groundwater trend.

After the success of the first two editions of the Palaeontological Virtual Congress in 2019 (first PVC) and 2021 (second PVC; Crespo & Manzanares 2019; Crespo & Citton 2021), we have decided to try to replicate the success with a third meeting of the PVC (Fig. 1). The appearance of new applications and technological advances has played a crucial role in paving the way for enhanced avenues of effective scientific communication. This became even more pronounced from more than two years of challenges stemming from the COVID-19 pandemic. Due to this crisis, online platforms gained more relevance and proved key to keeping up the drive for science communication and the dissemination of scientific results (Barral 2020).

This work is focused on the Almonte‐Marismas aquifer located within Doñana Natural Space (SW Spain); this aquifer is threatened by droughts, irrigation‐driven groundwater overexploitation, urban use, and the potential reactivation of gas extraction and storage projects. We present ground deformation measurements from Sentinel‐1 Interferometric Synthetic Aperture Radar (InSAR) data ranging from 1‐2.5 cm, covering ∼2,500 km ² from 2014‐2020. Detecting spatially distributed ground deformation over this agricultural area is challenging due to the low‐coherence radar signals; consequently, the ground movement results are on the same order of magnitude as the errors associated with InSAR data. We have approached this issue by considering auxiliary information such as groundwater levels, climatic time series, and pumping rates and analyzing their spatio‐temporal connections to ground displacements. We correlate InSAR and hydrogeological information through wavelet analysis, developing a Python package that allows applying the same methodology in other similar study areas. For the first time in the Doñana area, a significant relationship between distances to pumping wells and the displacement extent is detected. Moreover, other subsidence‐related triggering factors are identified, such as the soil moisture balance, clay shrinking‐swelling processes, and creep of geological formations. These results are highly valuable to support aquifer management decisions in the Doñana Natural Space; in this border region, three groundwater bodies were officially declared overexploited in 2020. Our findings provide a ground motion baseline assessment to help differentiate historical variations from any future anthropogenic effect in this complex marsh land ecosystem.

The tectonic map at scale 1:1,750,000 presented in this work shows an update of the existing knowledge of the main tectonic and volcanic structures along the Iberian continental margins and abyssal plains. The morphotectonic trends around Iberia recorded superposed geodynamic processes linked to the opening of the North Atlantic Ocean since the Mesozoic and the evolution of the Mediterranean Sea during the Cenozoic, as well as the reactivation of Hercynian faults and the formation of new tectonic structures during the Alpine orogeny. This map is based on the interpretation of the digital bathymetric model and other geophysical data from our own studies, and those from other authors. The morphotectonic features in this map provides a basis for the recognition of the tectonic control at lithospheric plate scale and the establishment of potential tectonic and volcanic risk zones.

The protection of groundwater resources in coastal aquifers is an increasingly important issue worldwide. To establish threshold values and remediation objectives, it is essential to know the natural background concentrations of relevant ions in groundwater. The rationale is to define the Natural Background Level (NBL) of chemical species determined by atmospheric and lithological forces. In many coastal aquifers, this evaluation worsens since atmospheric and lithological salinity combines with many other anthropogenic sources of salinity, including exogenous salinity induced by seawater intrusion (SWI). This paper presents a combination of six well-known statistical techniques and a new methodology (i.e., SITE index) in eight GWBs affected by SWI in Eastern Spain. The chloride ion was the selected conservative chemical specie to assess the qualitative status due to the variable SWI affection. The Natural Chloride Background (NCB) obtained from these methodologies at the GWB scale was compared with regional NCB data calculated with the Atmospheric Chloride Mass Balance (CMB) method in Continental Spain. The CMB method provides atmospherically derived NCB data that are not influenced by SWI or anthropogenic activities or lithological forces. This external evaluation can be considered the atmospheric fraction of NCB, which serves as a regional criterion to validate the more detailed statistical methodologies applied at the GWB scale. As a result, a conceptualization of NCB is obtained by means of a range of values between 115 mg L−1 and 261 mg L−1 in the studied coastal GWBs affected by SWI in Eastern Spain.

Citation: Altolaguirre, Y.; Postigo-Mijarra, J.M.; Casas-Gallego, M.; Moreno-Domínguez, R.; Barrón, E. Mapping the Late Miocene Pyrenean Abstract: The Late Miocene palaeofloras of the La Cerdanya Basin represent a unique look into the Pyrenean Miocene forested areas of the Iberian Peninsula at a time when the European warm and humid climate was experiencing progressive cooling and aridification. Macrofossils (leaves, seeds, fruits and cones) and miospores from several outcrops revealed the composition and abundances of the different plant species present in the area during the Tortonian and early Messinian geological stages (ca. 11.1-5.7 Ma). These fossils were found in the sediment deposits of an ancient lake system situated in the southwestern part of the basin. Previous studies indicated the presence of highly diversified mixed mesophytic forests with broadleaved evergreen and deciduous trees and conifers. However, the spatial structure and distribution of these forest types remains unknown. In the present work, the biomization method was used to infer the different late Miocene vegetation types from the basin. The extent of these vegetation types was calculated using a methodology for mapping vegetation units from fossil and biome data. While previous attempts at mapping Miocene vegetation units had a broad geographical scale, the present work aimed to map the extent of the vegetation units at a small scale, recreating local and specific vegetation changes in an abrupt basin. Results showed similarly high scores between for four biome types, which represent the different types of vegetation that coexisted in the basin during the Tortonian and the early Messinian: warm-temperate evergreen broadleaf and mixed woodlands (WTEM biome), temperate deciduous forests (TEDE) and cool conifer forests (COMX and COEG). Their extent was depicted in two vegetation maps, which account for differences in palaeoaltitude and palaeoclimate. These forests occupied different vegetation belts, which shifted upwards and downwards with climatic variations and the progressive uplift of the Pyrenees during the late Miocene. Azonal riparian forests and wetland vegetation occupied the more humid areas in the centre of the basin. Nonetheless, dry conditions during the early Messinian and decrease in the lake area degraded the wetland environments, which were partially replaced by broadleaved evergreen mixed woodlands.

Understanding the drivers of the onset, evolution, and end of eruptions and their impact on eruption style is critical in eruption forecasting and emergency management. The composition of erupted liquids is a key piece of the volcano puzzle, but untangling subtle melt variations remains an analytical challenge. Here, we apply rapid, high-resolution matrix geochemical analysis on samples of known eruption date spanning the entire 2021 La Palma eruption. Sr isotope signatures reveal distinct pulses of basanite melt driving the onset, restart, and evolution of the eruption. Elemental variations in matrix and microcrysts track progressive invasion, and draining, of a subcrustal crystal mush. Associated variations in lava flow rate, vent development, seismicity, and SO2 emission demonstrate that volcanic matrix resolves eruption patterns that could be expected in future basaltic eruptions globally.

The Cambrian Atlas – Ossa-Morena – Northarmorican Rift extended along West Gondwana from the end of the Pan-African and Cadomian orogenies until the diachronous beginning of drift conditions related to the opening of the Rheic Ocean. The along-axis rift crosscut the western parts of the Anti-Atlas, High Atlas and Coastal Meseta, which were linked to the Ossa-Morena Zone and the North-Armorican Domain, whereas several joint tectonic branches connected with off-axis rift transects of the Central Iberian, West Asturian-Leonese and Cantabrian Zones (Iberian Massif), Central and Southern Armorican Domains, Occitan Domain, Pyrenees and southern Sardinia. The pre-rift unconformity, post-dating the orogenic collapse, is characterized by initial (half-)graben development and subsequent infill with slope-related breccias and conglomerates controlled by the denudation of surrounding uplands. Syn-rift pulses show regional extension and are distinctly identifiable on the top of rift shoulders recording episodes of carbonate production due to their association with karst and hydrothermal processes. The break-up unconformity ranges from volcanic-free angular discordances and paraconformities to generalized uplift and denudation of subaerially exposed areas, associated with the onset of granite-dominant LIPs. The Furongian–Tremadocian (Toledanian) and Ordovician (Sardic) Phases have been interpreted as due to (i) Andean-type subduction magmatism reaching the crust in an arc-to-back-arc setting, (ii) post-collisional decompression melting without significant mantle involvement, and (iii) partial melting of the lower continental crust affected by the underplating of hot mafic magmas linked to superplumes.

Polymetallic nodules, also called manganese nodules (due to their high content of this element), contain various valuable metals such as Cu, Ni and Co. These seabed minerals are a good alternative source of Co and Mn due to the decrease in the grade of mineral deposits on the earth's surface. For the treatment of manganese nodules, acid-reducing leaching is apparently the most attractive, due to its low cost compared to other processes, short operational times, and it is more friendly to the environment. In this investigation, the extraction of Mn and Co from manganese nodules from two different locations was studied in acid media and by reusing a steel slag obtained from a steel smelting process. An ANOVA analysis was performed to determine the most appropriate Manganese Nodule/Fe (res) ratio and time to dissolve Co and Mn from the nodules. Effect of temperature on the process was evaluated, and then a residue analysis was carried out. Finally, it was discovered that the best results were obtained when working at 60 • C in a time of 15 min, obtaining extractions of approximately 98% Mn and 55% Co. Additionally, the formation of polluting elements was not observed, nor the precipitation of Mn and Co species in the studied residues.

Eubrachyurans, or ‘higher’ true crabs, are the most speciose group of decapod crustaceans and have a rich fossil record extending into the Early Cretaceous. However, most extant families are first found in the fossil record in the Palaeogene, and particularly in the Eocene. Unfortunately, fossils of many early eubrachyuran groups are often fragmentary, and only a few studies have combined extinct and extant taxa in a phylogenetic context using different optimality criteria. Here, we report the dairoidid crab Phrynolambrus sagittalis sp. nov., an enigmatic eubrachyuran from the upper Eocene of Huesca (northern Spain), whose completeness and exquisite preservation permit examination of its anatomy in a phylogenetic context. Dairoidids have previously been considered among the oldest stone crabs (Eriphioidea) or elbow crabs (Parthenopoidea), two disparate and distantly related groups of true crabs living today. Mechanical preparation and computed tomography of the fossil material revealed several diagnostic features that allow a detailed comparison with families across the crab tree of life, and test hypotheses about its phylogenetic affinities. Phrynolambrus sagittalis is the first record of the genus in the Iberian Peninsula, and represents one of the oldest crown parthenopoidean crabs worldwide, expanding our knowledge of the biogeographical distribution of elbow crabs during the Palaeogene, as well as their early origins, anatomical diversity and systematic affinities. Understanding the disparity of Eocene eubrachyurans is pivotal to disentangling the systematic relationships among crown families, and interpreting the spatio-temporal patterns leading to the evolution of modern faunas.

New geochronological (U-Pb ID‑TIMS), geochemical and isotopic data from Upper Ordovician felsic volcanic rocks recorded in the Pyrenees and Mouthoumet massifs, SW Europe, suggest that this volcanic activity is more widely represented than previously accepted, and allows a better refinement of the age span involved in the Sardic unconformity. This Sandbian volcanism represents the final pulse of the Sardic tectonothermal event, started with the Floian-Darriwilian emplacement of voluminous plutonic rocks and the contemporaneous erosion of the uplifted pre‒Upper Ordovician basement, and followed by the emplacement of a tholeiitic volcanism contemporaneous with extensional features and the opening of (half-)grabens finally sealed by Hirnantian glaciomarine deposits. The Sardic-related lithospheric extension may be linked to thermal doming originated by a superplume activity causing, in turn, an extensive crustal melting responsible for the onset of the felsic (calc-alkaline-dominated), Floian-Darriwilian intrusive and Sandbian extrusive magmatism encased along the northern margin of Gondwana. Supplementary material at https://doi.org/10.6084/m9.figshare.c.6670226

Solutans were among the most enigmatic pre-radial and asymmetric echinoderms. A new species Dehmicystis ariasi sp. nov. is described from the upper part of the Llagarinos Formation, lower Ludlow (Silurian) of Northwest Spain. This is the first solutan formally described from Iberia and the first from the Silurian worldwide. Dehmicystis was previously known based on a small number of poorly preserved specimens from the Emsian, Lower Devonian Hunsrück Slate of Germany. New observations based on the newly studied material suggest that Dehmicystis displayed a feeding appendage facing towards the substrate, and the periproct on the opposite face of the theca. Comparisons with other solutans and new data suggest that Dehmicystis was a detritus feeder that moved over the substrate capturing organic particles from the sediment with a single feeding arm.

Citation: Silva, P.G.; Roquero, E.; Pérez-López, R.; Bardají, T.; Santos Delgado, G.; Elez, J. Lichenometric Analysis Applied to Bedrock Fault Scarps: The Sencelles Fault and the 1851 CE Mallorca Earthquake (Balearic Islands, Spain). Appl. Sci. 2023, 13, 6739. https://www.mdpi.com/journal/applsci

Lower–Middle Ordovician brachiopods are well known from the Central Andean Basin of Argentina and Bolivia, but relatively little data comes from its northern prolongation in the Altiplano and the Eastern Cordillera of Peru. Here we present information about brachiopods collected from the San José Formation (Fm) from several sections located at the northeast of the Apurímac River valley in the surroundings of Kimbiri city in the Eastern Cordillera. From northwest to southeast the sections and their locations are: Libertad, in the mountain trail between this hamlet and the city of Pichari; Catarata and Nueva Alianza, in the mountain trail between Oroya and the last hamlet; and Kimbiri (K), in the trail parallel to the Kashiroveni stream north of the village of Kimbiri Alto. In these localities the San José Fm lies unconformably on Neoproterozoic rocks, reaching the maximum thickness of about 700 m. This shale-dominated formation comprises a biostratigraphically almost complete succession of the upper Tremadocian to lower Sandbian strata and contains graptolites, trilobites, brachiopods, molluscs, echinoderms and ostracods, as well as some conodonts and other microfossils. The upper part of the San José Fm is unconformably overlain by a thick sandy and diamictic succession, known as the Kimbiri Fm. About 30 fossiliferous levels have been found in the San José Fm in the Kimbiri section, nine of which contain identifiable brachiopod remains and most of them are precisely constrained by graptolites. The lowermost brachiopod-bearing fossiliferous bed (K-03) occurs about 115 m above the base of the section, being assigned to the Baltograptus minutus Graptolite Biozone (GB) (upper Floian, Fl3) and containing a single specimen of a small indeterminate orthid. Stratigraphically higher in the formation, the next two assemblages in the beds K-07 and K-11, containing also upper Floian graptolites, provided Paralenorthis immitatrix. This species was originally described from the San Lucas locality of the Bolivian Eastern Cordillera, from rocks tentatively correlated with the upper Floian–lower Darriwilian. It also occurs in the San José Fm in the Inambari River section located in the Peruvian Eastern Cordillera, ca. 250 km to the east of Kimbiri, in the interval corresponding to the upper Floian–Dapingian(?). Sandstones occurring about 40 m higher, in the fossiliferous bed K-12, yielded a slightly more diverse assemblage composed of Mollesella planidorsalis, P. immitatrix and an indeterminate orthoid. M. planidorsalis is characteristic of the Loma del Kilómetro Member of the Suri Fm in the central Famatina Range, correlated with the Floian to middle(?) Dapingian based on the occurrence of conodonts of the Prioniodus elegans, Oepikodus evae and Baltoniodus navis conodont biozones. Less than 10 m higher, the sandstones of the bed K-13 only yielded two poorly preserved unidentifiable specimens of Ahtiella. Slightly higher, in the bed K-15 just below the Holmograptus lentus or Didymograptus artus GB, a more diverse assemblage is dominated by a new species of Phragmorthis as well as by P. immitatrix; additionally it contains few specimens of Ahtiella zarelae and a new species of Dalmanella. A. zarelae was exclusively reported from the San José Fm at the Inambari River section. From this level upwards, the brachiopod assemblages become homogeneous in the Kimbiri section (but dominance changes) and co-occur with graptolites of the Didymograptus artus GB (middle Darriwilian, Dw2). For instance, in the bed K-16 a new species of Dalmanella becomes predominant. The bed K-17 yielded only P. immitatrix. The highest sampled bed with brachiopods (K-21) is dominated by A. zarelae and a new Phragmorthis species, P. immitatrix is still present and unidentifiable specimens of Christiania occur. This particular assemblage occurs about 30 m below shales of the Nemagraptus gracilis GB (lower Sandbian, Sa1). The brachiopod occurrences cited above improve the knowledge of the late Early Ordovician–early Middle Ordovician faunas of the Peruvian Eastern Cordillera and emphasize strong connections of this region with the Bolivian Eastern Cordillera and Argentinian Famatina Range during that epoch. Additionally, the occurrence of Phragmorthis suggests connections with several low-latitude terranes and palaeocontinents, such as the Mayo Terrane, Laurentia, Baltica, and South China.

This article presents Q-Facies, an open-source Python package for quantitative analysis of hydrochemical facies (HF). HF is widely used to interpret the chemical characteristics of groundwater. However, it is difficult to analyse its spatial or temporal variability due to its qualitative nature and the small number of classes. To avoid these limitations, Q-Facies performs the parametrization of HF based on the calculation of five statistical indices on the Piper diagram: Blau, Standard Distance, Area, Shape and Orientation indices. The latter two allow the identification of ongoing facies-modifying hydrochemical phenomena. The software relies on standard Python libraries, and is available as a GitHub repository.

Cenozoic extension in the Western Mediterranean has been related to the dynamics of back-arc domains. Although, in most of its orogenic belts extension propagated into the fore-arc nappe domains. Here we revisit the structure, metamorphism and radiometric ages of the Tunisian Tell, where HP/LT rocks (350 ºC at 0.8 GPa), were exhumed by the sequential activity of extensional detachments after heating and decompression (410-440 ºC at 0.6-0.3 GPa) in a plate convergent setting. Normal faults thinning the Tunisian Tell detached at two different crustal levels. The shallower one cuts down into the Atlas Mesozoic sequence, involving Tellian Triassic evaporites in the hanging-wall forming halokinetic structures in the Mejerda basin late Miocene. The deeper-detachment bounds metamorphic domes formed by marbles and metapsammites from the Atlas domain. Illite crystallinity on Triassic rocks shows epizonal to anchizonal values, at deep and intermediate structural depths of the Tell-Atlas nappe belt, respectively. New U-Pb 49.78 ± 1.28 Ma rutile ages from Tellian metabasites, together with existing phlogopite 23-17 Ma K-Ar ages in Atlas marbles from the footwall of the deepest detachment, indicate a polymetamorphic evolution. The Tell rocks underthrusted the Kabylian flysch in the early Eocene. Further, early Miocene shortening thrusted the metabasites over lower-grade sediments, producing HP/LT metamorphism and ductile stretching at the base of the Atlas belt. The exhumation of midcrustal roots of western Mediterranean nappe belts after tectonic shortening is a common feature related to tearing at the edges of the subduction systems and inboard delamination of their subcontinental lithospheric mantle.

The Columbrets Basin is the largest Mesozoic rift basin of the Valencia Trough in the Western Mediterranean. The analysis of a seismic‐reflection survey makes it possible to reconstruct the tectonic fabric underlying the sedimentary basin, including the structure of the top of the lower crust and the Moho. It is proposed that the ductile deformation of the mid‐lower crust was the main mechanism controlling the basin geometry, with the radial flow of mid‐lower crust coeval with the reactivation of two large‐offset SW‐dipping normal faults, inherited from the precursor Permian–Triassic rifting. Mid‐lower crustal necking occurred below the major depocenters, immediately before hyperextension. Our results provide new insight into the formation of circular‐shaped basins and the evolution of depth‐dependent extensional processes during rifting.

An 'oasis' signifies a refugium of safety, recovery, relaxation, fertility, and productivity in an inhospitable desert, a sweet spot in a barren landscape where life-giving water spills forth from the Earth. Remarkable mythological congruencies exist across dryland cultures worldwide where oases or 'arid-land springs' occur. In many places they also provide specialised habitats for a remarkable array of endemic organisms. To inform their management, and maintain their integrity, it is essential to understand the hydrogeology of aquifers and springs. Gravity-fed vs artesian aquifers; actively recharged vs fossil aquifers, and sources of geothermal activity are important concepts presented here. There are salient examples of the consequences for oases of sustainable and unsustainable groundwater extraction, and other examples of conservation management. Oases are archetypes for human consciousness, habitats that deserve protection and conservation, and a lingua franca for multicultural values and scientific exchange. We represent an international Fellowship of the Springs (FoS) to encompass and facilitate the stewardship of oases and aquifers through improved knowledge, outreach, and governance.