http://hdl.handle.net/10366/138661 Tue, 14 Jul 2026 23:55:43 GMT 2026-07-14T23:55:43Z http://hdl.handle.net/10366/172049 [EN]The seismicity in the SE Iberian Peninsula is distributed parallel to the coast in a well-developed strike-slip fracture system known as the Eastern Betic Shear Zone (EBSZ). This work focuses on the characterization of the shallow subsurface structure of the Algezares-Casas Nuevas Fault, within the Carrascoy Fault System of the EBSZ. The Carrascoy Fault borders the Guadalentín Depression to the south, which is a densely populated area with extensive agricultural activity. Therefore, this fault system represents a seismic hazard with significant social and economic implications. We have constructed two velocity-depth models based on P-wave tomography and Multichannel Analysis of Surface Waves (MASW) acquired from seismic reflection data. The resulting velocity models have allowed us to interpret the first ~250m depth and have revealed: i) the thickness of the critical zone; ii) the geometry of the Algezares-Casas Nuevas Fault; iii) the depth of the Messinian/Tortonian contact and iv) the presence of blind thrusts and damage zones under the Guadalentín Depression. Our results have also helped us to estimate an apparent vertical slip rate of 0.66±0.06m/ky for the Algezares-Casas Nuevas Fault since 209.1±6.2ka. Our results provide a methodological and backflow protocol to study the shallow subsurface of active faults, complementing previous geological models based on paleoseismological trenches, and can be used to improve the seismic hazard assessment of tectonically active regions around the world. Thu, 08 Sep 2022 00:00:00 GMT http://hdl.handle.net/10366/172049 2022-09-08T00:00:00Z http://hdl.handle.net/10366/172048 [EN]Wide-angle seismic reflection/refraction (WA) surveys provide data that can be modeled to obtain lithospheric-scale P-wave velocity (VP) models. The interpretation of these datasets is often performed as a laborious and time-consuming trial-and-error procedure, in which the relevant model parameters (layer thickness and VP) are manually adjusted until the forward modeling matches the observed travel-times. In this work, we present a fully automatic iterative nonlinear approach to invert WA datasets based on the simulated annealing technique. We test our proposed approach with data from the MARCONI-3 WA profile (southern Bay of Biscay) and compare the outcome with an existing detailed interpretation, discussing the similarities between the two models and the agreement between our model and the observed travel-times. Fri, 26 Nov 2021 00:00:00 GMT http://hdl.handle.net/10366/172048 2021-11-26T00:00:00Z http://hdl.handle.net/10366/172047 [EN]The critical zone (CZ) represents the most-shallow subsurface, where the bio-, hydro-, and geospheres interact with anthropogenic activity. To characterize the thickness and lateral variations of the CZ, here we focus on the Eastern Betic Shear Zone (EBSZ), one of the most tectonically active regions in the Iberian Peninsula. Within the EBSZ, the Guadalentín Depression is a highly populated area with intensive agricultural activity, where the characterization of the CZ would provide valuable assets for land use management and seismic hazard assessments. To achieve this, we have conducted an interdisciplinary geophysical study along the eastern border of the Guadalentín Depression to characterize the CZ and the architecture of the shallow subsurface. The datasets used include Electrical Resistivity Tomography (ERT), first-arrival travel time seismic tomography, and multichannel analysis of surface waves (MASW). The geophysical datasets combined help to constrain the high-resolution structure of the subsurface and image active fault systems along four transects. The resulting geophysical models have allowed us to interpret the first ~150 m of the subsurface and has revealed: (i) the variable thickness of the CZ; (ii) the CZ relationship between the fault zone and topographic slope; and (iii) the differences in CZ thickness associated with the geological units. Our results provide a method for studying the shallow subsurface of active faults, complementing previous geological models based on paleo-seismological trenches, and can be used to improve the CZ assessment of tectonically active regions Sun, 27 Mar 2022 00:00:00 GMT http://hdl.handle.net/10366/172047 2022-03-27T00:00:00Z http://hdl.handle.net/10366/172046 [EN]The immense advances in computer power achieved in the last decades have had a significant impact in Earth science, providing valuable research outputs that allow the simulation of complex natural processes and systems, and generating improved forecasts. The development and implementation of innovative geoscientific software is currently evolving towards a sustainable and efficient development by integratingmodels of different aspects of the Earth system. This will set the foundation for a future digital twin of the Earth. The codification and update of this software require great effort from research groups and therefore, it needs to be preserved for its reuse by future generations of geoscientists. Here,we report onGeo-Soft-CoRe, a Geoscientific Software & Code Repository, hosted at the archive DIGITAL.CSIC. This is an open source, multidisciplinary and multiscale collection of software and code developed to analyze different aspects of the Earth system, encompassing tools to: 1) analyze climate variability; 2) assess hazards, and 3) characterize the structure and dynamics of the solid Earth. Due to the broad range of applications of these software packages, this collection is useful not only for basic research in Earth science, but also for applied research and educational purposes, reducing the gap between the geosciences and the society. By providing each software and code with a permanent identifier (DOI), we ensure its self-sustainability and accomplish the FAIR (Findable, Accessible, Interoperable and Reusable) principles. Therefore, we aim for a more transparent science, transferring knowledge in an easier way to the geoscience community, and encouraging an integrated use of computational infrastructure. Tue, 26 Apr 2022 00:00:00 GMT http://hdl.handle.net/10366/172046 2022-04-26T00:00:00Z http://hdl.handle.net/10366/172045 [EN]Tectonic inversion of continental passive margins, orogens formation and deformation transfer to build intraplate ranges are processes that shape plate boundaries, define topography, and delineate continent/ocean transitions. However, the crustal deformation mechanisms that govern these processes vary depending on the tectonic setting and on the overlap of successive tectonic phases. The central and NW Iberian Peninsula comprises from north to south: (i) the North Iberian Margin (NIM), a partly inverted passive margin with limited oceanic subduction, (ii) the Cantabrian Mountains (CM), formed in the northern boundary of the Iberian microplate, and (iii) the Spanish-Portuguese Central System (SPCS), an intraplate mountain range. With the aim of unraveling the crustal-scale structure and the deformation mechanisms in these areas, we present a 650-km long cross-section from the NIM to the south of the Madrid Cenozoic basin based on new wide-angle seismic reflection/refraction data and on the reinterpretation of P-wave velocity (Vp) models. The hyperbolic moveout seismic data revealed an asymmetry of the PmP phases (Moho reflections) at both sides of the SPCS and deep subvertical reflectors to the south of the SPCS, that we interpreted as the image of south-vergent crustal-scale faults. In contrast, in the CM the Vp models presented show the northwards subduction of the Iberian lower crust. Therefore, the deformation mechanisms that govern the current crustal architecture in the central and NW Iberian Peninsula are a crustal-coupled deformation with significant vertical displacement in the SPCS and a crustal-decoupled deformation with mainly horizontal displacement in the CM. Tue, 01 Apr 2025 00:00:00 GMT http://hdl.handle.net/10366/172045 2025-04-01T00:00:00Z http://hdl.handle.net/10366/172030 [EN]Intraplate ranges are topographic features that can occur far from plate boundaries, the expected position of orogens as described in the plate tectonics theory. To understand the lithospheric structure of intraplate ranges, we focused on the Spanish-Portuguese Central System (SPCS), the most outstanding topographic feature in the central Iberian Peninsula. The SPCS is an Alpine range that exhumes Precambrian-Paleozoic rocks and is located at >200 km from the northern border of the Iberian microplate. Here, we provide a P-wave velocity model based on wide-angle seismic reflection/refraction data of the central SPCS (Gredos sector). Our results show: (a) a layered lithosphere characterized by three major interfaces: Conrad, Mohorovicic, and Hales discontinuities, (b) an asymmetry of the crust-mantle boundary under the SPCS, (c) the extent of the Variscan batholith forming the main outcrops of Gredos, and (d) the thinning of the lower crust toward the south. This model suggests that the exhumation of the SPCS basement was driven by a south-vergent thick-skinned thrust system, developed in the southern part of the SPCS and that promoted crustal imbrication and a Mohorovicic discontinuity's offset under the SPCS. Thus, the deformation mechanisms of the crust seem to be controlled by the presence of the late- to post-Variscan granitoids that assimilated the Variscan mid-crustal detachment creating a new rheological boundary. This tectonic structure allowed the formation of Alpine crustal-scale thrust systems that eased coupled deformation of the upper and lower crust, leading to limited underthrusting of both crustal layers. Sat, 02 Jul 2022 00:00:00 GMT http://hdl.handle.net/10366/172030 2022-07-02T00:00:00Z http://hdl.handle.net/10366/171385 [EN]This study investigates two burial‐related remagnetizations in the Jaca–Pamplona foreland basin (Southern Pyrenees): one with dual polarity and a positive reversals test, and another with only reverse polarity. These components, labeled C3 and C4 based on their mean unblocking temperatures, were identified from a paleomagnetic analysis of 142 sites in Eocene turbidites of the Hecho Group. Component C3 shows unblocking temperatures of 250°C–350°C, systematic reverse polarity, and a predominantly post‐folding timing. Component C4 exhibits unblocking temperatures of 250°C–550°C, dual polarity and a mainly syn‐to postfolding acquisition. The spatial distribution of C4 polarity defines WNW–ESE bands parallel to structures and younging southward. The acquisition of C4 is interpreted as a chemical remagnetization triggered by progressive burial driven by combined sedimentary and tectonic loading that increased temperatures (up to ∼250°C in the deeper northern sectors, according to previous paleotemperature studies). This thermal evolution promoted authigenic, stable single‐domain magnetite growth, beginning during the Lutetian (chron C20) and probably ending in the Rupelian (chrons C11‐C10) as uplift and exhumation progressed. In contrast, the reverse polarity and post‐folding behavior of component C3 suggest a mixed origin involving both chemical remagnetization and a thermoviscous overprint during the long chron C12r (Rupelian), contemporaneous with the youngest reverse C4 band and preceding the final exhumation of the basin. These findings highlight the complex interplay among tectonics, sedimentation, and chemical remagnetization processes in the South Pyrenean foreland, providing new insight into the timing and kinetics of remagnetization in fold‐and‐thrust belts. Thu, 01 Jan 2026 00:00:00 GMT http://hdl.handle.net/10366/171385 2026-01-01T00:00:00Z http://hdl.handle.net/10366/171384 [EN]The anisotropy of the magnetic susceptibility (AMS) in mudrocks has been widely used to study orogenic belts due to their sensitivity to strain, while paleomagnetism remains the most effective method to quantify vertical axis rotations (VARs) resulting from the accommodation of along-strike variations in shortening. However, AMS can be also eventually used as a passive marker to detect VARs and the integration of both techniques offers a powerful approach to understand the tectonic evolution of fold-and-thrusts-belts. In this work, a combined AMS and paleomagnetic study along a stratigraphic section of continental rocks from the Campodarbe Formation in the Jaca-Pamplona Basin, southern Pyrenees, was carried out. This stratigraphic section (Martes section) records the tectonic evolution of this part of the basin from Priabonian to Rupelian times. The magnetic fabrics show the imprint of early stages of deformation, characterized by dominantly oblate ellipsoids and WNW-ESE horizontal magnetic lineations (axes of maximum magnetic susceptibility kmax), parallel to bedding and the main regional structures. In the lower part of the section, kmax axes trend around 290º, gradually rotating to 270º towards the top. The AMS is interpreted as locked under the imprint of the layer parallel shortening (LPS) associated to the activity of the basement thrusts in the northern Jaca-Pamplona Basin. On the other hand, paleomagnetic data indicate clockwise VARs of 6º to 12º in the lower part of the section, and a counterclockwise rotation of 7º to 14º in the upper part. These differential rotations could result from lateral changes in the Biniés basement thrust or the Jaca thrust system that were active during Oligocene times. Both techniques record a net rotation of ca. 25º between the lower and upper part of the section, which support the interpretation that early-locked AMS behaves as a passive marker and validates its use for detecting and quantifying VARs. Thu, 01 Jan 2026 00:00:00 GMT http://hdl.handle.net/10366/171384 2026-01-01T00:00:00Z http://hdl.handle.net/10366/169933 [EN]We present a new magnetobiostratigraphic study of the Izaga composite section (South Pyrenean foreland basin), performed to investigate the possibility of defining the Bartonian GSSP and to assess the yet unexplored sedimentary expression of the Middle Eocene Climate Optimum (MECO) in the deep palaeoenvironments of the basin. Our results indicate that the section spans from the uppermost part of Chron C19r to the uppermost part of C18n.2n, comprising calcareous nannofossil biozones CNE14 and CNE15. As found in most prospective sections studied previously, the occurrence of delayed magnetizations has prevented precise delineation of the marker of the Bartonian GSSP, the short lived Chron C19n, which reinforces the idea that an alternative biostratigraphic event might need to be chosen as the primary marker of the GSSP. In this regard, we propose the highest occurrence of Sphenolithus furcatolithoides B, whose persistent location close to the top of C19n has been corroborated at the Izaga composite section. If this datum accepted, the Izaga composite section can be regarded as one of the best prospective successions to host the Bartonian GSSP due to its expanded nature and superb outcrop conditions. Our results also reveal an increase in the input of reworked calcareous nannofossils and organic matter of continental origin concurring with a negative shift in the carbonate carbon and oxygen stable isotope record around the C19r/C18n.2n boundary, and hence demonstrate that the enhanced hydrological cycle induced by the MECO is manifested along a complete continental to deep marine transect along the South Pyrenean basin. Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/10366/169933 2025-01-01T00:00:00Z http://hdl.handle.net/10366/169931 [EN]Underground hydrogen storage (UHS) is emerging as a promising tool for managing surplus energy derived from renewable energy sources. Rock salt (halite) formations, particularly solution-mined salt caverns, offer a secure and efficient storage medium due to their low permeability, self-healing properties, and chemical stability. Laboratory experiments simulating reservoir-like conditions are essential for reducing uncertainties surrounding hydrogen–rock interactions prior to large-scale deployment. This study investigates the response of rock salt to hydrogen exposure under controlled conditions (10 MPa, 60 °C, 30 d) in an autoclave. Two samples from the Eocene Barbastro Formation (Southern Pyrenees), recovered from a deep borehole within a potential salt cavern-type storage site, were tested. The halite samples included impurities such as anhydrite, quartz, feldspars, dolomite, calcite, and phyllosilicates, allowing assessment of non-halite phase reactivity also. Results indicate no significant mineralogical changes after hydrogen exposure. Observed alterations were minor and limited to localised halite recrystallization, slight particle detachment, and occasional chloride precipitation. These findings suggest an overall mineralogical stability of the salt matrix and impurities under the tested conditions and scales. By improving our understanding of hydrogen–rock interactions in evaporitic settings, this study contributes to ongoing efforts to develop safe, science-based solutions for underground hydrogen storage in salt caverns. Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/10366/169931 2025-01-01T00:00:00Z http://hdl.handle.net/10366/169929 [EN]This special volume of Journal of Iberian Geology brings together a set of articles selected from the presentations given at the XIII MAGIBER congress, a meeting held at the Faculty of Sciences of the University of Porto from the 25th to the 28th of July 2023. The organization of the meeting was led by colleagues of this university and of the neighbouring Institute of Earth Sciences in close collaboration with the Paleomagnetic Commission of the Geological Society of Spain, and was dedicated to the general theme of “Magnetism in Iberia: Results and New Frontiers”. The meeting brought together more than 50 researchers and students from Portugal and Spain, allowing everyone who works in the field of paleo- and geomagnetism to share their results and research activities (Fig. 1). The laid-back atmosphere of the meeting favoured the strengthening of existing collaborations and the development of new partnerships between scientists of the two countries, reaffirming that Geosciences have no borders. The topics addressed during the meeting included the anisotropy of magnetic susceptibility, geomagnetism, rock and environmental magnetism, archaeomagnetism, paleomagnetism, magnetostratigraphy and magnetotectonics, in what is a clear presentation of the multidisciplinary character of the discipline and of the scientific community involved in the meeting. The congress included two days of oral and poster presentations, a hands-on workshop on the applications and limitations of remanent magnetization curves unmixing led by recognized experts R. Egli and E. Font, and a field trip to the Praia de Lavadores in Porto (see https://magiber2023.wixsite.com/xiii-magiber). The full book of abstracts (Sant´Ovaia et al., 2023) can be downloaded from the website of the Paleomagnetic Commission of the Geological Society of Spain (https://sociedadgeologica.org/magiber-xiii/). Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/10366/169929 2025-01-01T00:00:00Z http://hdl.handle.net/10366/169928 [EN]The detailed analysis of the fracture geometry in the Panticosa granitoid (Axial Zone, Pyrenees) highlights the key role of structural analysis studies in characterizing water flow within fractured aquifers. Several fracture sets (striking ENE–WSW, NW–SE and north–south) were identified through photogrammetry (with nearly 30 000 mapped fractures) and fieldwork. A hierarchical classification of the fracture systems was established based on their continuity along-strike. The most prominent set, comprising individual faults that extend over several kilometres and exhibiting normal displacements of 10–50 m, also coincides with the dominant ENE–WSW orientation observed across multiple scales. These large, continuous structures probably result from recent tectonic activity or gravitational collapse. A second-order system includes NE–SW and NW–SE fractures ranging from metres to hundreds of metres in length. The distribution of the third-order set is more scattered and links longer fractures. Additionally, a set of dykes (mostly west–east striking) displays discontinuity contacts with the granite. We interpret that the studied fault sets are responsible for the upflow of thermal water (c. 45°C at the sources) of the deep aquifer from depths of 2 km. The higher continuity and transmissivity of the recent ENE–WSW fault system (showing thicker fault zones) made them more relevant for conditioning water flow. Thu, 01 Jan 2026 00:00:00 GMT http://hdl.handle.net/10366/169928 2026-01-01T00:00:00Z http://hdl.handle.net/10366/169916 [EN]The North Pyrenean Zone results from the Late Cretaceous‐Cenozoic inversion of the Mesozoic rift system extending along the Iberia‐Europe plate boundary. The western part of this inverted rift (from the Tardets‐Mauléon basin in the West to the Bigorre basin in the East) is strongly decoupled from the basement along Upper Triassic evaporites and slightly, internally overprinted by orogenic processes. These conditions make the area an ideal candidate for the study of rift‐related structures and mineral fabrics registering the kinematics of the rifting process. This work focuses on the study of meso and micro‐scale rift inheritance through a combination of structural analysis, anisotropy of magnetic susceptibility (AMS) and mineral shape fabrics extracted from X‐Ray microtomography analysis. Previous AMS results (Mauléon basin) are integrated with data from 64 new AMS sites, acquired across both the Mesozoic, syn‐rift cover and the Paleozoic basement. In syn‐rift units, magnetic and mineral fabrics are in agreement and at a great extent inherited from syn‐ and post‐rift stages. The compressional overprint of the Late‐Cretaceous‐Cenozoic inversion is limited and localizes along the south‐western margin of the inverted basin. In the Paleozoic, a partial overprint of Mesozoic extension on AMS occurs in areas where rift‐related peak temperatures exceeded ∼350°C. Rift‐related mineral and magnetic lineations reveal a regional and constant through time NNW‐SSE to NE‐SW extension that attests this ample domain of the Pyrenean rift opened under a roughly orthogonal or slightly oblique rifting. Its easternmost part registered a partitioning between N‐S and NW‐SE extension directions, likely controlled by pre‐rift faulting. Thu, 29 May 2025 00:00:00 GMT http://hdl.handle.net/10366/169916 2025-05-29T00:00:00Z http://hdl.handle.net/10366/169537 [EN]The oxidation of pyrite involves a series of chemical reactions that, depending on climatic conditions, can give rise to different mineral phases and morphologies. When oxidation takes place in semi-arid climate, the development of efflorescent salts on the surface of mine tailings is characteristic. These salts are mainly composed of Fe, Al and Mg sulfates and may accumulate valuable metals liberated through the dissolution of tailing minerals. This research aims to describe the evolution of salt precipitation from the economic and environmental perspective. For this purpose, we sampled efflorescent salts formed during the summer season on the surface of a tailing impoundment located in the north of Chile. The materials underwent comprehensive characterization utilizing X-ray techniques and scanning electron microscopy. The findings reveal a fractional precipitation in the crystallized salts. In an advanced oxidation system, characterized by multiple seasons of crystallization, dissolution and oxidation, the dry season begins with the precipitation of sulfates from a highly acidic solution dominated by Fe3+. This solution results from the dissolution and oxidation of the previous season sulfates. This initial stage is characterized by the presence of jarosite and gypsum, which are subsequently replaced by ferricopiapite. Towards the progress of the dry season, copiapite becomes more magnesian and precipitates alongside coquimbite and alunogen. Finally, halotrichite and pickeringite begin to crystallize. Base metal cations such as Co, Cu, Mn, Ni and Zn are preferentially incorporated into halotrichite-pickeringite sulfates during the most advanced evaporation phase. Thu, 20 Jun 2024 00:00:00 GMT http://hdl.handle.net/10366/169537 2024-06-20T00:00:00Z http://hdl.handle.net/10366/168666 [EN]Calcium carbonate (CaCO3) polymorphs are some of the most abundant minerals in natural environments on Earth’s surface. They are normally linked to fields including biomineralization, global CO2 exchange or pollutants remediation due to the strong surface interaction with heavy metals in the environment. The aim of this work is to study the crystallization of CaCO3 through precipitation experiments from aqueous solutions in the presence of different amounts of As(V), thus evaluating the capacity of the precipitating phases to remove As from solutions. Surprisingly, the results confirmed that the uptake mechanism operates relatively well, decreasing the initial concentration of arsenic in all the experiments conducted. On the other hand, the presence of this element controls the crystallization of calcite by inhibiting it, and stabilizing the less stable phase, vaterite, which under As-free conditions acts as a transient intermediate phase during the crystallisation process of amorphous calcium carbonate to the most stable polymorph, calcite. Different characterization techniques, including X-ray diffraction and ICP spectroscopy, were used to corroborate that the formation and stabilization of vaterite is linked to the presence of that pollutant. This phenomenon should be taken into account since natural CO2 sink, in the form of carbonate rocks, must be affected by the presence of this element, even at low concentrations, thus being the arsenic element even more poisoning than we thought until now. Wed, 24 Dec 2025 00:00:00 GMT http://hdl.handle.net/10366/168666 2025-12-24T00:00:00Z http://hdl.handle.net/10366/168480 [EN] We present a new structural study of a D2–M2 tectono-thermal structure in SW Iberia (Ponte de Sor–Seda gneiss dome) characterized by a spatial distribution of telescoping isograds providing a record of Buchan-type metamorphic conditions. The gneiss dome comprises an infrastructure made up of a lower gneiss unit (LGU) and an intermediate schist unit (ISU), separated by early D2 ductile extensional shear zones. The LGU and the ISU are composed of Ediacaran–Cambrian rocks that experienced the highest-grade M2 metamorphic conditions (amphibolite facies). Late Ediacaran–Early Terreneuvian and Late Miaolingian–Early Furongian protolith ages for LGU (496 ± 3 Ma) and ISU (539 ± 2 Ma) orthogneisses are reported. A superstructure made of Cambrian–Devonian rocks (Upper Slate Unit, USU) deformed under M2 greenschist facies conditions, tectonically overlies the ISU across a D2 extensional shear zone. Kinematic criteria associated with D2–M2 fabrics indicate top-to-ESE–SE sense of shear. A late-D2 brittle-ductile high-angle extensional shear zone (Seda shear zone) crosscuts the gneiss dome. D3 upright folds, thrusts and transpressive shear zones caused the steepening of D2 structures and the local crenulation of S2 foliation. The Mississippian D2–M2 event recorded in the Ossa–Morena Zone may be regarded as a regional-scale phenomenon that markedly influenced the crustal architecture of North Gondwana during the assembly of Pangaea. Sun, 01 Jan 2023 00:00:00 GMT http://hdl.handle.net/10366/168480 2023-01-01T00:00:00Z