Magnetoestratigrafía del Eoceno inferior y medio en el frente Surpirenaico (Sierras Exteriores): implicaciones cronoestratigráficas y cinemáticas

Esta tesis describe un trabajo centrado en la aplicaciones de técnicas paleomagnéticas con el fin de abordar diferentes problemáticas y enfoques estructurales en la parte central y oriental de las Sierras Exteriores de la Cuenca surpirenaica (del Pirineo Alto aragonés). Se presenta la adquisición un conjunto robusto y denso de nuevos datos magnetoestratigráficos a lo largo de casi 2 Km de serie en facies marino someras, principalmente de las Formaciones Boltaña y Guara con la finalidad de aportar una nueva cronología en la cuenca para el Cuisiense y Luteciense. Se presentan un conjunto significativo de datos bioestratigráficos para recalibrar de las biozonas de macroforaminíferos bentónicos involucradas. También se presenta un apartado de estudio de desarrollo metodológico de modelos numéricos y un caso de estudio que aborda en problema de solapamiento de componentes paleomagnéticas. Fuente de error que afecta los valores y estabilidad de los datos paleomagnéticos y que gracias a este estudio puede ser cuantificable y abordable. Finalmente, un estudio de generación de datos robustos y de calidad para el control de cinemática de la estructura del anticlinal de Balzes y alrededores del entorno de Arguis permite develar el origen mixto de la curvatura del pliegue y acotar etapas de plegamiento y rotación para las zonas de estudio. Estos aspectos en conjunto aquí desarrollados, aportan gran cantidad de datos de muy buena calidad y representan una aportación innovadora y significativa para el Eoceno inferior y medio de la Cuenca surpirenaica occidental

Flexural unfolding of complex geometries in fold and thrust belts using paleomagnetic vectors

Three-dimensional reconstructions of the subsurface are an important field in Earth Sciences due to their considerable socio-economic implications as exploration of petroleum resources. 3D reconstruction aims at providing a plausible image of the underground which entail the integration of discrete and heterogeneous datasets. They are based on geometric/mechanic laws and are designed to tackle areas with scarce and heterogeneous data. Restoration algorithms are an important tool to validate these 3D geological reconstructions of the subsurface. Restoration is the way back from the deformed to the undeformed states. Undo the deformation and achieve an initial surface with geological meaning is useful to validate the reconstruction of the folded structure and the deformation processes assumed. The main postulate in most restoration methods is the horizontality of the initial layers while restoration algorithms are based in several deformation processes as flexural slip or simple shear. We deepen in restoration techniques in next chapter but we want to emphasize the importance of a continuous feedback between reconstruction and restoration. This become especially important when complex deformation processes are implied and limited data is available. In addition, restoration tools may also be useful to predict deformation patterns for well characterized structures. However, existing restoration methods do not always succeed for complex structures like non-cylindrical, non-coaxial and/or areas undergoing vertical-axis rotations (out-of-plane motions). We suggest using paleomagnetic information, known in the undeformed (horizontal) and deformed states, as an additional and powerful constraint to improve restoration methods and to reduce the uncertainty of the results. The use of paleomagnetism in restoration tools was recommended in the early 1990¿s. So far, however, relatively few researchers have tried using paleomagnetic information to double-check the rotation inferred from restoration methods and hardly ever paleomagnetism is used as primary information of these tools. In this PhD we want to show how paleomagnetism can reduce the uncertainty in restoration tools when it is used as a constraint, particularly for structures with out-of-plane motions. The bedding plane is the basic 2D reference to relate the undeformed and deformed states, but never could be a real 3D indicator. Our proposal is the usage of paleomagnetism together with the bedding plane as references known in both states. The bedding plane determines the horizontal rotation and paleomagnetism the vertical axis rotation. Paleomagnetic vectors are the record of the ancient magnetic field at the time of the rock formation and we assume that it behaves as a passive marker during the deformation process. Its original orientation can be known in the undeformed surface, and it is represented by the paleomagnetic reference vector. If we see the deformation mechanisms, paleomagnetism allow reducing the number of variables, since it is a passive marker that records the internal deformation and provides us with information of vertical axis rotation. Because accurate paleomagnetic data is necessary to improve results we also work on a good data acquisition. Paleomagnetism may be incorporated in many restoration tools, particularly; we centre our study in geometrical surface unfolding algorithms valid for globally developable surfaces. Developable surfaces are those with Gaussian curvature equal to zero everywhere. These surfaces in geology are stratigraphic horizons folded under flexural conditions that have minimum internal deformation. That implies surfaces isometrically folded with preservation of lengths and angles and consequently with preservation of area. By globally we mean that these constraints are valid almost everywhere but there are areas where internal deformation is possible. We can find this kind of structures in the fold and thrust belts of competent layers at crustal levels. In order to test the restoration methods we develop analog models of complex structures. Laboratory-scale models are based on non-coaxial structures of External Sierras (Pyrenees). These analogs are digitalized with photogrametry and X-Ray CT scanner. In this way, models are completely characterized before and after deformation. This allows the calculus of real deformation of the folded surface and the comparison of the restored surface with the initial one

Sistema de Información Geográfica de las propiedades magnéticas de los granitos del Pirineo

En el presente trabajo se han georreferenciado las estaciones de medida de anisotropía de sus-ceptibilidad magnética pertenecientes a 21 cuerpos graníticos distribuidos a lo largo del Pirineo. Además se ha realizado una labor de homogeneización de la información que se ha plasmado en la generación de cartografías de síntesis, tanto a escala de cadena como de forma individual (ba-tolito), siguiendo los estándares de la Norma Cartográfica de Aragón. Estos datos provienen de distintas publicaciones sobre anisotropía de la susceptibilidad magnética (ASM) como técnica para caracterizar la estructura y deformación interna de los granitos, su modo de emplazamiento y su relación con la evolución estructural de las rocas encajantes

La Geología de las sierras de Santo Domingo y Salinas como recurso de desarrollo rural: Propuesta de guía divulgativa; propuesta de gestión y conservación

En este trabajo se valora la potencialidad de la geología de las Sierras de Santo Domingo y Salinas como recurso turístico que fomente el desarrollo rural del sector septentrional de la comarca de las Cinco Villas (Zaragoza). Para ello se propone la elaboración de una guía divulgativa y unas medidas de gestión y conservación del patrimonio geológico, enmarcadas en un futuro Plan de Ordenación de los Recursos Naturales (PORN). A partir de la síntesis geológica se resalta el valor excepcional de las Sierras y se seleccionan unos puntos de interés geológico y unos itinerarios que los enlazan. Síntesis geológica, inventario de puntos de interés e itinerarios son la base para la elaboración de la guía divulgativa. Con las medidas de gestión y conservación se contempla la puesta en valor del patrimonio geológico, sus usos y aprovechamiento (difundir el valor divulgativo, científico y turístico) y sus potenciales amenazas y pautas de protección. El ámbito rural es un buen soporte para dar a conocer y conservar el patrimonio geológico, y a su vez la geología puede representar un recurso adicional con el que contribuir a la reactivación económica del medio rural

Residual Bouguer anomalies in the Axial Zone (Central Pyrenees); characteristics and origin

Centro Nacional de Información Geográfica (España)[EN] This work integrates geological, geophysical and petrophysical data in order to study residual Bouguer anomalies localized in the Central Pyrenean Axial Zone (between the Noguera-Ribagorzana and Segre rivers to the West and East, respectively). The study area is characterized by thrust sheets of basement Paleozoic rocks forming an antiformal stack and southwards vergence due to the Alpine orogeny, high structural complexity related to the Variscan and Alpine deformation and scarce subsurface data. The Paleozoic rocks present a high variability both in lithology and age. The geological data are based on published geological cartographies and new acquired data, the gravimetric data consist of previous and new data acquired during the 2018 and 2019 (reaching a total of 3590 gravity stations) and the petrophysical data correspond to 526 density measurements. The Bouguer anomaly map of the study area shows a longwave relative minimum (~40 km) with several relative maxima and minima of short- and medium wave (between 2 and 20 km). The residual anomaly map, which allows to investigate the gravimetric anomalies that originated in the upper crust, shows a complex pattern of maxima and minima that does not follow the N110E Pyrenean main direction. Six NNESSO geological cross sections were gravimetrically modeled. The observed gravity response along the cross sections varies according to lithological and rheological changes in the upper crustal rocks, presence of evaporitic rocks both at surface and subsurface, presence of Upper Carboniferous granites, Ordovician gneisses and Neogene rocks belonging to the Cerdanya basin and rocks with different metamorphic grade. Our results also allow to delineate the lateral continuity of structures. This work highlights, in absence of other more resolute geophysical data, the high potential and applicability of gravity data acquired in structurally complex areas when combining with geological and petrophysical data in order to constrain geological models.Este trabajo se ha financiado con el proyecto PID2020-114273GB-C22 financiado por MCIN/AEI/10.13039/501100011033 del Ministerio de Ciencia e Innovación de España.Peer reviewe

Subsurface Geophysics and Geology (GEOFSU

[EN] The geophysics line at the IGME began in 1927 as a Geophysics Sectiondedicated to subsurface exploration. During all this time, it has been developed in order to support and give expert service in all IGME’s activities both as a geological service and public research institution, as well as a research and development work itself. On the other hand, in recent years the IGME has promoted a line of research aimed at the characterization and 3D modeling of geological structures and formations, the development of dedicated software and the evolution and sophistication of computer equipment. The new scenario of incorporation of the IGME to the CSIC as a national reference center in the field of Earth Sciences has allowed the establishment of the GEOFSUB Research Group (Subsurface Geophysics and Geology). It is constituted by 21 members who had been collaborating regularly of the IGME former scientific-technic areas Geophysics and remote sensing (Área de Geofísica y Teledetección) and Subsurface geology and 3D geological modelling (Área de Geología del Subsuelo y Modelización Geológica 3D). Our main differentiating element is our extensive knowledge of geophysical and geological techniques, which allows us to characterize the subsoil in an optimal waPeer reviewe

pilotSTRATEGY project 2021-2026: “CO2 Geological Pilots in Strategic Territories”

[EN] The pilotSTRATEGY (2021-2026) is investigating geological CO2 storage sites in industrial regions to support development of large-scale carbon capture and storage (CCS). It is focused on deep saline aquifers–porous rock formations filled with brine several kilometres below ground – which promise a large capacity for storing captured CO2. The goal of the characterisation is to assess the site’s containment, injectivity, capacity, integrity, hydrodynamics, and monitorability in order to ensure safe and permanent storage of CO2. PilotSTRATEGY covers the initial stages of project development up to the pre-final investment decision (pre-FID), regulatory approval and permitting of storage, and applied on selected structures of Paris Basin in France, the Lusitanian Basin in Portugal and the Ebro Basin in Spain, and in lower detail, in West Macedonia in Greece and Upper Silesia in Poland.The project has received funding from the European Union’s Horizon 2020 programme (10.1 million Euros, No. 101022664).Peer reviewe

A large-scale conical fold termination in the southwestern Pyrenees (Photograph of the month)

The limestone delineating the fold termination (known as San Marzal) belongs to the Guara Fm (Lutetian) and can be tracked in the two flanks of the Sto. Domingo anticline. The core of the anticline, apart from some minor remnants of the upper Cretaceous and Garum facies (≈ K/T), is made of Upper and Middle Triassic evaporites (Keuper and Muschelkalk facies) that are mostly covered by forest. The youngest materials are Bartonian and Priabonian in age (Arguis marls and Campodarbe Fms) and may together reach more than five kilometers in thickness. Focusing on the fold geometry, the two flanks of the Sto Domingo anticline are pseudo parallel and slightly verging to the South (right). The fold termination displays a strong plunge (≈ 65°) towards the West (towards us). Some minor geometrical disturbances are visible in the northern flank; a parasitic plunging fold (Peña Ronquillo), a minor back-thrust and small vertical faults cutting the northern part of the fold closure. The overall geometry of this fold is conical with an elliptical section and needs strong differential vertical axis rotations among the flanks to be developed, as has been demonstrated by paleomagnetic data. The San Marzal pericline is, in fact, the westernmost termination of the South Pyrenean sole thrust, a major discontinuity in northern Iberia that can be tracked more than 200 km up to this particular location. Position camera 42°28’ N and 000°58.166 W (ETRS89) at an altitude of about 1650 m (terrain altitude is about 1000 m)Unidad de Zaragoza, Instituto Geológico y Minero de España, Españ

Inventario de PIGs en el Paisaje Protegido de la Sierra de Santo Domingo (Prepirineo aragonés)

La Sierra de Santo Domingo se encuentra en el extremo occidental del prepirineo aragonés y ha sido recientemente declarada Paisaje Protegido (Decreto 52/2015, de 8 de abril de 2015, del Gobierno de Aragón). Desde el punto de vista geológico, representa el afloramiento del cabalgamiento basal en el Pirineo Occidental. La terminación occidental es un gran anticlinal (Santo Domingo) de despegue WNW-ESE que pliega estructuras Eocenas durante el Oligoceno-Mioceno. En este trabajo se ha realizado un inventario de 17 puntos de interés geológico (PIGs) y sus correspondientes fichas explicativas en dicha región. Con ello se pretende dotar de material divulgativo geológico de fácil acceso para el público, de manera que se fomenten las visitas a la Sierra con el objetivo de conocer sus diferentes aspectos geológicos, o lo que es llamado de otra manera: el geoturismo. Además, este inventario identifica los elementos geológicos susceptibles de ser protegidos bajo una serie de medidas de gestión y conservaciónUnidad de Zaragoza, Instituto Geológico y Minero de España, EspañaDepartamento de Física, Universidad de Burgos, EspañaDepartamento de Geografía y Ordenación del Territorio, Universidad de Zaragoza, Españ

Vertical axis rotations in fold and thrust belts: comparison of AMS and paleomagnetic data in the Western External Sierras (Southern Pyrenees)

Geometry and kinematics of fold-and-thrust belts can be complex settings when oblique structures and vertical-axis rotations (VAR) take place during thrust emplacement. Many techniques can be used to unravel such complex tectonic histories, from classic ones like strain analysis and changes of paleocurrents, to more modern approaches such as paleomagnetism and calcite twin analysis. In this paper, anisotropy of magnetic susceptibility is compared to vertical axis rotations deduced from paleomagnetic data along three cross-sections in the External Sierras and the Jaca Basin (southwestern Pyrenees). These data enable us to state that: 1) AMS represents pre-tilting deformation fabrics and magnetic lineation behaves like a passive marker during later deformation; and 2) a primary record of the paleomagnetic field can be found in the area. Therefore, the difference with the paleomagnetic reference is the local VAR. The comparison of the two datasets allows us to draw the following conclusions: A) the changes in both paleomagnetic VAR and magnetic lineation orientation between neighbouring sites are similar; and B) there is a significant linear regression between VAR and trend changes in magnetic lineation. Deviations in magnetic lineation with respect to the expected local magnetic lineation permit vertical axis rotations to be quantified using the AMS dataset. The combined analysis of paleomagnetic and AMS data enables: 1) a quicker comparison of the kinematic evolution in areas with similar AMS patterns; 2) the identification of anomalous orientations of magnetic lineation linked to VARs; and 3) the use of AMS analysis as a homogeneity test for VARs determined from other techniques. AMS is proposed as a suitable preliminary technique to select further sites for paleomagnetic analysis since paleomagnetic laboratory procedures are much more time-consuming than AMS measurements, AMS does not usually modify sample remanence and hence samples can be used for both types of analysis.Grupo GeoTransfer, Universidad de Zaragoza, EspañaUnidad de Zaragoza, Instituto Geológico y Minero de España, Españ