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In this work we establish reliable correlations between density and magnetic susceptibility in three paramagnetic granites from the Pyrenees. In total, 128 sites (310 density measurements and >2600 susceptibility ones) were studied in the Mont Louis-Andorra, Maladeta and Marimanha granitic plutons covering the main range of variability of magnetic susceptibility. Regressions were calculated for every granitic body and an integrated linear function was obtained for the entire dataset: \u03c1 (kgm3) = 2566 (kgm3) + 0.541\u03ba (10\u22126 S.I.) (R:0.97). This relationship is only valid in the paramagnetic domain, where iron is mostly fractioned in iron-bearing phyllosilicates and the occurrence of magnetite is negligible (or at least its contribution to the bulk susceptibility). This relationship, likely different in other bodies, allows for transforming magnetic susceptibility data into density data, helping to constrain gravity modelling when density data from rock samples are scarce. Given the large amount of AMS studies worldwide, together with the quickness and cost-effectiveness of susceptibility measurements with portable devices, this methodology allows for densifying and homogenizing the petrophysical data when modelling granite rock volumes based on both magnetic and gravimetric signals.

X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - Gasteiz, Para detallar la correlación entre las cuencas de Ainsa y de Jaca (antepaís eoceno surpirenaico) y profundizar en el conocimiento de los efectos del crecimiento anticlinal en la sedimentación, se han tomado nuevos datos en el sector del valle del Ara situado al oeste del anticlinal de Boltaña, en concreto: un mapa geológico (1:25000); columnas detalladas, cortes geológicos, un estudio bioestratigráfico y un perfil magnetoestratigráfico de la serie, cuya potencia alcanza los 3 km. El análisis resulta en la división del conjunto en tres unidades regresivas separadas por dos intervalos transgresivos de menor potencia. El conjunto evoluciona desde una situación inicial de talud carbonatado, más profundo hacia el N, a la de un sistema fluviodeltaico, progradante hacia el O, sobre el cual se desarrolla un sistema fluvial con contribuciones septentrionales. La correlación de estas tres unidades con la cuenca de Ainsa sugiere que el anticlinal de Boltaña actuó en la zona de afloramientos como un alto submarino flanqueado por taludes carbonatados durante la etapa inicial, luego como un alto marino somero, separando sedimentación terrígena en el este de sedimentación carbonatada al oeste, para evolucionar a una situación de alto emergido sujeto a erosión y cortado por los sistemas fluviales.

X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - Gasteiz, Las remagnetizaciones químicas regionales relacionadas con procesos de enterramiento y diagénesis son un proceso ampliamente extendido en cuñas orogénicas y cuencas sedimentarias. Este proceso conlleva la neoformación autigénica de minerales ferromagnéticos s.l. en relación con el aumento de temperatura asociado al enterramiento. Sin embargo, todavía no se conoce bien la cinética de estos procesos, debido en parte a que la mayoría de las remagnetizaciones de este tipo descritas en la literatura científica se produjeron durante supercrones magnéticos. Los materiales turbidíticos eocenos de la Cuenca de Jaca (Pirineos Occidentales) muestran una remagnetización química de doble polaridad, registrando varios crones a lo largo de la secuencia sedimentaria remagnetizada. Dentro del proyecto UKRIA4D (PID2019-104693GB-I00/CTA), se va a realizar un estudio multidisciplinar para relacionar temperatura de enterramiento, mineralogía magnética y edad de la remagnetización con la que evaluar de manera empírica las relaciones cinéticas entre los distintos factores.

X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - Gasteiz, Los niveles salinos depositados antes de la deformación, tanto en márgenes pasivos como en contextos orogénicos, producen una deformación diferencial en los niveles por encima y por debajo del despegue salino. La distribución de los despegues salinos controla el acortamiento diferencial y la formación de arcos orogénicos y el diapirismo puede generar minicuencas asociadas a rotaciones de ejes vertical durante su desarrollo. Nuestro estudio, con 65 estaciones paleomagnéticas, pretende deducir la cinemática de estructuras salinas mediante el estudio de una porción del Arco Vasco, en el margen norte de la Cuenca extensiva Vasco-Cantábrica, donde la cobertera de la sal está compartimentada por varias paredes salinas (diapiros de Bakio, Bermeo, Guernica y Mungia). Los resultados muestran rotaciones antihorarias predominantes y rotaciones horarias y antihorarias en flancos opuestos de los diapiros. Los test del pliegue revelan que algunas estaciones están remagnetizadas mientras otras muestran magnetizaciones ¿prefolding¿. Los experimentos de magnetismo de rocas en parte de las muestras estudiadas confirman estas observaciones. A pesar de que son necesarios más análisis para entender el origen y la distribución de las remagnetizaciones, es posible establecer un modelo cinemático preliminar de la deformación suprasal junto a los materiales despegados infrayacentes., This work has been supported by the project SALTCON- BELT-CGL2017-85532-P funded by Agencia Estatal de Investigación (AEI) and FEDER. Some of the authors are members of the consolidated research group of Geodynamics and Basin Analysis 2017SGR596 of the Generalitat de Catalunya.

La deformación Alpina en los Pirineos Centrales dio lugar a un cinturón de pliegues y láminas de cabalgamiento que involucran al basamento paleozoico y a la cobertera mesozoico-cenozoica, esta última despegada sobre las evaporitas del Triásico. La zona de estudio abarca la mitad meridional de la Zona Axial, desde el granito de la Maladeta al oeste hasta el granito de Andorra-Mont Louis al este, así como la parte más septentrional de la Zona Surpirenaica. Este trabajo tiene como objetivo analizar las variaciones laterales de la estructura del subsuelo de la zona de estudio, en base a la estructura ya establecida a partir de trabajos geológicos y geofísicos previos. Para ello se han elaborado seis cortes geológicos seriados partiendo de dichos trabajos, de cartografías geológicas previas e introduciendo datos propios; también se ha llevado a cabo la recopilación y homogenización de los datos gravimétricos existentes (base de datos SITOPO (proyecto TopoIberia) y base de datos del ICGC), y la adquisición de más de 1000 nuevos datos; finalmente se han realizado 231 medidas de densidad de todas las litologías que afloran en el área estudiada. Todo ello para elaborar los mapas de anomalías de Bouguer y anomalía gravimétrica residual de la zona, así como la modelización gravimétrica 2.5 D de los cortes geológicos realizados. Los mapas gravimétricos y los cortes seriados obtenidos permiten observar variaciones laterales relacionadas con (i) la existencia o no de rocas evaporíticas, (ii) variaciones de la geometría en profundidad de los cuerpos ígneos tardi-variscos y (iii) variaciones laterales en la geometría de las láminas de cabalgamiento alpinas que involucran al basamento, The Alpine deformation in the Central Pyrenees generated a fold-and-thrust belt involving Paleozoic basement and decou- pled Mesozoic-Cenozoic cover units detached on the main décollement level located in the Triassic evaporites. The study area comprises the southern sector of the Axial Zone from la Maladeta granite in the west to the Andorra-Mont Louis granite to the east as well as the northernmost part of the South Pyrenean Zone. The goal of this work is to analyse lateral varia- tions of subsurface structure of the study area, which was established based on previous geological and geophysical works. With this aim, six serial geological cross sections were built using available geological maps and previous published works together with new data. More than 1000 new gravity stations were acquired and harmonized together with available data from SITOPO database (TopoIberia project) and ICGC database as well as 231 new density measurements taken from all rock types outcropping in the study area. Integration of all this information allowed us to calculate the Bouguer and residual gravity anomaly maps and to carry out 2.5 D gravity modelling along the six cross sections. Both, maps and cross sections, show lateral variations related to (i) occurrence or absence of Triassic evaporites, (ii) different geometry at depth of the Late Variscan igneous bodies and (iii) geometric lateral changes of the alpine basement-involved thrust sheets

Magnetostratigraphy is the subdiscipline of stratigraphy that aims to divide the stratigraphic record into intervals of homogeneous magnetic polarity, named magnetozones. Each magnetozone corresponds to a period of Earth history, named geomagnetic chron (or chron), limited by two geomagnetic field reversals. Since field reversals are globally isochronous, magnetostratigraphic divisions are true chronostratigraphic (time) units. A correlation with the Geomagnetic Polarity Time Scale (GPTS) is achieved if the sequence of magnetozones finds a pattern match with a sequence of reversals in the GPTS. In achieving this, absolute ages of geomagnetic reversals can be assigned to every magnetozone boundary in a local stratigraphic section. Magnetostratigraphy has been used to correlate fragmentary records from disparate regions, in order to build, in association with biostratigraphy and geochronology, a comprehensive Geological Time Scale.

vEGU21: Gather Online | 19-30 April 2021, This work presents preliminary paleomagnetic results from the Cadí basin, one of the Pyrenean Late-Carboniferous-Permian basins. These basins are the consequence of a complex tectonic evolution. At the outset, they were controlled by an extensional or transtensional regime during the progressive dismantling of the Variscan chain that gradually changed to a strike-slip fault regime. Afterwards, during Pyrenean compression (Late Cretaceous to Cenozoic) most of these basins were inverted and transported southwards as a part of the basement units. All of them are characterized by a similar subsidence pattern interpreted as graben or half-graben continental troughs. In a close relationship with its genesis, during Late-Carboniferous-Permian times, several magmatic events took place. Because of that, fluvio-lacustrine sediments present lateral changes to volcanic and volcanoclastic deposits and materials are sometimes cut by intrusions. The studied zone, the Cadí basin, is located at the eastern Pyrenees, south of the Axial Zone, and shows a high variability of Late-Carboniferous-Permian volcanic products in E-W continuous outcrops that reach several hundred meters of thickness with a good preservation and exposition. The Late Carboniferous-Permian evolution of the Cadí basin was strongly controlled by tectonics and volcanism. In order to characterize this stage and its volcanic rocks, we applied in a previous work the anisotropy of magnetic susceptibility (AMS) technique to determine the primary magnetic fabric of lava flows and volcanoclastic materials. A dominant WNW-ESE direction of the magnetic lineation was recognized related to the paleoflow direction. Paramagnetic minerals and magnetite were recognized as the main carriers of the AMS. In this work we present the paleomagnetic results from 15 sites (about 150 specimens) in volcanic, volcanoclastic and intrusive materials sampled along four N-S cross sections. The obtained results indicate that the carrier of the magnetization are both magnetite and haematite. The thermal demagnetization of samples shows a paleomagnetic component with unblocking temperatures from 480ºC with reversed polarity and very low inclination after bedding correction. In some sites a normal polarity component is also recognized. These results seem to be coherent with a magnetization coetaneous with the emission and deposition of these materials during Permian times. In cases where the samples record a normal component is important to take into account the complex structural situation of these outcrops.

vEGU21: Gather Online | 19-30 April 2021, Magnetostratigraphy is the key to put disparate chronological pieces together in a consistent chronostratigraphic framework. Provided that a long continuous record of reversals can be obtained from the sedimentary record, a correlation with the GPTS may be established. Magnetostratigraphy provides added value to the chronology as long as it keeps certain independence from external age constraints, such as bioevents calibrated elsewhere or radiochronologic data. An independent correlation is meant to not be anchored to a given chron on the basis of an external age constrain. Our experience recommends that external age constraints are best taken with flexibility, allowing for the searching of a best fit between the magnetic polarity sequence (in meters) and the GPTS (in million-years). This rationale relies on the fact that the Geological Time Scale is the tool that allows earth-scientist of many varied disciplines to understand and discuss about the dimension of time. But the time scale calibration is a task in continuous refinement. As the accuracy and precision of the dating tools increases, our ability to unravel lag times in geological processes increases too. As more refined data is produced, the calibration of the time scale reveals as an ongoing task rather than a final product. Here we present the case of the Eocene-Oligocene Transition (EOT) as recorded in alluvial-lacustrine sediments of the eastern Ebro Basin. An earlier work provided a magnetostratigraphic correlation that was in agreement with small-mammals biostratigraphic data. A key constraint to this study was the Santpedor locality, which yielded a characteristic post-Grand Coupure small mammal assemblage, then attributed to the lowest Oligocene. An extended record of the magnetostratigraphy has challenged the earlier correlation and puts forward an alternate scenario that reveals a misfit with earlier and recent biochronological interpretations of the fossil mammal record. The significance of this discrepancy in terms of heterochrony of biostratigraphic events, the punctuated character of faunal replacement across the EOT, and time lags between the marine and continental realms may need to be addressed.

X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - Gasteiz, Recientes estudios magnetoestratigráficos de alta resolución (secciones de Yebra de Basa, Olsón y Planiello-Aguilar), junto con otros registros previamente publicados, han permitido realizar un estudio detallado de las tasas de sedimentación (SR) a lo largo de la cuenca de antepaís surpirenaica. En este análisis se han reconocido tres tipos principales de depocentro: (a) un depocentro regional asociado a la flexión de la placa en la depozona de foredeep; (b) depocentros locales relacionados con el crecimiento de estructuras tectónicas en la depozona de wedge-top; y (c) un depocentro móvil, relacionado con la construcción de plataformas siliciclásticas, con diferentes situaciones asociadas con apilamientos progradacionales o retrogradacionales y episodios de estabilidad e inestabilidad en los taludes. Nuestro estudio evidencia la ausencia de una correlación directa entre los valores de SR y la subdivisión clásica de las cuencas de antepaís en depozonas. Así, la progradación de plataformas siliciclásticas, en ocasiones, tiene un impacto en las SR mayor que la pertenencia a una depozona estructural específica. El crecimiento de estructuras tectónicas en la depozona de wedge-top y el apilamiento de unidades en el hinterland puede dar lugar a escenarios de SR más complejos de lo esperado

X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - Gasteiz, Los mantos de cabalgamiento de Bóixols, Montsec y Sierras Marginales constituyen la principal curvatura orogénica del frente surpirenaico central. La parte frontal de este saliente se caracteriza por unos antiformes con núcleo salino de orientación oblicua y despegados en los niveles evaporíticos sinorogénicos de la cuenca de antepaís del Ebro. Estas estructuras deforman los depósitos paleógenos de la cuenca de antepaís. Con la finalidad de explicar la evolución cinemática de estas estructuras y el papel de los niveles evaporíticos en la geometría del saliente, se llevó a cabo el estudio de las rotaciones de eje vertical (VAR) en el sector de Artesa de Segre-Cardona. Se muestrearon 80 estaciones de paleomagnetismo en los materiales detríticos del Eoceno superior-Oligoceno del sector. Su análisis muestra principalmente unas rotaciones antihorarias, relacionadas con el emplazamiento hacia el sur de los mantos de corrimiento surpirenaicos. Adicionalmente, el estudio magnetoestratigráfico de las series del Eoceno superior-Oligoceno permite acotar la edad de las rotaciones observadas., The Bóixols, Montsec and Sierras Marginales thrust sheets make up the principal orogenic curvature of the central South Pyrenean front. The frontal part of this thrust salient is characterized by a series of oblique salt-cored antiforms, which are detached above the synorogenic evaporitic layers of the Ebro forealnd basin. These structures deform the Paleogene deposits of the foreland basin. A study of vertical-axis rotations (VAR) was carried in the Artesa de Segre-Cardona area, aiming to explain the evolution of the kinematics of these structures and the role of the evaporitic detachment levels in the geometry of the salient. 80 paleomagnetic sites were sampled on the Eocene-Oligocene detritic levels in the area. Their analysis shows predominant anti-clockwise rotations, related to the southwards emplacement of the South-Pyrenean thrust sheets. Additionally, a magnetostratigraphic study of the upper Eocene-Oligocene succession add constraints to the age of the observed VAR.

vEGU21: Gather Online | 19–30 April 2021, The characterization of the basement architecture of the Pyrenean Axial Zone, backbone of the chain, is crucial to understand its geodynamic evolution and the interplay between tectonism and magmatism. In this work, a new gravity-constrained cross section was built along the Central Pyrenees, between two of the largest Pyrenean Late Variscan granitic complexes, La Maladeta and Andorra-Mont Louis granites, to infer the geometry at depth of the basement host rocks. This cross section is ca. 65 km long and extends from the Mesozoic Bóixols basin in the South to the Late Variscan Bassiès granite to the North, close to the northern end of the Axial Zone. It is based on available geological maps, previous published works and new geological field data; together with newly acquired gravimetric stations (1141), to improve the existent spatial resolution of the gravity data from the databases of the Spanish and Catalan Geological Surveys, and density values from 65 rock samples covering all different lithologies in the cross section. Thus, its geometry at depth is constrained by means of an integrated 2.5D gravity/structural/petrophysical modelling. The La Maladeta and Andorra-Mont Louis granites appear aligned in a WNW-ESE direction and both lie within the same Alpine basement unit, the Orri thrust sheet. They are separated about 40 km by the WNW-ESE-oriented Llavorsí syncline, formed by Devonian and Silurian rocks and limited to the north and south by south vergent thrusts. This syncline is located between two large Cambro-Ordovician anticlinorium structures, the La Pallaresa and Orri massifs to the north and south respectively, formed by a monotonous alternation of shales and sandstones with some intercalations of limestones and conglomerates affected by very low to medium grade of metamorphism. Most structures show southern vergence along the cross section, and its southern part is characterized by the occurrence of Triassic evaporites, a significant detachment level decoupling deformation between the Paleozoic basement and the Mesozoic-Cenozoic cover rocks. The observed residual anomaly along the cross section shows a relative maximum, coinciding with the southern edge of the Axial Zone (Nogueras Zone) and southern half of the Orri massif, followed to the north by a relative large minimum. This gravity minimum in the core of the Axial Zone coincides with the northern half of the Orri massif, the Llavorsí syncline and southern half of the La Pallaresa massif and must be related at depth with rocks of lower density with respect to rocks located to the North and South. Two possible solutions have been postulated to explain the presence of lower density rocks: (i) the presence of Triassic evaporites at depth as a continuation to the North of the Triassic evaporites outcropping in the Rialp window located to the South and/or (ii) the presence of buried granitic bodies equivalent to the adjacent La Maladeta and Andorra-Mont Louis granites.

X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - Gasteiz, Reciente estudios arqueomagnéticos han detectado una caída en la intensidad del campo en torno al 3000 BP (Shaar et al., 2016). Este fenómeno se ha observado en distintas partes del mundo, como en Israel, Europa, y Corea. El principal objetivo de este estudio es ampliar nuestro conocimiento acerca del comportamiento espacial y temporal de dicho evento en la región de Asia central durante el I milenio AEC. Para esto se ha utilizado el protocolo de paleointensidad de Thellier en el tratamiento de 141 fragmentos cerámicos procedentes del sur de Uzbekistán. Los experimentos de magnetismo de rocas indican que los principales portadores magnéticos de las muestras son la magnetita y la titanomagnetita. Los resultados obtenidos confirman una caída drástica de la intensidad entre el 400 y el 100 AEC en la zona de Asia central. Por último, se han comparado los valores del Momento Dipolar Virtual Axial (VADM) con el valor del momento dipolar obtenido a partir del modelo global SHA.DIF.14k (Pavon-Carrasco et al., 2014).

X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - Gasteiz, En este trabajo se analiza, desde un punto de vista bioestratigráfico, las faunas de macroforaminíferos del límite Luteciense- Bartoniense. La serie estratigráfica estudiada se localiza en el flanco oeste del anticlinal del Boltaña, en el margen sur del río Ara (Zona Surpirenaica, Cuenca de Jaca-Pamplona). En un intento por recalibrar las SBZ (Shallow Benthic Zones) con la escala tiempo de polaridad magnética (GPTS), la Zona Surpirenaica ha proporcionado series adecuadas para una recalibración fiable de las SBZ del Luteciense, en las Sierras Exteriores, y del Bartoniense-Priaboniense, en la cuenca Surpirenaica oriental. Sin embargo, la ausencia de una serie continua en facies someras con presencia de macroforaminíferos, a lo largo del límite Luteciense -Bartoniense, ha impedido hasta la fecha la recalibración de dicho límite (SBZ 16-17). La sección compuesta de Aguilar-Planiello ofrece un registro continuo a lo largo del límite Luteciense -Bartoniense en facies marinas someras. En la base de esta sección, el Luteciense superior (SBZ 16) se encuentra caracterizado por una asociación de Nummulites deshayesi y N. cf. dufrenoyi. A techo, una asociación compuesta por N. perforatus y N. puschi caracteriza el Bartoniense (SBZ 17). La obtención de biomarcadores típicos del Luteciense superior (SBZ 16) y del Bartoniense (SBZ 17) muestra el potencial de la sección compuesta de Aguilar-Planiello para la recalibración magnetoestratigráfica de este límite.

The Parc Natural de l’Alt Pirineu is located between the La Maladeta and Andorra- Mount Louis granites. The characterization of the Parc’s geology at depth can help to know the emplacement mechanism of these granites, their relationships with the plutonic and volcanic rocks outcropping to the North and South of the Parc, respectively, and if all these rocks belong to the same magmatic system. To achieve these objectives, in the frame of the present research project, we have compiled and homogenezed previous gravimetric and magnetic data, and acquired new geophysical data, in particular, gravity data. We have also constructed new geological cross-sections oriented NE-SW from previous and new acquired geological data and characterized the petrophysical properties of the geological units in order to obtain the density and magnetic susceptibility of all different rocks outcropping in the study area. The geological cross-sections together with the petrophysical data will be used in the 2,5 and 3D gravimetric modelling to improve our understanding of the subsurface geology of this part of the Central Pyrenees and of the Parc Natural de l’Alt Pirineu., El Parc Natural de l’Alt Pirineu se encuentra en la zona situada entre el granito de La Maladeta y el granito de Andorra-Mount Louis. Conocer y entender la geología del subsuelo del Parc nos ayudará a saber cómo se produjo el emplazamiento de ambos macizos graníticos, su relación con las rocas plutónicas y volcánicas que afloran en la parte norte y sur del Parc, respectivamente, y si forman parte de un mismo sistema magmático. Para alcanzar estos objetivos, se está realizando una recopilación y homogeneización de datos gravimétricos y magnéticos ya existentes, así como la adquisición de nuevos datos geofísicos, en particular de gravimetría. Además, partiendo de estudios geológicos previos y datos propios, se está llevando a cabo la realización de cortes geológicos de dirección NE-SO y el estudio petrofísico de las unidades geológicas para obtener los valores de densidad y susceptibilidad magnética de todos los tipos de rocas que afloran en el área de estudio. Los cortes geológicos junto con los datos de petrofísica se utilizarán en la modelización gravimétrica 2,5D y 3D para mejorar la interpretación de la geología del subsuelo en este sector de II Jornades de Recerca del Parc Natural de l‘Alt Pirineu 87 los Pirineos Centrales y del Parc Natural de l’Alt Pirineu., Este trabajo se está llevando a cabo en el marco de los subproyectos CGL2017-84901-C2-1 y CGL2017-84901-C2-2-P del Ministerio de Ciencia, Innovación y Universidades. Los desarrollos metodológicos en exploración con técnicas geofísicas se encuentran alineados con el proyecto europeo 3DGeoEU- GeoERA (ERANET Cofund action 731166 [H2020], Project code GeoE.171.005). Los autores agradecen al Parc Natural de l’Alt Pirineu las facilidades prestadas y la organización de las jornadas de investigación para mostrar los trabajos realizados.

Recent studies indicate the existence of rapid fluctuations of the geomagnetic field intensity over the last 3000 years. These features have been observed during the first millennium BCE in the Mediterranean area (from Western and Central Europe to the Near East), and in other regions as the Canary and the Azores Islands, China and Korea. Nevertheless, due to the difficulty to obtain precise secular variation intensity curves, the spatial and temporal extension of these events, and the potential link between the different regional events observed are still under discussion. In this study, we focus on the rapid intensity decrease that seems to take place in central Asia during the second half of the 1st millennium BCE. We present 51 new archeointensity from South Uzbekistan, obtained by Thellier-Thellier method, also, rock magnetism experiments have been conducted in order to identify the principal magnetic minerals responsible for the magnetization. The results of those experiments show that the maghemite and/or magnetite, in some cases with low titanium content, are the main magnetic carriers. New data together with 73 previous archaeointensity data, allow us to better defined geomagnetic field intensity changes in South Uzbekistan between 600 BCE and 600 CE. The results indicate a rapid drop out in intensity between 500 BCE and 200 BCE with a minimum of 37.2 µT around 200 BCE ¿ 50 CE. A comparison with different VADMs values available for different regions indicates that similar intensity trends are observed during this period at the continental scale. Finally, the results are compared with Axial Dipole Moment estimations derived from different global models, suggesting that this sharp continental decrease is controlled by non-dipolar sources.

EGU2020: Sharing Geoscience Online, 4-8 May 2020, Geophysical surveying (both gravity and magnetic) is of great help in 3D modeling of granitic bodies at depth. As in any potential-field geophysics study, petrophysical data (density [r], magnetic susceptibility [k] and remanence) are of key importance to reduce the uncertainty during the modeling of rock volumes. Several works have already demonstrated that ¿18O or [SiO2] display a negative correlation to density and to magnetic susceptibility. These relationships are particularly stable (and linear) in the so-called ¿non-magnetic¿ granites (susceptibilities falling within the paramagnetic range; between 0 and 500 10-6 S.I.) and usually coincident with calc-alcaline (CA) compositions (very common in Variscan domains). In this work we establish robust correlations between density and magnetic susceptibility at different scales in CA granites from the Pyrenees. Other plutons from Iberia were also considered (Veiga, Monesterio). The main goal is to use the available and densely sampled nets of anisotropy of magnetic susceptibility (AMS) data, performed during the 90¿s and early 2000¿s, together with new data acquired in the last few years, as an indirect measurement of density in order to carry out the 3D modelling of the gravimetric signal. We sampled some sections covering the main range of variability of magnetic susceptibility in the Mont Louis-Andorra, Maladeta and Marimanha granite bodies (Pyrenees), all three characterized by even and dense nets of AMS sites (more than 550 sites and 2500 AMS measurements). We performed new density and susceptibility measurements along two main cross-sections (Maladeta and Mont Louis-Andorra). In these outcrops, numerous measurements (usually more than 50) were taken in the field with portable susceptometers (SM20 and KT20 devices). Density data were derived from the Arquimedes principle applied on large hand samples cut in regular cubes weighting between 0.3 and 0.6 kg (whenever possible). These samples were subsampled and measured later on with a KLY-3 susceptibility bridge in the laboratory. Additionally, some density data were derived from the geometry and weighting of AMS samples. After the calibration of portable and laboratory susceptometers, density and magnetic susceptibility were plotted together. Regressions were derived for every granite body and they usually followed a linear function similar to: r = 2600 kg/m3 + (0.5 * k [10-6 S.I.]). As previously stated, this relationship is only valid in CA and paramagnetic granites, where iron is mostly fractioned in iron-bearing phyllosilicates and the occurrence of magnetite is negligible (or at least its contribution to the bulk susceptibility). These relationships allow transforming magnetic susceptibility data into density data helping in the 3D modelling of the gravimetric signal when density data from rock samples are scarce. Given the large amount of AMS studies worldwide, together with the quickness and cost-effectiveness of susceptibility measurements with portable devices, this methodology allows densifying and homogenizing the petrophysical data when modelling granite rock volumes based on both magnetic and gravimetric signal.

Burial diagenesis is one of the main mechanisms claimed for explaining pervasive remagnetizations in sedimentary basins and orogenic wedges worldwide. It involves authigenic formation (e.g. chemical remagnetization) of magnetic minerals in response to enhanced temperature conditions at deep basinal positions. Key questions about the kinetics of this process in natural cases remain unsolved because most of the best-documented cases occurred during long-lasting magnetic superchrons. The Western Pyrenees display a dual polarity record of a burial remagnetization affecting the deepest part of the Eocene Jaca turbiditic basin and its underlying units. A preliminary study of 49 sites distributed along three cross sections reveals that postfolding (remagnetized) ChRM directions are found within the lowermost part of the studied sedimentary pile, which is affected by cleavage, in such a way that ChRM unblocking temperatures increase as a function of depth. Noteworthy, this remagnetization is associated with hysteresis data typical for chemical remagnetizations (samples falling mainly within the SP+SD+MD mixing line in the Day plot), and displays up to five different polarity zones that are consistent along strike in the three studied cross sections. Prefolding ChRM directions are found, in contrast, in the overlying sequence above the cleavage domain. We intend to carry out a detailed, multidisciplinary study of this remagnetization in the framework of the recently funded UKRIA4D project, that will integrate: A) a full characterization of the remagnetization front combining paleomagnetic and rock-magnetic data; B) characterization of the burial conditions based on SEM and TEM observations of mineral assemblages and temperature estimates from RAMAN spectroscopy on carbonaceous material; and C) magneto-biostratigraphic dating of the 7 km-thick overlying sedimentary sequence. Integration of these data will allow establishment of the burial conditions that led to the observed remagnetization, on which, at least, a qualitative kinetic model for burial remagnetizations will be developed.

Solid chronostratigraphy of drivers and strata is a fundamental condition behind our ability to decipher climate signals from stratigraphy. The Eocene Escanilla fluvial system, South Central Pyrenees, provides a unique opportunity to study an entire fluvial system from source to sink during times of active mountain building in the Pyrenees. New magnetostratigraphy (Lascuarre location) allows a high-resolution correlation through proximal, central and distal sections, which combined with carbon and oxygen stable isotopes data, provides a robust high-resolution temporal and climatic framework for the middle-Eocene South Pyrenean sediment routing system. This allows us to correlate a significant basin progradation event to the base of chron C18n.2n, which appears to coincide with a remarkable excursion of the stable isotopes corresponding to the MECO (Middle Eocene Climate Optimum). Moreover, spectral analyses on facies indices as proxies of environmental changes indicate that orbital eccentricity (400-kyr period) was a primary driver of stratigraphic evolution, superimposed to tectonics and not masked by autogenic processes. The higher power and amplitude of the peaks in the marine parts of the system could suggest that orbital signals are transmitted from downstream, linked to base level oscillations, and subsequently propagated upstream. We suggest that the main sedimentary excursion related with the MECO is favored by a coupled response to downstream and upstream perturbations. In particular, we propose that sea-level lowering combined with a relatively large increase of sediment discharge with respect to water discharge (Qs/Qw) promoted such an out-sized progradational event. As the MECO isotopic peak occurs at eccentricity minima, constant non-extreme seasonal contrasts endured, suggesting that the landscape response was led by factors other than abrupt seasonal contrasts that still contributed to enhanced physical weathering and a facilitated runoff.

34th IAS Meeting of Sedimentology (10-13 Sep 2019, Rome, Italy), The Belsué syncline crops out in an area of ca. 14 km2 in the southern margin of the Jaca basin (South-Central Pyrenees) which records the transition from marine to non-marine sedimentation over a period of 5.7 Myr during the Eocene (Bartonian-Priabonian). The studied strata are up to 900 m thick and represent a westwards-prograding delta complex, including prodelta (Margas de Arguis formation), delta front (Belsué-Atarés formation) and fluvial beds (Campodarbe formation). These strata were deposited in between two growing anticlines trending perpendicular to the direction of progradation: the Pico del Águila and Gabardiella anticlines. Throughout the syncline a number of transgressive-regressive cycles are governed by Milankovitch eccentricity cycles (Kodama et al., 2010; Garcés et al, 2014). In this work we aim at assessing the mechanisms driving sedimentary cycles by using forward stratigraphic modeling. To build the model we have used the DIONISOS OpenFlow (Granjeon & Joseph, 1999) to build a reference model of the Belsué syncline, on which different experiments using the available orbital solutions were tested. We explore the nature of changes in the sedimentary record in response to variations in eustacy, sediment supply, and water discharge. These parameters were modulated at different intensities, and tested independently and in different combinations using a Monte-Carlo approach. The results have been compared with the Belsué outcrops to find the best match with the transgressive-regressive cycles previously defined. In particular, our work is focused on the analysis of the geometry of the different delta front regressive units. In order to evaluate the solutions, a numerical comparison between a representative sedimentary log in the syncline and a virtual log at the same position in the model was carried out, and also a visual comparison of the outcropping section with the virtual equivalent section.

Reunión MAGIBER XI Portugal ,Condeixa a Nova (4 al 6 de septiembre de 2019), The geomagnetic field is a global feature with an important regional character. Its temporal and spatial variation can be observed from direct measurements such as satellites and logbook available since the 17th century. In order to know the behaviour of the geomagnetic field further in the past indirect measurements are needed. These indirect measurements (called paleo or archeomagnetic data) are based on the study of the remanent magnetization acquired by the iron oxides present in certain rocks and archaeological materials when heated at high temperatures (Néel, 1955)., This work was supported by two R&D&I projects, CERAC (HAR2016-75133-C3-1-P) led by V. Martínez and J.M. Gurt, and CONCERAC (HAR2016-75133-C3-3-P) led by E. Ariño, all funded by the Spanish Ministry of Science, Innovation and Universities. V. Martínez worked on this paper through the post-doctoral research contract Ramón y Cajal (RYC-2014-15789). M. Gómez-Paccard thanks to RYC-2013-14405. This congress was funded by Red de trabajo y laboratorios MAGIBERII (CGL2017-90632-REDT).

EGU General Assembly in Viena, Austria,7–12 April 2019, In northeast Iran, the suture zone of the Paleotethys is situated between the East Alborz Mountains to its south and the Kopet Dagh Mountains to its north. Both mountain belts represent large-scale oroclines, potentially resulting from the indentation of the quasi-rigid South Caspian Basin. The oroclinal shape of the Alborz Mountains has been associated with vertical-axis rotation based on paleomagnetic data. However, no evidence for rotation has been found in the northeastern Kopet Dagh. A plausible scenario is that most of the rotation in the Kopet Dagh has been absorbed along its western part. Here, we present results of vertical-axis rotation and anisotropy of the magnetic susceptibility (AMS) for sites located in the West Kopet Dagh. AMS data range from sedimentary to tectonic fabrics depending on the position with respect to local thrusts. Magnetic vectors do not show significant vertical-axis rotation, implying that no significant rotation took place since Cretaceous times in the western Kopet Dagh. A preliminary comparison of these results with previous data from East Kopet Dagh favours complex local folding kinematics for most of the Kopet Dagh rather than significant vertical-axis rotation.

Reunión MAGIBER XI Portugal Condeixa a Nova (4 al 6 de septiembre de 2019), In paleomagnetic research groups it is well known that commonly used plastic boxes, holders, glues, fixers, markers, etc. display magnetic properties to a certain extent. However, beyond very few works on inter-calibration of instruments (Sagnoti et al., 2003), the identification of potential noise sources (García et al., 2009) and a description of magnetic properties of very specific holders (Bossi et al., 2004), detailed information on the intensity, coercivity, magnetic carriers of most common sample holders is hard to find in the literature. A comprehensive characterization of these holder materials was never done so far., This work has been funded by a Project >Salvador Madariaga> (PRX17 /00462), by a TNA fellowship (EPOS-TNA-MSL-006/2017) and by the Applied Geology Group (GeoAP-E0117R) of the Government of Aragon. It has also benefited from the MAGIBER-II network (CGL2017-90632-REDT) funded by the Ministry of Science, Innovation and Universities.

AGU Fall Meeting 2019 in San Francisco, 9 – 13 December 2019, Recent archeomagnetic studies provide new evidences for rapid variations of the intensity of the geomagnetic field in the last millennia. In particular, during the first millennium BC, one of the biggest jerks of the geomagnetic field took place. This phenomenon has been observed in the Near East, Israel and Georgia, Germany and Western Europe. The main purpose of this work is to study the behaviour of the geomagnetic field intensity in Central Asia during the first millennium BC, a region and period of time for which very few high- quality paleointensity data are available. For this purpose, an archaeomagnetic study has been conducted over a collection of 68 ceramic fragments coming from three archaeological sites in the south of Uzbekistan: Kampyr Tepe, where samples from three different sites have been studied: the Citadel (-262 ± 113 BC), the ceramic workshop (-150 ± 50 BC) and the Lower City (-129 ± 41 BC); Kurganzol (-325 ± 75 BC); and Termez, where samples came from different stratigraphic units with ages between 350 BC and 350 AD. The Kurganzol collection has been dated by a variety of archaeological and historical constraints, while the Kampyr Tepe and Termez ceramics were dated by 8 different radiocarbon analyses. During the first stage of this work, rock magnetism experiments have been conducted on 43 samples in order to identify the principal magnetic minerals responsible for the remanent magnetization. The results show that magnetite and/or Ti-magnetite are the main magnetic carriers. In a second stage, we have conducted paleointensity experiments following the Thellier classical methodology, including the TRM and cooling rate corrections necessary to ensure the reliability of paleointensity estimations. The new results, together with prior high-quality data, confirm that the geomagnetic field underwent a steep dropout in intensity between 600 BC and 100 BC in Central Asia. Finally, the VADM values have been compared with the dipolar moment variation predicted by several global geomagnetic models. This comparison indicates that the VADM values are higher than global model estimations, which might indicate the strong influence of non-dipolar sources upon the rapid decrease observed.

Reunión MAGIBER XI Portugal ,Condeixa a Nova (4 al 6 de septiembre de 2019), A precise description of the evolution of the past geomagnetic field is important for the development of global and regional models, which can be applied to explain and predict the Earth’s magnetic field evolution and also can be used to archaeomagnetic dating. Few archaeomagnetic data before the third millenium BC are available in Europe, mainly due to the scarcity of appropriate archaeological remains for this time period. Recent archeomagnetic studies have demonstrated that burnt anthropogenic cave sediments related to stabling areas, also called fumiers in French archaeological terms, can provide a reliable record of the past geomagnetic field directions (Carrancho et al., 2009, 2013). The systematic archeomagnetic study of these materials combined with the available archaeomagnetic directions for this time interval, most of them derived from Eastern Europe, allowed the first European paleosecular variation curve for the Neolithic (Carrancho et al., 2013). Despite this improvement, more data, especially for Western Europe, are needed in order to better describe the evolution of the geomagnetic field in the past., The projects “Les Comunitats Prehistòriques del Massís de Garraf Nord. Fase 2. (CLT009/18/00034)”, “GEOMED (CGL2015-63888-R)” and the network ”MAGIBER-II (CGL2017-90632-REDT)” are acknowledged. Some of the authors are members of the consolidated research group 2017SGR596 of the Generalitat de Catalunya and the Geomodels Research Institute.

EGU General Assembly in Viena, Austria,7–12 April 2019, Glacial studies in mountain areas are hampered by the erosion of the sedimentary record, among other factors. However, in limestone areas, the traces of glacial advances and retreats can be recorded in karst cave deposits. This is the case of Picos de Europa mountains (N of Spain), which was covered by Pleistocene glaciers. In these mountains, previous studies established a local maximum at around 45 ka covering an extension of 180-190 km2, a subsequent general retreat after 37-39 ka, an advance associated with the Last Glacial Maximum, and the later disappearance after retreat. However, other advances and retreats during the Last Glacial Cycle remain practically unknown. Thus, we study the geomorphology of a karst cave named Hayéu del Osu (3.5 km length, 226 m depth) and its preserved palaeontological records to provide new data about the glacial evolution of Picos de Europa. The study cave has entrances located at 1250-1350 m altitude, 1 km south of the Covadonga Lakes, which represent a reference location for glacier research in the northern Iberian Peninsula. The geomorphological study of this cave reveals the presence of allochthon alluvial sediment that comes from the erosion of the upper part of the glacial valleys located to the S. The sediments were transported toward the N by fluvioglacial processes, finally entering into the cave. Five OSL ages allowed us to date two alluvial sedimentary sequences: 1) a first sequence deposited at 84-65 ka, and 2) a second sequence deposited 36 ka ago. Both sequences include fragments of dental enamel of Arvicolinae, an unusual evidence during MIS 4 in the NW Spain, especially in high areas. Moreover, bones of at least three individuals of chamois (Rupicapra pyrenaica) found in the cave were dated in 34-32 ka cal by AMS radiocarbon dating. All the fauna found in the study cave was not adapted to cold environments, as those covered by glaciers. These results provide data about glacial evolution in the area: 1) the glacier fronts were located at more than 1350 m altitude during 84-65 ka (mainly MIS 4); 2) according to previous research, a glacier advance took place at 45 ka with glacial fronts reaching up to 900 m asl; and 3) the retreat of the glaciers more than 3 km to the S from 45 to 32 ka, coevally with the second half of the MIS 3.

A forward sequence of folding is interpreted in the northwest Zagros fold belt using two new magnetostratigraphic studies to date non-marine foreland successions in the Afrineh and Chaman Goli growth synclines and integrating previous studies in the Lurestan and Fars arcs. The onset of growth is younger from the hinterland to the foreland and established at 13.5, 11.8, and 7.6 million years ago (Ma), spanning from Middle to Late Miocene, although the end of folding is in the Middle Pleistocene at about 1.5 Ma in the foreland front. In-sequence folding propagation toward the foreland occurred at a mean rate of 30 km/Myr with shortening rates of ¿1.9 mm/yr, using the onset of growth for Chaman Goli, Afrineh, and Changuleh well-dated synclines. The greater shortening of the Zagros continental collision occurred in its hinterland with continental overrriding of the Iranian block above the Arabian plate partially predating Neogene folding in the Zagros fold belt., The research was partially funded by projects and ALPIMED (PIE–CSIC–201530E082).

Foreland basins are characterized by the propagation of the deformation front towards the foredeep. This is typically accompanied by the incorporation of foredeep portions to wedge-top depozones leading to piggy-back basins. The transition from foredeep to wedge-top is usually related to a reduction of the sedimentation rates (SR). The specific objective of this study is to investigate the evolution in time and space of the SR along the Tremp-Jaca basin (TJB) by integrating the published data with strategically selected new logs and relate them with the local subsidence. At Eocene the TJB was divided in two connected sub-basins, the proximal thrust-top Tremp-Graus basin and the distal foredeep Ainsa-Jaca-Pamplona basin. A dynamic tectonic setting modified the subsidence distribution, and conditioned the sediment routing system. With the objective of approaching subsidence and the sediment routing system, a comparison of SR was made from the study of 12 logs representative of different positions in the basin, all accompanied with sufficient chronostratigraphic information, particularly magnetostratigraphy data. Ten of these logs (total thickness of ... m) were taken from literature; the other two were measured for the purpose, adding 2325 m of section completed with magnetostratigraphy data. The logs were correlated into a panel and the basis to derive compaction-corrected sedimentation rates for each magnetozone. Three main types of depocenter were recognized: (a) regional tectonic dominated, associated to the foredeep depozone; (b) local tectonic dominated, related to thrusting, folding and salt tectonics on the wedge-top depozone; and (c) depositional dominated related to the underfilled to overfilled accommodation front advance, with different situations associated with transgressive or regressive events. Our results show an evolution of the SR values and their relation to the depozone migration coeval to the TJB evolution allowing us to distinguish two evolutionary stages of the TJB Eocene: The Lutetian stage with a very variable SR in a more compartmentalized basin (wedge-top, foredeep and forebuldge depozones) controlled by the Pyrenean tectonic structures, and the Bartonian-Priabonian stage, when the whole area had been incorporated into the wedge-top, with generalized reduction of the SR values in a more connected basin. However, SR distribution expected for the main depozones is not always stated since local variations related to the basin infill and tectonics of the wedge-top modify the general trends.

Reunión MAGIBER XI Portugal ,Condeixa a Nova (4 al 6 de septiembre de 2019), Los estudios arqueomagnéticos se han convertido en una herramienta imprescindible para caracterizar las variaciones del campo geomagnético de los últimos milenios. Los datos que proporcionan este tipo de estudios permiten obtener curvas locales de variación paleosecular para las tres componentes del campo geomagnético: declinación, inclinación y, más esporádicamente, la paleointensidad. Un ejemplo de dichas curvas son las recientemente publicadas por Molina-Cardín et al., (2018) para Iberia de los últimos 3000 años. Sin embargo, se requiere un continuo aporte de nuevos datos arqueomagnéticos para mejorar la resolución espacial y temporal de las bases de datos arqueomagnéticas globales para refinar este tipo de curvas. Los datos arqueomagnéticos permiten, además, obtener modelos geomagnéticos regionales o globales cada vez más robustos (Pavón-Carrasco et al. 2009, 2014; Campuzano et al., 2019). En este trabajo presentamos nuevos datos arqueomagnéticos que se han obtenido recientemente gracias al estudio de varias estructuras arqueológicas calentadas a alta temperatura, muestreadas en varios yacimientos del levante español correspondientes al periodo Ibérico pleno. En concreto se han obtenido nuevos datos direccionales (declinación e inclinación) y de paleointensidad en los yacimientos de Pontós y Ullastret (Girona), además de los de Nulles y Coll del Moro (Tarragona) y Vinaroz (Castellón) que permitirán mejorar la resolución de la curva para la segunda mitad del primer milenio antes de Cristo. A pesar de que este periodo está bastante bien caracterizado gracias a estudios anteriores, los nuevos datos, especialmente los de paleointensidad, contribuyen a una mejor definición de las variaciones locales respecto a regiones cercanas donde las curvas de variación secular están mejor definidas (Hervé et al., 2013a y b).

The Paleocene (66¿56 Ma) was a critical time interval for understanding the geological history in high palaeolatitudes after the end of Cretaceous event (recovery from mass extinction, palaeoclimate, global sea level changes, among others). The sedimentary succession from Seymour Island (Antarctic Peninsula) provides key reference material from this important phase of the early Cenozoic. A detailed age model is proposed for the López de Bertodano Formation (LBF), Sobral Formation (SF) and Cross Valley¿Wiman Formation (CVWF) based on a new magnetostratigraphic section which integrates previous dinoflagellate cyst biostratigraphy, Iridium anomaly (K-Pg boundary), U-Pb zircon dating (airfall tuff) and strontium isotope values from macrofossils. The new composite magnetostratigraphic section, which includes the Cretaceous¿Paleogene boundary, has been correlated to the GPTS from C29r up to C24r. The top of the LBF is confirmed as latest Maastrichtian to earliest Danian (~65.4 Ma) in age. The overlying SF is mostly Danian in age (~65.2¿ ~63 Ma) and CVWF is Selandian¿Thatenian (~61.3¿56.9 Ma). LBF, SF and CVWF are unconformity-bounded units (alloformations) that record the geological evolution of the James Ross Basin during a period of relative decreasing tectonism but coeval with volcanic activity. Unconformity based internal units have been recognized, dividing each formation into allomembers (LBF: Molluscan and Cenozoic; SF: A, B and C; CVWF: Díaz, Arañado, Bahía Pingüino). The new age model allows correlation of base-level changes with eustatic sea-level fluctuations. The bases of the SF and CVWF are correlated with the 65.3 and 61.5 Ma sea level lowstands., This work was supported by the Instituto Geológico y Minero de España (IGME) and Dirección General de Investigación (DGI) from Spain by the projects CTM2011-30241-C02-02 and CTM2014-60451-C2-2-P. The authors want to thank the Geomodels Research Institute and the Grup de Recerca de Geodinàmica i Anàlisi de Conques (Grant no. 2017SGR596, supported by AGAUR). We

Reunión MAGIBER XI Portugal Condeixa a Nova (4 al 6 de septiembre de 2019), Además de la conocida aplicación de propiedades magnéticas de cortezas y hojas de árboles como proxies ambientales y/o de contaminación en ambientes antrópicos (Kletetschka et al., 2003, Maher et al, 2013 y Vezzola et al., 2017 y referencias citadas), es sabido que los árboles en medios naturales poco alterados también contienen partículas ferromagnéticas (Krs et al, 1994). Estos autores aplicaron técnicas paleomagnéticas convencionales (demagnetizaciones TH y AF, curvas IRM, etc.) en troncos de árboles vivos y fósiles y demostraron la presencia de minerales de baja coercitividad, con temperaturas de desbloqueo normalmente (pero no sólo) intermedias (300°C) y registros arqueomagnéticos dudosos (y viscosos magnéticamente), pero sin aportar datos relevantes sobre el origen de las partículas ferromagnéticas en el interior de los árboles. Por otra parte, algún trabajo posterior (Kletetschka et al., 2007 y Kletetschka 2011) ha sugerido algunas propiedades magnéticas como proxies climáticos en árboles sanos, no afectados por eventos traumáticos, de gran longevidad (sequoias). A día de hoy, muchas preguntas sobre el origen de la magnetización, los mecanismos de bloqueo y su estabilidad siguen sin resolverse., Este trabajo ha sido financiado por un Proyecto “Salvador Madariaga” (PRX17 / 00462) y por el Grupo de Geología Aplicada (GeoAP-E0117R) del Gobierno de Aragón. También se ha beneficiado por la red de trabajo y laboratorios MAGIBER-II (CGL2017-90632-REDT) financiada por el Ministerio de Ciencia, Innovación y Universidades. La curiosidad de Clara P. y el descubrimiento fortuito en 2014 de una cicatriz de rayo en una corta de madera motivó este estudio. También agradecemos al Ministerio de Transición Ecológica y a la AEMET por proporcionar datos sobre incendios y rayos, respectivamente.

The northern border of today Iran roughly marks the location of the formerly closed Paleo-tethys suture zone. The closure of the Neo-tethys further to the south, stress dispersion towards the north, and tectonic reactivation along the Paleo-tethys suture lead to the formation of the Greater Caucasus, the Alborz, and the Kopet Dagh mountains during the Cenozoic. The large-scale structural evolution of these mountain belts has been strongly affected by the indentation of the South Caspian Basin, which mechanically acts as a rigid block. In particular, it has been proposed that the Kopet Dagh and the East Alborz had undergone oroclinal bending due to the South Caspian Basin rigid block indentation, resulting in anti-clockwise vertical-axis rotation in theWest, and clockwise verticalaxis rotation in the East Kopet Dagh, respectively. Whereas vertical-axis rotation measurements exist for the Alborz mountains, there is a lack of data from the Kopet Dagh. Here, we present paleomagnetic directions and magnetic fabric deduced from anisotropy of magnetic susceptibility (AMS) measurements from several sites around the Kalat syncline along the northern mountain front of the East Kopet Dagh. Preliminary results of vertical-axis rotations rather indicate complex multi-phase folding evolution than large-scale oroclinal bending

Understanding the origin of stratigraphic cycles preserved in sedimentary successions is one of the main goals of sequence stratigraphy. Cyclicities in sediments are controlled by local and regional tectonics, global sea level and eustatic variations themselves linked to climate and global tectonics, as well as sediment supply also related to tectonics and climate. The Ainsa foreland basin (southern central Pyrenees, Spain), is composed of very well preserved syn-tectonic deep marine deposits in which stratigraphic cycles are characterized by an alternance of hemipelagic intervals and sediment gravity flow (SGF) deposits. The origin of stratigraphic cyclicity in the Ainsa basin has been largely discussed, however the absence of accurate chronostratigraphic constraints on the sandy systems of the basin remains one of the main issues to tie these pulses of coarse sediments with external factors. In this work, two age models were developed based both on new magnetostratigraphic data and stable isotope stratigraphy. New carbone and oxygen isotope data for the upper Hecho group were compiled with existing isotope profile of the lower Hecho group to provide a complete record for the entire deepwater succession of the Ainsa basin. The first age model considers continuous depositions in the basin and places our magnetostratigraphic results in the light of existing paleomagnetic studies previously performed in the Ainsa basin (Bentham and Burbank, 1996 ; Mochales et al., 2012a). It provides new time lines for the basin in agreement with the age model currently accepted for the South Pyrenean foreland basin. In the second age model, we used stable isotope signal combined with published large foraminifer biostratigraphic constraints (Scotchman et al., 2014). The obtained stable isotope curves show significant similarities with global isotopic records, with in particular a negative oxygen excursion towards the top of the succession that could be attributed to the Mid-Eocene Climatic Optimum. This age model is thus controversial as it is in significant disagreement with previous age models developed in the area and implies several important hiatuses in the slope depositional environments of Ainsa turbiditic series. In this presentation, we will discuss the two ages models and their implications for mountain building processes in the Pyrenees. Finally, we will use them to compare the stratigraphic record of the basin with sea-level fluctuations and discuss the possible primary drivers of stratigraphic signals.

Improving geomagnetic field reconstructions clearly poses a high-priority challenge in Earth Sciences today. A better characterization of the variation of the geomagnetic field strength at centennial to millennial time scales is particularly crucial to disentangle the long-term evolution of the Earth´s dipole moment, a global characteristic of our planet. Here we present new high-quality archeointensities for Central Asia, a vast and rather poorly known region in terms of geomagnetic field intensity fluctuations. These new data are obtained from the study of 26 pottery fragments from Termez, a great urban and Buddhist religious center in ancient Bactria (south Uzbekistan) during the Kushan period. The samples have been collected in several sectors related to different stages of the occupation as demonstrated by 14C analysis: 1) two sectors in the alluvial plain (AC2 and AC1), dated to the Greco-Bactrian (from the 3rd to the 1st centuries BC) and the nomadic Yuezhi (≈1st century AD) periods respectively; 2) sector RC at the Tchingiz Tepe fortress, dated to the Kushan and Kushano-Sassanian periods (from the 2nd to the 4th centuries AD). The classical Thellier method including regular partial thermoremanent magnetization (pTRM) checks and TRM anisotropy and cooling rate corrections has been used for archeointensity determination. The new data obtained shed new light on the past fluctuation of geomagnetic field strength in Central Asia. In addition, a critical revision of archeointensity data from Central Asia is presented. Selected high-quality archeointensities are finally compared with regional and global geomagnetic field reconstructions.

Sesión Científica de la Sociedad Geológica de España (61º. 2016. Zaragoza), Se ha analizado la fábrica magnética de los materiales sedimentarios depositados en ambientes continentales (Fms Campodarbe y Uncastillo) en el borde septentrional de la cuenca de antepaís del Ebro en dos sectores (Luesia y Fuencalderas) separados 12 km siguiendo la dirección de capa. Los resultados indican que la fábrica magnética se adquirió en un momento cercano al depósito de los materiales en una cuenca de antepaís ya que la lineación magnética (eje máximo del elipsoide magnético) se dispone perpendicular a la dirección de acortamiento que forma el orógeno pirenaico (siguiendo la dirección de capa) y el eje mínimo del elipsoide magnético se dispone perpendicular a la estratificación (o formando una guirnalda incipiente con el eje intermedio del elipsoide magnético). En el sector oriental muestreado (Fuencalderas), se observa una desviación de la fábrica magnética respecto a la dirección de capa en la Fm. Campodarbe que podría estar relacionada con la actividad de la terminación lateral hacia el oeste del cabalgamiento de San Felices., Departamento de Ciencias de la Tierra, Universidad de Zaragoza, España, Departamento de Geología y Geoquímica, Universidad Autónoma de Madrid, España, Laboratori de Paleomagnetisme, Centres Científics i Tecnològics, Universitat de Barcelona, España, Laboratorio de Paleomagnetismo, Instituto de Ciencias de la Tierra Jaume Almera, España, Unidad de Zaragoza, Instituto Geológico y Minero de España, España, Departament d'Estratigrafia, Paleontologia i Geociències Marines, Universitat de Barcelona, España

The eastern Pyrenees, particularly the Cadi Range, displays the less density and quality of paleomagnetic data of the chain. This paper revisited one of the central sections (Pobla de Lillet) where we have resampled Permian, Maastrichtian and Paleocene rocks. Best results were attained in the Permian red sandstones and in the Cretaceous limestones. In the Permian, two components with paleomagnetic meaning were identified. The high temperature component (up to 670 ° C) is similar to that defined in pioneering works, it appears to be primary and does not show significant rotations. The intermediate temperature component (up to 500 ° C), not identified in previous works, seems to be a syntectonic remagnetization with Alpine age. The characterization of rotations and the extension of this remagnetization (as an additional source of kinematics information) should be addressed in Permian rocks in future works since the paleomagnetic signal of Cenozoic rocks is of lower quality., Trabajo financiado con los Proyectos Pmag3Drest- CGL2009-14214 y DR3AM- CGL2014-55118 del MINECO y del 3DR3- PI165/09 del Gobierno de Aragón.

El Pirineo Oriental y en concreto la Serra del Cadí es uno de los sectores de la cadena con menor densidad y calidad de datos paleomagnéticos. En este trabajo se ha revisitado una de las secciones centrales (Pobla de Lillet) donde se han remuestreado rocas del Pérmico, del Maaestrictiense y del Paleoceno. Las rocas de mayor calidad son las areniscas rojas pérmicas y las calizas cretácicas. En las primeras se han identificado dos componentes con valor paleomagnético. La de alta temperatura (hasta 670°C) es similar a la definida en trabajos pioneros, es primaria y no muestra rotaciones significativas. La componente intermedia (hasta 500°C), no identificada en trabajos previos, parece ser una remagnetización sintectónica con el plegamiento (o basculamiento) alpino. La caracterización de rotaciones y la extensión de esta remagnetización (como fuente adicional de información cinemática) debería ser abordada en las rocas pérmicas en trabajos futuros en detrimento de las rocas cenozoicas cuya señal paleomagnética es de inferior calidad., Unidad de Zaragoza, Instituto Geológico y Minero de España, España, Laboratorio de Paleomagnetismo, Consejo Superior de Investigaciones Científicas, España, Laboratorio de Paleomagnetismo, Universitat de Barcelona, España, Institut de Ciències de la Terra, Jaume Almera, España, Geomodels Research Institute, Departament d'Geodinàmica i Geofísica, Universitat de Barcelona, España, Unidad de Magnetometría, Universidad de Vigo, España, Area de Estratigrafía, Departamento de Ciencias de la Tierra, Universidad de Zaragoza, España

[EN] Flint from Montmaneu's Limestones Formation of Rupelian age (Oligocene) is being here characterized. The analysis of the compositional texture, mineralogy and geochemical features has revealed this flint is highly pure and of microcrystalline texture, with a significant content of moganite. This flint is product of an early diagenetic replacement of limestone from littoral lacustrine facies. This flint was exploited by human populations in a regional range, especially in the early stages of the Neolithic., [ES] Se caracteriza el sílex de la Formación calizas de Montmaneu, de edad Rupeliense (Oligoceno). El análisis textural, mineralógico y de sus rasgos geoquímicos indica que se trata de un sílex microcristalino, bastante puro, con una proporción significativa de moganita. Es producto del reemplazamiento diagenético temprano de calizas de facies lacustres litorales. Este sílex fue objeto de una explotación regional, especialmente en los primeros momentos del Neolítico., Este trabajo forma parte del proyecto de constitución de una litoteca de rocas silíceas del NE peninsular (LITOcat). Los estudios sobre la explotación prehistórica del sílex de Montmaneu se llevan a cabo en el marco del proyecto "Aprofitament prehistòric i històric del sílex a Catalunya: contextos extractius i de primera transformació". Ambos proyectos son financiados por el CSIC-IMF y el Departamento de Cultura de la Generalitat de Catalunya.

Trabajo presentado en IberCrono: Cronometrías Para la Historia de la Península Ibérica, celebrado en Barcelona (España) del 17 al 19 de octubre de 2016

14th Castle Meeting (Magiber VIII) , Évora ,31 agosto-6 de septiembre 2014, The Zagros Mountain Belt is the result of the closure of the Neo-Tethys Ocean during the convergence between the Arabian and the Eurasian plates. From NE to SW the belt is divided into five parallel structural domains (Figure 1): (1) the Urumieh-Dokhtar magmatic arc, (2) the Sanandaj–Sirjan metamorphic and magmatic zone, (3) the Imbricated Belt, (4) the Simply Folded Belt, and (5) the Mesopotamian- Persian Gulf foreland basin. The Simply Folded Belt and the Mesopotamian foreland basin are the most external domains of the Zagros orogen. The Mountain Front trace defines two salient (Lurestan arc and Fars arc) and two re-entrants (Kirkuk Embayment and Dezful Embayment). The beginning of compression in the Zagros Belt was loosely constrained until recent magnetostratigraphic works in the upper continental successions shed some light on the timing of deformation (Figure 1). Magnetostratigraphic dating of syntectonic sediments indicates that deformation reached the frontal part of the Lurestan arc around 7.5 Ma and was active until the Pliocene-Pleistocene boundary (Homke et al, 2004). A similar study suggested older ages, around 11 Ma, for initiation of folding in the inner part of the Zagros belt (Emami, 2008). To the southeast, in more internal areas of the Simply Folded Belt near the NE side of the Fars arc, magnetostratigraphic dating indicates that folding occurred at 14–15 Ma (Khadivi et al. 2010). In order to extend and refine the timing of deformation in the frontal Fars area, a new magnetostratigraphic section was sampled in the Dowlatabad growth syncline. 208 sites were drilled along a ~ 2200 m stratigraphic section at an average sampling resolution of 10 m/site. The ages obtained were combined with ages provided by 5 samples for 87Sr/86Sr isotopes, 20 samples for calcareous nannoplankton and 5 large samples for low temperature thermochronology. Integration of all these results provides an accurate timing for the evolution of folding, drainage distribution and geohistory of this region.

New archaeomagnetic results from three archaeological kilns recovered from one archaeological site in north-east Spain are reported. The abandonment of kilns BC1 and BC2 has been dated by archaeological evidence to between ad 0 and ad 50, whereas kiln BC3 was abandoned later, between ad 50 and ad 150. Mean archaeomagnetic directions and archaeointensities have been obtained from classical Thellier experiments. The new data are consistent with previous archaeomagnetic data for the Iberian Peninsula. They add to and improve the description of palaeosecular variation during Roman times in Iberia. © University of Oxford, 2012., Financial support for this research was provided by a CSIC JAE-Doc postdoctoral research contract (MGP), the Spanish Ministry of Science and Innovation (projects CGL2008-02203/BTE, CGL2010-15767/BTE and CGL2011-24790) and Banco Santander – Universidad Complutense de Madrid (Grupo de Investigación 910396).

Integration of structural, stratigraphic, and paleomagnetic data from the N-S trending structures of the Ainsa Oblique Zone reveals the kinematics of the major thrust salient in the central Pyrenees. These structures experienced clockwise vertical axis rotations that vary from 70° in the east (Mediano anticline) to 55°in the west (Boltaña anticline). Clockwise vertical axis rotations of 60° to 45° occurred from early Lutetian to late Bartonian when the folds and thrusts of the Ainsa Oblique Zone developed. This vertical axis rotation stage resulted from a difference of about 50 km in the amount of displacement on the Gavarnie thrust and an accompanying change in structural style at crustal scale from the central to the western Pyrenees, related to the NE-SW trending pinch out of Triassic evaporites at its basal detachment. A second rotation event of at least 10° took place since Priabonian, as a result of a greater displacement of the Serres Marginals thrust sheet with respect to the Gavarnie thrust sheet above the Upper Eocene-Oligocene salts. The deduced kinematics demonstrates that the orogenic curvature of the central Pyrenees is a progressive curvature resulting from divergent thrust transport direction. Layer parallel shortening mesostructures and kilometer-scale folds also developed by a progressive curvature related to divergent shortening directions during vertical axis rotation. Rotation space problems were solved by along-strike extension which triggered the formation of transverse extensional faults and diapirs at the outer arcs of structural bends. Key Points Progressive curvature, divergent thrust transport direction Along-strike differential shortening by the distribution of weak salt levels Along-strike extension and related diapirism ©2013. American Geophysical Union. All Rights Reserved., This work was funded by the project INTECTOSAL (CGL2010-21968-C02-01) and by the “Grup de Recerca de Geodinàmica i Anàlisi de Conques 2009SGR1198” Secretaria d’Universitat i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya. Josep Poblet acknowledges financial support by research projects: “Geociencias en Iberia: estudios integrados de topografía y evolución 4D [TOPO-IBERIA]” (CSD2006-041) and “Desarrollo de fracturas y venas asociadas al plegamiento [FRAVEPLE]” (CGL2011-23628) funded by Spanish Ministries.

Evolution of the Zagros-Makran Fold Belts, Darius Workshop, 2012, 14-15 May 2012

The Paleogene sedimentary record in the Pontils area (SE sector of the Ebro Basin) consists of a ~ 2000-m-thick sequence formed by the Mediona Fm, the Orpí Fm, the Pontils Gp, the Santa Maria Gp and the Sant Miquel de Montclar Conglomerates. The age of these materials is loosely constrained based on stratigraphic relationships with marine sediments and punctual mammal fossils and charophyte assemblages within the continental materials. In order to precise their chronology, a magnetostratigraphic section up to 1500-m-thick in the Pontils-Sant Miquel de Montclar area has been studied and correlated to the Global Polarity Time Scale. From this correlation the age of the Pontils Gp is established in Lutetian to middle Bartonian, the Collbàs Fm would be middle Bartonian and the overlying Sant Miquel Conglomerates would range from Bartonian to Priabonian. This new chronology has been integrated with recent magneto- and biostratigraphic studies in more northeasterly sectors of the SE margin of the Ebro Basin (Igualada and Montserrat areas). This new and continuous chronological framework is essential to unravel and quantify the rates of change in the Ebro Basin-Catalan Coastal Ranges system., This work is a contribution of the Geomodels Research Institute and the GGAC Group 2009 SGR 1198 of the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya . It was funded by the project COFORSED CGL2010-17479

Se ha realizado un estudio magnetoestratigráfíco del relleno paleógeno continental de la cuenca de Almazán, combinado con datos bioestratigráficos. La sección estudiada se sitúa próxima a la localidad de Mazaterón, a lo largo del flanco nororiental del monoclinal de Gómara. El estudio comprende los sedimentos aluviales de la formación Almazul (230 m), que representa junto a la subyacente formación El Hocino el inicio de la sedimentación de la cuenca en este sector, las calizas palustres y lacustres de la Fm. Mazaterón (170 m), y las lutitas, conglomerados y areniscas fluviales de la Fm. Gómara (2250 m). A partir de la correlación con la escala de tiempo de polaridad geomagnética global ha sido posible determinar la edad de las formaciones. Los resultados indican que, la formación Almazul está en el cron C20, que representa una edad Luteciense, la Fm. Mazaterón representa un lapso de tiempo que incluye el tránsito Luteciense-Bartoniense, mientras que la Fm. Gómara representaría el resto del Bartoniense, Priaboniense y la mayor parte del Oligoceno Inferior, por tanto incluyendo el limite Eoceno-Oligoceno. El techo de la sección quedaría cerca del límite Rupeliense-Chatiense (Oligoceno) dentro del cron C10. La correlación magnetoestratigráfica permite asignar a los yacimientos de Mazaterón y Miñana (niveles de referencia de mamíferos paleógenos MP15-16), situados en los tramos superiores de la Fm. Mazaterón, una edad Bartoniense basal., Este estudio se ha financiado por el proyecto COFORSED (CGL2010-17479) del MEC dentro del Grupo de Investigación: “Geodinàmica i Anàlisi de Conques” (2009GGR 1198) y del instituto GEOMODELS (UB).

El sector occidental de la Cuenca de Guadix (Cordillera Bética, España) alberga un gran número de importantes yacimientos paleontológicos de macromamíferos. Con objeto de relacionar espacio-temporalmente dichos yacimientos, se ha elaborado un esquema detallado de correlación estratigráfica, a partir de secciones levantadas tanto en la vertical de los yacimientos como en posiciones intermedias. En este trabajo se presenta una actualización de dicho esquema, al que se han sumado los datos de paleomagnetismo recientemente adquiridos para tres secciones en las que aparecen yacimientos con información biocronológica precisa. La correlación magnetoestratigráfica con la escala de tiempo de polaridad geomagnética ha permitido datar los yacimientos más importantes que aparecen en el sector, así como determinar la edad del límite que separa las dos unidades genéticas más modernas del relleno continental de la cuenca, y calcular las tasas de sedimentación para el centro y los márgenes de la cuenca en dicho sector. The western sector of the Guadix Basin (Betic Cordillera, Spain) hosts a great amount of important macromammal fossil sites. In order to provide these sites with a precise chronostratigraphic frame, a detailed litho-magnetostratigraphic study has been carried out, and an actualized correlation scheme is presented. Magnetostratigraphic data, obtained for three of the stratigraphic sections measured, the sections with the most accurate biochronological information, are added to this scheme. The magnetostratigraphic correlation with the geomagnetic polarity time scale has allowed us to date the most important fossil sites of the studied area. Additionally, this work has led us to determine the age of the boundary between the two most modern genetic units of the continental filling of the basin, and to calculate the sedimentation rates for the basin center and margins in this sector. Este trabajo se ha realizado con la financiación y el apoyo de los proyectos del IGME 2001016 y 2005009, el Proyecto General de Investigación de la Dirección General de Bienes Culturales de la Junta de Andalucía, el Proyecto CGL2005-06224/BTE y el Grupo de Investigación RNM 163 de la Junta de Andalucía.

This article is composed of three independent commentaries about the state of Integrated, Coordinated, Open, Networked (ICON) principles (Goldman et al., 2021, https://doi.org/10.1002/essoar.10508554.1) in the Geomagnetism, Paleomagnetism, and Electromagnetism (GPE) section and discussion on the opportunities and challenges of adopting them. Each commentary focuses on a different topic: Global collaboration, reproducibility, data sharing and infrastructure; Inclusive equitable, and accessible science: Involvement, challenges, and support of early career, BIPOC, women, LGBTQIA+, and/or disabled researchers; Community engagement, citizen science, education, and stakeholder involvement. Data sharing practices and open repository use still varies strongly between GPE communities. Some have a long tradition of data sharing; others are only starting it. Globally, GPE leadership is strongly dominated by white males and diversity may increase through the creation of Science Equality Commissions. Improved global stakeholder involvement can increase research impacts and help fight inequalities. In all investigated topics we see promising beginnings but also recognize obstacles that include a lack of funding, a lack of understanding of diversity, and prioritizing short-term gain over long-term benefit. Nonetheless, we are hopeful that our community will embrace ICON science

The integration of biostratigraphy, strontium isotope stratigraphy, and magnetostratigraphy allowed for the precise dating of the >3.0-km-thick marine to non-marine foreland sedimentary succession within the Dowlatabad growth syncline along the Frontal Fars arc in the Zagros Fold Belt that extends from eastern Turkey to southern Iran. This area was the missing link to complete the dating of syntectonic deposits in the Fars arc and quantify the migration of sedimentary belts as well as the propagation of folding across the entire Mesopotamian foreland basin. Both are essential for defining the interplay of basin evolution and sequence of folding. Deposition of the foreland marine marls in the Mishan Formation started at ca. 11.5 Ma. The transition to a non-marine basin infill occurred at 4.9 Ma by the progradation of thick fluvial deposits of the Aghajari Formation with a fast accumulation rate of 63 cm/k.y. The beginning of growth strata deposition and thus the onset of folding in the Dowlatabad syncline is dated at 4.65 Ma. The first appearance of carbonate conglomerates sourced from the Guri limestone at 2.8 Ma marked the progressive dismantling of the nearby growing anticlines. The tectonic deformation in the front of the Fars arc was active for at least 2.85 m.y. and ceased at 1.8 Ma before the deposition of the discordant and slightly folded Bakhtyari conglomerates characterized by a clast composition derived from the Zagros hinterland. The compilation of magnetostratigraphic ages reveals that both the migration of the Aghajari-Bakhtyari sedimentary belts and the propagation of the folding front was in-sequence toward the foreland at a rate close to 20 mm/yr in the Fars arc and 15 mm/yr in the Lurestan arc, in the last 20 m.y. These high rates of folding propagation are about one order of magnitude larger than age equivalent shortening rates (∼4 mm/yr in Fars arc and ∼2 mm/yr in Lurestan arc) and thus imply an efficient detachment level at the base of the deformed Arabian sedimentary cover. Numerical experiments on both the cover and basement sequences are designed to test the influence of inherited basement structures on the deformation propagation within the cover sequence, providing clues on the partly coeval in-sequence deformation of the Zagros Simply Folded Belt and the local out-of-sequence Mountain Frontal Fault system as illustrated by regional and local geology., This research was funded by the DARIUS Programme as well as the Group of Dynamics of the Lithosphere, Geosciences Barcelona (Geo3BcnConsejo Superior de Investigaciones Científicas (CSIC), Spain. We thank the Paleomagnetic Laboratory Universitat de Barcelona Scientific and Technological Centers-Geo3Bcn, CSIC where the paleomagnetic analyses were conducted, and also the Laboratorio de Geocronología y Geoquímica Isotópica of the Universidad Complutense de Madrid, Spain, where the Sr samples were processed. In addition, the study of calcareous nannofossils was supported by the Research Group of the Basque University System IT-930-16. We are also grateful to the National Iranian Oil Company for their support during fieldwork. We thank DARIUS Programme and its sponsors, and projects Alpimed (PIE-CSIC-201530E082) and Subtetis (PIE-CSIC-201830E039) for additional support.