Evidence of remagnetized red-beds in the Middle Atlas (Morocco)

Se ha realizado un estudio paleomagnético en el límite entre el Atlas Medio Plegado y el Atlas Medio Tabular, en el entorno de los sinclinales de Skoura y Tighboula y el anticlinal de Boulemane. La finalidad de este trabajo es tratar de reconocer una remagnetización que afecte a los materiales sedimentarios de dicha área. Para ello se han realizado diferentes test de estabilidad: (i) dos test del pliegue, uno en el anticlinal de Boulemane muestreando cinco estaciones paleomagnéticas en calizas jurásicas, y otro en el sinclinal de Tighboula, con tres estaciones en capas rojas del Cretácico Inferior; (ii) un test del conglomerado en un nivel basal del Cretácico. Los resultados de dichos test indican que en capas rojas la componente característica es una remagnetización sinpliegue, mientras que la señal magnética en las calizas es débil y no permite aislar ninguna componente paleomagnética. La similitud en el comportamiento paleomagnético de las capas rojas (propiedades de la magnetización remanente natural, probable dirección NNW de la remagnetización, polaridad normal sistemática) con la observada en cuencas de similares características del Alto Atlas podrían indicar que ambas remagnetizaciones están relacionadas.A paleomagnetic study has been carried out in the boundary between the Folded Middle Atlas and the Tabular Middle Atlas, around Skoura and Tighboula synclines and Boulemane anticline. The goal of this work is to test the existence of a remagnetization affecting the sedimentary rocks in this area. For this purpose different stability tests were done: (i) two fold tests, one in the Boulemane anticline by studying five paleomagnetic sites located in Jurassic limestones, and the other in the Tighboula syncline in three sites from Cretaceous red-beds; (ii) a conglomerate test was done sampling a Cretaceous basal level and the overlying red-beds. The results of these tests show a synfolding remagnetization in the redbeds, whereas the magnetic signal of the limestones is too weak and it is not possible to isolate a magnetic component. Red-beds shows similar paleomagnetic properties than in other basins of the High Atlas (properties of the natural remanent magnetization, a probably NNW trend of the remagnetization and a systematic normal polarity), which could indicate a relationship between both.Proyecto CGL2012-38481 de la DGICyT, MINECO y por fondos FEDER de la Unión Europea

Capsaicin affects the structure and phase organization of phospholipid membranes

AbstractCapsaicin is a natural compound with pharmacological and toxicological effects, which given its hydrophobicity, can influence the structure of membranes. The interaction of capsaicin with model membranes of dipalmitoylphosphatidylcholine and dielaidoylphosphatidylethanolamine has been studied by using differential scanning calorimetry, fluorescent probe spectroscopy and 31P-nuclear magnetic resonance. Capsaicin remarkably affects the phase transition of dipalmitoylphosphatidylcholine, shifting the transition temperature to lower values, and giving rise, at relatively high capsaicin concentrations, to the appearance of two peaks in the thermogram. These peaks may correspond to separated phases as indicated by the partial phase diagram. Whereas capsaicin did not affect the fluorescence polarization of the probes diphenylhexatriene and trimethylammonium-diphenylhexatriene, it clearly affected that of the probe 2-anthroyloxystearic acid, indicating that the perturbation produced by capsaicin on the membrane would be mainly at the position where this fluorophore is located. On the other hand, capsaicin, at relatively low concentrations, gives rise to immiscible phases in the presence of dielaidoylphoshatidylethanolamine and decrease the temperature of the lamellar to hexagonal HII phase transition. At concentrations of capsaicin higher than 0.3 mol fraction, isotropic phases were detected. The possible implications of the effects of capsaicin on biological membranes are discussed

Magnetic extractions and electronic microscopy observations in Jurassic remagnetized carbonates

IX Congreso Geológico de España, Huelva, 12-14 de septiembre, 2016El estudio de la remagnetización en rocas carbonatadas viene realizándose durante los últimos 40 años, tanto por medio del análisis de sus propiedades magnéticas como tratando de realizar observaciones por medio de microscopía electrónica (SEM/TEM). Los resultados obtenidos con el primer análisis han proporcionado numerosos datos y hoy en día sabemos que generalmente la remagnetización es portada por magnetita. Ésta es de tamaño nanométrico generada durante la diagénesis, correspondiéndose con una remagnetización química. Sin embargo, los numerosos intentos de observación de dichos cristales por medio de SEM/TEM siempre han sido infructuosos y los cristales observados siempre presentan tamaños dentro del rango multidominio. En un nuevo intento de observación directa de dichos cristales mediante microscopía electrónica, hemos realizado nuevos ensayos sobre extractos magnéticos en calizas jurásicas remagnetizadas de las cuencas del Alto Atlas (Marruecos), Cameros y Vasco-Cantábrica (España) según las últimas técnicas propuestas en la literatura. Las propiedades magnéticas de los diferentes subproductos provenientes del proceso de extracción indican una pérdida de material magnético durante el mismo, principalmente las partículas de grano más fino (granos de tamaño monodominio y superparamagnético). Igualmente, mediante SEM/TEM únicamente han podido observarse cristales de magnetita multidominio.Since the last 40 years the analysis of remagnetized carbonates is under debate, by studying their magnetic properties and by using electronic microscopy (SEM/TEM). Results obtained from the first analyses allowed to infer that remagnetization is carried generally by nanometric magnetite and generated during the diagenesis, therefore it corresponds to a chemical remagnetization. However, several attempts to observe these magnetites by SEM/TEM were unsuccessful and in all cases the observed magnetite was in the range of multidomain size. In a new attempt to observe these crystals by electronic microscopy we did new magnetic extracts (according the last techniques proposed in the literature) in Jurassic remagnetized limestones of the High Atlas (Morocco), Cameros and Basque-Cantabrian (Spain) basins. Magnetic properties of the different sub-products of the extracts show a lost of magnetic material during the procedure, mostly of the smallest size (superparamagnetic and single-domain size). Likewise, only multi-domain magnetite grains were observed by SEM/TEM.proyecto CGL2012-38481 de la DGICyT, MINECO y fondos FEDER de la Unión Europea, así cómo por el programa de financiación de la NSF (EEUU) al Institute for Rock Magnetis

The carriers of AMS in remagnetized carbonates. Insights for remagnetization mechanism and basin evolution

Magnetic fabrics are usually studied to unravel the evolution of sedimentary basins, mainly focusing the attention in paramagnetic minerals. However, since basins are sometimes affected by burial-related chemical remagnetizations, magnetic fabrics can also be carried by authigenic ferromagnetic minerals related to remagnetization processes. Consequently, the study of the different types of fabrics can give complementary and valuable information about the evolution of sedimentary basins. Here, we explore, in the Jurassic carbonates of the Central High Atlas (Morocco), the role in magnetic fabrics of authigenic magnetite that grew during the Cretaceous (ca. 100 Ma) widespread remagnetization event. Magnetic fabrics are studied in 53 sites using the anisotropy of the magnetic susceptibility measured at room temperature (RT-AMS) and comparing results with sub-fabrics that alternatively enhance the paramagnetic and the ferromagnetic signal. Furthermore, an innovative analysis is proposed, comparing the magnetic fabrics before and after bedding correction (the common procedure) with fabric orientation after partial bedding correction. We use the paleomagnetic information to reconstruct the attitude of bedding at the remagnetization time and to restore the magnetic fabrics at this time. The performed analysis allows interpreting RT-AMS in terms of the contribution of different subfabrics, and the relationship between these, tectonic processes and the magnetic mineralogy. Four RT-AMS types are defined: T1 is carried by superparamagnetic magnetite that grew during the remagnetization stage and shows a horizontal lineation parallel to the extension direction at this time; T3 and T4 are carried by paramagnetic minerals and show compressive fabrics with the magnetic lineation parallel to intersection (bedding-cleavage) lineation; finally, T2 shows a mix between ferrimagnetic and paramagnetic fabrics.MINECO (Spanish Ministry of Economy and Competitiveness) cofinanced by the ERDF (European Union) (research projects CGL2012-38481 and CGL2016-77560)

Extensional vs. compressional deformation in the Central High Atlas salt province: a paleomagnetic approach

In this paper we address the problem of the distinction between diapiric, salt-driven and compressional structures, using the outstanding example of the Central High Atlas (Morocco). A remagnetized component carried by magnetite has been isolated in 32 new paleomagnetic sites. It is characterized by: maximum unblocking temperatures around 450 °C, syn-folding behavior and normal polarity. These 33 mean paleomagnetic directions were analyzed together with other 68 from published works around the study area to construct a robust paleomagnetic dataset along a cross-section perpendicular to the main structures. The remagnetization direction (n: 100, Dec: 332.2°, Inc: 34.5°, η: 6.2°, ξ: 2.0°, A/n: 6.427°) and the paleo-dip of beds (the attitude of the beds at the remagnetization occurrence) were calculated through small circle methods. The remagnetization can be dated as ca. 100 Ma. Because of its occurrence between the extensional and compressional periods, this remagnetization offers the possibility of restore the basin to its pre-inversion geometry. Comparison between present-day and pre-inversion structure allows discriminating three different evolutionary patterns: (i) thrusted and welded salt-walls mainly structured during the extensional stage (Ikkou ridge) with steep limbs close to the salt-wall core. (ii) Jurassic salt-walls with weaker deformation, restricted to the areas adjacent to the structure (Tadaghmamt and Timedouine); in this case, Cenozoic compression is limited to welding of the salt-walls and buttressing of the sedimentary sequences against faults. (iii) salt-rollers gently initiated during the Jurassic (Toumliline diapir), thrusted during the Cenozoic compression. Results show the importance of salt tectonics both during extension and compression, as well as the control of the compressional features by the inherited extensional structures. The performed restorations prove that paleomagnetism is a useful, independent tool to obtain palinspastic restorations and to separate, and quantify, the imprint generated during the basinal stage from the inversional features.MINECO (Spanish Ministry of Economy and Competitiveness) cofinanced by the ERDF (European Union) (research projects CGL2012-38481 and CGL2016-77560

Gravity and magnetic anomalies in the allochthonous Órdenes Complex (Variscan belt, northwest Spain): Assessing its internal structure and thickness

The Órdenes Complex is the largest Variscan allochthonous structure of NW Iberia, and preserves the suture of a long-standing Paleozoic ocean, probably the Rheic. Gravity and magnetic data, the latter specifically acquired on land for this study, show that the complex occupies the core of an open synform with a maximum depth of 9–10 km, which contrasts with the flat geometry of the lower crust and Moho discontinuity beneath. The maximum depth reached by the ophiolitic rocks marking the suture is around 7 km. The allochthonous units formed by basic and ultrabasic rocks are lens-shaped in section, and occur not only at the periphery of the complex, but form wide ribbons trending NE-SW to N-S. The Bouguer anomaly related with the longest of them, the Fornás Unit, previously used to support an autochthonous interpretation of the complexes, is modeled as a rootless, massive amphibolite body with a maximum thickness of 6 km located at the downthrown block of a large normal fault cutting across previous thrust faults and extensional detachments. The main magnetic anomalies are associated with ultrabasic rocks cropping out in the NW and SE, but a weak, wide anomaly in the central part of the complex is related with one or more thin layers of amphibolite partly mineralized with massive sulphides. The weakly arcuate geometry of this anomaly and of the Bouguer anomaly caused by the Fornás Unit may reflect the NE flank of the Central Iberian arc, an orocline whose core is occupied by the allochthonous complexes.FEDER, Ministerio de Ciencia e Innovación (Ramón y Cajal

Educating Future Agricultural Engineers at the University of Burgos, Spain, through a Service-Learning Project on Rural Depopulation and Its Social Consequences

A Service-Learning Project (S-LP) is a teaching experience through which the concepts covered during an educational course can practically be applied to address a given social problem. It is therefore a useful teaching methodology to bring courses closer to the real world. An S-LP experience is reported in this paper that was conducted with students of agricultural engineering to address the problem of rural depopulation, through the design of agri-food buildings for industries, and economic activities that help to maintain a stable population. After the S-LP, a survey was administered to both students and teachers, to assess the success of this teaching experience. The responses of the students showed not only an awareness of the social problem that was addressed, but also a critical spirit that led them to seek the best possible answer, and a global vision of the issue. It helped them to reflect on all of its facets to arrive at a way of engaging with the social problem. Importantly, the students were able to reflect upon how engineers can also serve society through their technical knowledge. The teachers indicated that the S-LP motivated the students on the course, while enabling them to successfully learn the concepts, and to develop independent study skills searching for information. In general, an S-LP is an experience that the teachers in this study would recommend and that could be especially relevant for universities assuming a role as a social entity to heighten the visibility of social problems and needs.This research was funded by The University of Burgos through the funding program “III Convocatoria de Proyectos de Innovación Docente y Transformación Social en Aprendizaje y Servicio (ApS) para el Curso Académico 2021–2022”. Furthermore, Javier Manso-Morato was funded by the Spanish Ministry MCIU, AEI and ERDF, grant FPU21/04364

Pre-Cenomanian versus Cenozoic folding in the High Atlas revealed by palaeomagnetic data

Palaeomagnetic data, and specifically remagnetizations, are used to constrain the geometric reconstruction at 100 Ma of three anticlines cored by gabbroic intrusions and Triassic shales in the Central High Atlas, Morocco. Previous palaeomagnetic results have revealed that the Mesozoic sediments of this region acquired a pervasive remagnetization at the end of the Early Cretaceous. The restoration of palaeomagnetic vectors to the remagnetization stage (100 Ma) allows us to determine the dip of the beds during this period and, thereby, to reconstruct structures during that time and determine the relative contributions of Mesozoic magmatic/diapiric uplift vs. Cenozoic compression to the present-day dip. Our results indicate that three major anticlines in the Central High Atlas (Tasraft, Tassent and Tissila) were initiated to different degrees before the Late Cretaceous and were reactivated during Cenozoic compression to acquire their present-day geometry. We also discuss the origin of these structures

La preservación del registro arqueomagnético en estructuras de combustión experimentales con 2 y 5 años de antigüedad

Trabajo presentado en: Magiber XI, 4-7 de septiembre de 2019, Condeixa a NovaJCYL-EFRD project BU235P18 and the MINECO-EFRD projects HAR2015-68321-P and CGL2016-77560, as well as the ERC Consolidator Grant project PALEOCHAR (648871