Development and significance of tectonic foliations in the Hercynian Belt of NW Spain

[Resumen] En este trabajo se presenta un modelo de distribución y desarrollo de foliaciones en rocas pelíticas y samíticas dentro de un orógeno: el Macizo Herciniano del NW d e España. Estas rocas estuvieron sometidas a una deformación polifásica, con tres fases principales, en condiciones que van desde la transición diagénesis-metamorfismo hasta un metamorfismo de alto grado. Las características de las foliaciones asociadas a las distintas fases de deformaci6n varían progresivamente a medida que lo hace el metamorfismo, existiendo, no obstante, algunos saltos bruscos en dichas características, cuya situaci6n coincide con los límites entre algunas de las grandes zonas en que se divide el orógeno. En todo caso, la foliación tect6nica primaria(Sl) muestra un carácter generalizado, mientras que las otras dos (S2 y S3) presentan una distribución más irregular, apareciendo la S2 en relación con las zonas de cizalla asociadas a grandes cabalgamientos y la S3 controlada por la posición de la anisotropía previa dominante. En la formaci6n de estas foliaciones intervino, en general, de manera muy importante la disolución por presión en las áreas menos metamórficas y la recristalización orientada de filosilicatos en las más metamórficas. El análisis de las relaciones cronológicas entre cristalización metamórfica y desarrollo de foliaciones pone de manifiesto una cierta heterogeneidad espacial en el momento de aparición de los episodios metamórficos en relación con los de deformación. Esta heterogeneidad puede explicarse por las alteraciones en las condiciones P, T que produce el emplazamiento de las grandes unidades tectónicas.[Abstract] A model concerning distribution and development of foliations is presented in this paper, for pelitic and psammitic rocks in the Hercynian Belt ofNW Spain. This rocks have undergone three main deformation phases, in conditions ranging from the iagenesis-metamorphism transition to the high grade metamorphism. The features of the foliations associated to the different phases varie progressively with the metamorphism. Nevertheless, sorne abrupt changes in this features can also be found in sorne of the borders between the main tectonic units. Anyhow, the primary tectonic foliation (Si) is generalized, and the other two (S2 and S3) have a more irregular distribution, related to shear zones associated to main thrusts (S2), or to zones with a favourable possition of the main previous anisotropy (for S3)' The deformation mechanisms opperating in the development of this foliations were, mainly, pressure solution in the zones with low metamorphism, and recrystalization of orientated phyllosillicates in those with the higher metamorphism. The analysis of the chronologic relationships between metamorphic crystalization and development of the foliations in different tectonic units shows sorne differences in the age of the metamorphic episodes in relation with the deformation. These inhomogeneities can be explained by the changes in P, T conditions produced by the emplacement of the main tectonic units

Alpine tectonic wedging and crustal delamination in the Cantabrian Mountains (NW Spain)

The Cantabrian Mountains have been interpreted as a Paleozoic basement block uplifted during an Alpine deformation event that led to the partial closure of the Bay of Biscay and the building of the Pyrenean range in the Cenozoic. A detailed interpretation of deep seismic reflection profile ESCIN-2 and the two-dimensional seismic modelling of the data allowed us to construct a N-S geological cross section along the southern border of the Cantabrian Mountains and the transition to the Duero Cenozoic foreland basin, highlighting the Alpine structure. The proposed geological cross section has been constrained by all geophysical data available, including a 2-D gravity model constructed for this study as well as refraction and magnetotelluric models from previous studies. A set of south-vergent thrusts dipping 30 to 36° to the north, cut the upper crust with a ramp geometry and sole in the boundary with the middle crust. These thrusts are responsible for the uplift and the main Alpine deformation in the Cantabrian Mountains. A conspicuous reflective Moho shows that the crust thickens northwards from the Duero basin, where subhorizontal Moho is 32 km deep, to 47 km in the northernmost end of ESCIN-2, where Moho dips to the north beneath the Cantabrian Mountains. Further north, out of the profile, Moho reaches a maximum depth of 55 km, according to wide-angle/refraction data. ESCIN-2 indicates the presence of a tectonic wedge of the crust of the Cantabrian margin beneath the Cantabrian Mountains, which is indented from north to south into the delaminated Iberian crust, forcing its northward subduction. © 2016 Author(s).This study was part of the PhD thesis of J. Gallastegui and was supported by a FPU grant and research projects GEO 90-0660-1086 and PB92-1013 funded by CICYT (Committee of Science and Technology of the Spanish Ministry of Education and Science) and FICYT (Foundation for the Science and Technologic Research, Government of Asturias, Spain). Part of the study has also been financed by the Spanish Ministry of Science through the “TOPOIBERIA” Consolider Project (ref:MEC-06-CSD2006-0041) and the MISTERIOS Project (ref:MINECO-13-CGL2013-48601-C2).Peer reviewe

Nuevas aportaciones al conocimiento de la evolución tectonometamórfica del complejo de Cabo Ortegal (NW de España)

[Resumen] El Complejo de Cabo Ortegal es una unidad a16ctona constituida en gran parte por rocas ultrabásicas, básicas y neises. Estas rocas han sufrido un metamorfismo polifásico en el que se distinguen cuatro episodios, de forma que el grado más elevado se alcanza durante la primera fase (facies granulita y eclogita), teniendo lugar después una retrogradación progresiva hasta la facies de los esquistos verdes. La evolución de la deformación ha tenido también lugar en cuatro fases, de forma que la primera es posterior a los dos primeros episodios metamórficos. Las tres primeras fases de deformación representan una importante deformación por cizalla tangencial, mientras que la cuarta da lugar al amplio sinforme en cuyo núcleo se sitúa el complejo. Las rocas de Cabo Ortegal representan probablemente una secuencia ofiolítica subducida durante el Ordov!cico y obducida con posterioridad al Devónico inferior como con secuencia de una colisión continental.[Abstract] The Cabo Ortegal Complex is an allochthonous unit made up of ultrabasic rocks, basic rocks and gneisses. These rocks have suffered a poliphasic metamorphism in which four episodes can be established. The highest degree of metamorphism (granulitic and eclogitic facies) took place during the first phase followed a~erwards by a progressive retrogresion to greenschist facies. Four phases of deformation can also be distinguished being the first later than the first two metamorphic episodes. The three earlier tectonic phases represent an important sheardeformation while the forth gives way to the wide sinform of Cabo Ortegal. The rocks of the Cabo Ortegal Complex would be an ophiolitic sequence subducted during Ordovician times and obducted after the lower Devonian, due to a continental collision

Acclimatization to chronic intermittent hypoxia in mine workers: a challenge to mountain medicine in Chile

In the past two decades, Chile has developed intense mining activity in the Andes mountain range, whose altitude is over 4,000 meters above sea level. It is estimated that a workforce population of over 55,000 is exposed to high altitude hypobaric hypoxia. The miners work under shift systems which vary from 4 to 20 days at the worksite followed by rest days at sea level, in a cycle repeated for several years. This Chronic Intermittent Hypoxia (CIH) constitutes an unusual condition for workers involving a series of changes at the physiological, cellular and molecular levels attempting to compensate for the decrease in the environmental partial pressure of oxygen (PO2). The mine worker must become acclimatized to CIH, and consequently undergoes an acute acclimatization process when he reaches the worksite and an acute reverse process when he reaches sea level. We have observed that after a period of 3 to 8 years of CIH exposure workers acclimatize well, and evidence from our studies and those of others indicates that CIH induces acute and chronic multisystem adjustments which are effective in offsetting the reduced availability of oxygen at high altitudes. The aims of this review are to summarize findings of the physiological responses to CIH exposure, highlighting outstanding issues in the field

Cell death in hepatocellular carcinoma: Pathogenesis and therapeutic opportunities

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer and the third leading cause of cancer death worldwide. Closely associated with liver inflammation and fibrosis, hepatocyte cell death is a common trigger for acute and chronic liver disease arising from different etiologies, including viral hepatitis, alcohol abuse, and fatty liver. In this review, we discuss the con-tribution of different types of cell death, including apoptosis, necroptosis, pyroptosis, or autophagy, to the progression of liver disease and the development of HCC. Interestingly, inflammasomes have recently emerged as pivotal innate sensors with a highly pathogenic role in various liver diseases. In this regard, an increased inflammatory response would act as a key element promoting a pro-oncogenic microenvironment that may result not only in tumor growth, but also in the formation of a premetastatic niche. Importantly, nonparenchymal hepatic cells, such as liver sinusoidal endothelial cells, hepatic stellate cells, and hepatic macrophages, play an important role in establishing the tumor microenvironment, stimulating tumorigenesis by paracrine communication through cytokines and/or angiocrine factors. Finally, we update the potential therapeutic options to inhibit tumorige-nesis, and we propose different mechanisms to consider in the tumor microenvironment field for HCC resolution. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

From the North-Iberian Margin to the Alboran Basin: A lithosphere geo-transect across the Iberian Plate

A ~ 1000-km-long lithospheric transect running from the North-Iberian Margin to the Alboran Basin (W-Mediterranean) is investigated. The main goal is to image the changes in the crustal and upper mantle structure occurring in: i) the North-Iberian margin, whose deformation in Alpine times gave rise to the uplift of the Cantabrian Mountains related to Iberia-Eurasia incipient subduction; ii) the Spanish Meseta, characterized by the presence of Cenozoic basins on top of a Variscan basement with weak Alpine deformation in the Central System, and localized Neogene-Quaternary deep volcanism; and iii) the Betic-Alboran system related to Africa-Iberia collision and the roll-back of the Ligurian-Tethyan domain. The modeling approach, combines potential fields, elevation, thermal, seismic, and petrological data under a self-consistent scheme. The crustal structure is mainly constrained by seismic data whereas the upper mantle is constrained by tomographic models. The results highlight the lateral variations in the topography of the lithosphere-asthenosphere boundary (LAB), suggesting a strong lithospheric mantle strain below the Cantabrian and Betic mountain belts. The LAB depth ranges from 180 km beneath the Cantabrian Mountains to 135-110. km beneath Iberia Meseta deepening again to values of 160. km beneath the Betic Cordillera. The Central System, with a mean elevation of 1300. m, has a negligible signature on the LAB depth. We have considered four lithospheric mantle compositions: a predominantly average Phanerozoic in the continental mainland, two more fertile compositions in the Alboran Sea and in the Calatrava Volcanic Province, and a hydrated uppermost mantle in the North-Iberian Margin. These compositional differences allowed us to reproduce the main trends of the geophysical observables as well as the inferred P- and S-wave seismic velocities from tomography models and seismic experiments available in the study transect. The high mean topography of Iberia can be partly consistent with a low-velocity/high-temperature/low-density layer in the sublithospheric mantle.The presented work has been supported by Topo-Iberia Consolider-IngenioCSD2006-0004, GASAM/TopoMed (CGL2008-03474-E/BTE/07-TOPO-EUROPE-FP-006), TECLA (CGL2011-26670) funded by the Spanish Government, and PYRTEC-IP2 (SV-PA-10-03, funded by the Government of Asturias/ESF TOPO-EUROPE Programme) projects. AC benefitted from a JAE-PreCP grant from CSIC. JCA acknowledges the support from ARC GrantDP120102372.Peer Reviewe