El sistema turbidítico conglomerático de Andatza (Pirineos occidentales): Estratigrafía, sedimentología y control estructural

This is a field-based work that describes the stratigraphy and sedimentology of the Andatza Conglomerate Formation. Based on facies analysis three facies associations of a coarse-grained turbidite system and the related slope have been identified: (1) an inner fan of a turbidite system (or canyon) and (2) a low- and (3) a high-gradient muddy slope respectively. The spatial distribution of the facies associations and the palaeocurrent analysis allow to interpret a depositional model for the Andatza Conglomerates consisting of an L-shaped, coarse-grained turbidite system, whose morphology was structurally controlled by synsedimentary basement-involved normal faults. The coarse-grained character of the turbidite system indicates the proximity of the source area, with the presence of a narrow shelf that fed the turbidite canyon from the north.En este trabajo se describe la estratigrafía y sedimentología de la Formación Conglomerados de Andatza. Mediante el análisis de facies se han interpretado tres asociaciones de facies principales correspondientes a un sistema turbidítico (de grano grueso) y al talud: un sistema turbidítico interno (o cañón), un talud fangoso de alto gradiente y otro de bajo gradiente. La distribución cartográfica de las asociaciones de facies junto con el análisis de paleocorrientes describen un modelo sedimentario de sistema turbidítico de grano grueso en forma de “L” para los Conglomerados de Andatza, cuya morfología fue controlada por fallas normales sinsedimentarias de basamento. El carácter grosero del tamaño de grano de este sistema turbidítico indica la proximidad del área fuente de los conglomerados, que alimentaría el cañón turbidítico desde el norte a través de una estrecha plataforma marina

Rift-margin extensional forced folds and salt tectonics in the eastern Basque-Cantabrian rift basin (western Pyrenees)

In this paper we present and discuss Cretaceous extensional folds of the eastern Basque-Cantabrian Basin (Northern Spain). Geometry and kinematics of folds is constrained by means of structural and sedimentological fieldwork integrated with geological mapping, revealing an intimate link between coeval folding, extensional faulting, and salt mobilization. In detail, the Mesozoic succession of the northwestern and southern borders of the Palaeozoic Bortziriak-Cinco Villas massif (eastern margin of the BCB) host late Albian–early Cenomanian syn-rift forced folds. The studied forced fold axes trend parallel and are located above main and inferred Cretaceous syn-sedimentary basement faults. Structural data indicate that these folds formed during the late Albian − early Cenomanian interval. The presence of Upper Triassic clay and evaporite outcrops along and/or close to the axes of folds and their stratigraphic relationship with Upper Cretaceous strata indicate their halokinetic origin and extrusion during folding. The trigger of salt tectonics is attributed to a basement extensional pulse during the Bay of Biscay – Pyrenean rifting. Related high subsidence-rates allowed salt to flow towards faults, forming salt walls and causing the inflation and folding of the overburden.grant BFI05.398 from the Basque Government to A. Bodego and grant AP98-44159606 from the Spanish Science Ministry to E. Iriarte. Funds were also supplied by Ministerio de Educación y Ciencia (MEC) – Ministerio de Ciencia e Innovación (MICINN) (projects CGL2006-05491/BTE and CGL2009-08545) and Euskal Herriko Unibertsitatea (UPV/EHU) (projects EHU06/62, UNESCO06/03 and EHUA15/18

Caracterización y bioestratigrafía de foraminíferos planctónicos de la transición del Grupo Flysch Negro - Flysch Calcáreo entre Usurbil y Hernani, Pirineo occidental

La realización de una cartografía de detalle junto al análisis sedimentológico y bioestratigráfico del contacto entre las unidades del Grupo Flysch Negro y el Flysch Calcáreo entre las localidades de Usurbil y Hernani ha permitido caracterizar el tránsito entre ambas unidades estratigráficas. Los datos indican la existencia de una disconformidad entre ambas unidades y no un contacto por falla inversa tal y como habían sugerido autores anteriores. Un análisis bioestratigráfico de detalle de las rocas subyacentes y suprayacentes al contacto deposicional indica la presencia de un hiato de duración variable a lo largo del mismo: en el sector oeste un hiato intra-Zona R. globotruncanoides (Cenomaniense Inferior) y en el sector este un hiato entre las Zonas R. appenninica – R. globotruncanoides (Albiense Superior-Cenomaniense Inferior

Rift-margin extensional forced folds and salt tectonics in the eastern Basque-Cantabrian rift basin (western Pyrenees)

In this paper we present and discuss Cretaceous extensional folds of the eastern Basque-Cantabrian Basin (Northern Spain). Geometry and kinematics of folds is constrained by means of structural and sedimentological fieldwork integrated with geological mapping, revealing an intimate link between coeval folding, extensional faulting, and salt mobilization. In detail, the Mesozoic succession of the northwestern and southern borders of the Palaeozoic Bortziriak-Cinco Villas massif (eastern margin of the BCB) host late Albian–early Cenomanian syn-rift forced folds. The studied forced fold axes trend parallel and are located above main and inferred Cretaceous syn-sedimentary basement faults. Structural data indicate that these folds formed during the late Albian − early Cenomanian interval. The presence of Upper Triassic clay and evaporite outcrops along and/or close to the axes of folds and their stratigraphic relationship with Upper Cretaceous strata indicate their halokinetic origin and extrusion during folding. The trigger of salt tectonics is attributed to a basement extensional pulse during the Bay of Biscay – Pyrenean rifting. Related high subsidence-rates allowed salt to flow towards faults, forming salt walls and causing the inflation and folding of the overburden.This research was funded by grant BFI05.398 from the Basque Government to A. Bodego and grant AP98-44159606 from the Spanish Science Ministry to E. Iriarte. Funds were also supplied by Ministerio de Educación y Ciencia (MEC) – Ministerio de Ciencia e Innovación (MICINN) (projects CGL2006-05491/BTE and CGL2009-08545) and Euskal Herriko Unibertsitatea (UPV/EHU) (projects EHU06/62, UNESCO06/03 and EHUA15/18)

Influence of salt-antiform growth on a mid-Cretaceous braidplain delta system: Oiartzun Formation, NE margin of the Basque-Cantabrian Basin

Los depósitos siliciclásticos y carbonatados de la Formación Oiartzun (Albiense superior-Cenomaniense inferior) al sureste de Donostia-San Sebastián (margen NE de la Cuenca Vasco-Cantábrica) registran la evolución de la formación de pliegues forzados causados por la tectónica salina coetánea dentro de un contexto de rifting . El análisis de facies indica la localización espacial de distintos ambientes sedimentarios dentro de un sistema deposicional de tipo braidplain delta en un espacio relativamente reducido debido a la evolución y formación de los antiformes de Txoritokieta y Oiartzun. Asimismo, el crecimiento de estos pliegues modifica el relieve deposicional, condicionando notablemente el espesor estratigráfico sobre cada uno de los flancosThe siliciclastic and carbonate deposits of the upper Albian to lower Cenomanian Oiartzun Formation, which crop out to the southeast of Donostia-San Sebastián (NE margin of the Basque-Cantabrian Basin), record the evolution of the coeval growth of salt-influenced forced-folds (anticlines), in an extensional rifting context. Facies analysis indicates the distinct spatial distribution of sedimentary environments in a braidplain delta depositional system over a relatively reduced area, due to the synsedimentary growth of the Txoritokieta and Oiartzun forcedfolds. The growth of these folds conditions the depositional relief and impact not only in the facies distribution but also in stratigraphic thicknesses in the fold limb

Análisis de la enseñanza de los procesos geológicos externos en la educación secundaria obligatoria del País Vasco

Los expertos han constatado una pérdida de interés hacia la geología de la población en general que podría estar relacionada con su exclusión progresiva en el currículo básico en la educación obligatoria. Sin embargo, es necesario que el alumnado que finaliza la Educación Secundaria Obligatoria (ESO) adquiera una correcta alfabetización en Ciencias de la Tierra, en la que entender los procesos geológicos externos y su acción en el relieve es un contenido clave. Este estudio ha evaluado qué procesos geológicos externos se enseñan en la ESO de la Comunidad Autónoma del País Vasco, mediante el análisis de los libros de texto más utilizados y la realización de cuestionarios al profesorado. Ambas fuentes revelan que el estado actual de su enseñanza muestra deficiencias y necesita mejoras, tales como dedicarle el tiempo y espacio que le corresponde o mejorar la calidad de los textos empleados. Palabras clave: Geología, Procesos geológicos externos, Educación Secundaria Obligatoria, Libros de texto, Docentes. Analysis of teaching external geological processes in the compulsory secondary school of the Autonomous Community of the Basque Country Abstract: Experts have noted that the interest of the general population in geology has decreased. This seems to be related to an exclusion of geology from compulsory education curriculum. However, it is mandatory that the students who complete compulsory secondary school acquire a correct literacy in Earth Sciences, in which understanding external geological processes and their action on the relief is a key content. Our study has evaluated which external geological processes are taught in the compulsory secondary school of the Autonomous Community of the Basque Country. To this end, the most commonly used textbooks were analyzed and teachers were asked to fill out questionnaires. Both sources reveal that the current teaching of this unit shows deficiencies and, consequently, needs improvement in both the quality of the texts used and in the time and space devoted to this unit. Keywords: Geology, Geomorphology, Secondary school, Text books, Teachers.Los expertos han constatado una pérdida de interés hacia la geología de la población en general que podría estar relacionada con su exclusión progresiva en el currículo básico en la educación obligatoria. Sin embargo, es necesario que el alumnado que finaliza la Educación Secundaria Obligatoria (ESO) adquiera una correcta alfabetización en Ciencias de la Tierra, en la que entender los procesos geológicos externos y su acción en el relieve es un contenido clave. Este estudio ha evaluado qué procesos geológicos externos se enseñan en la ESO de la Comunidad Autónoma del País Vasco, mediante el análisis de los libros de texto más utilizados y la realización de cuestionarios al profesorado. Ambas fuentes revelan que el estado actual de su enseñanza muestra deficiencias y necesita mejoras, tales como dedicarle el tiempo y espacio que le corresponde o mejorar la calidad de los textos empleados. Palabras clave: Geología, Procesos geológicos externos, Educación Secundaria Obligatoria, Libros de texto, Docentes. Analysis of teaching external geological processes in the compulsory secondary school of the Autonomous Community of the Basque Country Abstract: Experts have noted that the interest of the general population in geology has decreased. This seems to be related to an exclusion of geology from compulsory education curriculum. However, it is mandatory that the students who complete compulsory secondary school acquire a correct literacy in Earth Sciences, in which understanding external geological processes and their action on the relief is a key content. Our study has evaluated which external geological processes are taught in the compulsory secondary school of the Autonomous Community of the Basque Country. To this end, the most commonly used textbooks were analyzed and teachers were asked to fill out questionnaires. Both sources reveal that the current teaching of this unit shows deficiencies and, consequently, needs improvement in both the quality of the texts used and in the time and space devoted to this unit. Keywords: Geology, Geomorphology, Secondary school, Text books, Teachers

Immunocytochemical evidence for growth hormone-releasing hormone in the tanycytes of the median eminence of the rat

The current study was performed to analyse the potential existence and structure of a GHRH-transporting tuberoinfundibular system in the rat median eminence. The immunocytochemical analysis using anti-GHRH revealed an intense immunoreaction in the ependimary cells, tanycytes, at the level of the floor of the infundibular recess forming part of the median eminence. The basal processes of these cells course towards the external layer of the median eminence and reach the growth hormone-releasing hormone (GHRH) fibres of the tuberoinfundibular tract and this reaction was increased after intraventricular treatment with colchicine. Thus, these observations suggest the existence of a second or alternative cerebrospinal fluid-mediated route of GHRH transport to the median eminence and implicate the involvement of tanycytes in the regulation of this novel transport system

Hiperestentsioa: kontinenteen apurketa ulertzeko eredu berri bat

Kontinenteen apurketa luzaroan ikertu den prozesu geologikoa da. Rifting deritzon prozesu horrek milioika urte irauten ditu, eta kontinente-ertzetan, mendikateetan eta bestelako ingurune geologikoetan topatzen dira fenomeno tektoniko horren aztarnak. Plaka tektonikoen banaketaren interpretazioa, ordea, eboluzionatuz doa ikertzaileen ulermenaren eta aurrerapen teknologikoen arabera. Hiperestentsioaren ideia da interpretazio horren azken berrikuntza. Ideia hori litosfera kontinentalaren deformazio polifasikoan barneratzen da, litosferaren muturreko luzapenean oinarrituz, hain zuzen. Ertz egonkorretan eta gerriko orogenikoetan identifikaturiko egitura geologiko eta eremu estruktural bereizgarriek ahalbidetzen dute fenomeno horren bilakaeraren nolakotasuna definitzea. Magman txiroak bezala ezagutzen diren ertz egonkorretako eremu horiek dira hurbileko domeinua, necking domeinua, urruneko domeinua edo hiperluzatua eta kanpoko domeinua. Domeinu horietako bakoitza riftingaren deformazio faseekin lotzen da; fase horiek litosfera kontinentalaren luzapena, mehetzea, mantuaren azaleratzea eta lurrazal ozeanikoaren zabaltzea dira. Esan bezala, iraganean hiperluzatutako arroetan ari da garatzen ikerketa, eta hipotesi horren bitartez ulertzen hasia da, honezkero, Euskokantauriar arroa (EKA) barneratzen duen Iberia eta Eurasia arteko Mesozoikoko rift-sistemaren garapena. Urteetan arroan bildutako datuek, behintzat, horretara bultzatzen dute. Pirinioen mendebaldean deskribaturiko mantuaren azaleratzeak eta arroan deskribaturiko hamaika prozesuk indartu dute Kretazeoko riftingean hiperestentsioak izan zezakeen garrantzia; azken horrek, gainera, garai hartako EKAren eboluzio geologikoaren paradigma argitu dezake.; Continental breakup is a geological process which has been deeply learnt. The keys of that tectonic phenomena, the so-called rifting process that lasts millions of years, can be found worldwide within rifted margins, mountain chains and other geological settings. However, the interpretation of tectonic plate rupture evolves while researcher´s comprehension and technology advance. Hyperextension is the last update within that interpretation. This revolutionary idea involves the extreme polyphasic extensional deformation of the continental lithosphere. Characteristic geological structures and structural domains identified within passive margins and orogenic belts, allow to define the evolution of this phenomena. Domains such as the proximal domain, necking domain, distal or hyperextended domain and outer domain are distinguishing features within magma poor rifted margins. These domains are linked to specific deformation phases during rifting, being stretching and thinning of continental lithosphere, mantle exhumation and oceanic crust spreading part of these process. As said, research is being carried out in hyperextended basins, and the evolution of the Iberia-Eurasia Mesozoic rift system, which involves the Basque-Cantabrian Basin (BCB), is already being understood within that hypothesis. Data collected over years in the BCB, at least, suggest that. Mantle exhumation described in the western Pyrenees and several processes linked to that within the BCB, reinforces the significance that hyperextension could have occurred during the Cretaceous rifting, shedding light to the paradigm concerning the evolution of the BCB

Cantera Gorria and Red Ereño: Natural and Cultural Geoheritage (Basque Country, Spain)

[EN] Construction and ornamental stones are important elements of cultural heritage and geoheritage. The quarries, where these materials are extracted, are a type of site that combines these two types of heritage. Both the ornamental character of the rock and its place of origin can be deeply rooted in the local society. Red Ereno is a red micritic limestone (Lower Cretaceous) with abundant white rudist fossil shells. This stone has been exploited since Roman times in the north of the Iberian Peninsula (Basque Country, Spain) and exported internationally. The main quarry related to the extraction of Red Ereno, Cantera Gorria, is currently a cultural and geoheritage site. This emblematic site brings together numerous geologic (palaeontological, petrological, geomorphological and tectonic) and mining features that make it a reference point for both research and teaching activities. The link between geoheritage and cultural heritage that exists in Cantera Gorria is evident and makes this place an essential point for dissemination of geology as well as for tourism. The quarry is currently abandoned, and because of this, there is an urgent need for its protection and development, and in order to increase awareness of its importance and potential use.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. UPV/EHU Research Group IT-029/16 (Government of the Basque Country)

First data of Cretaceous hydrothermalism in the eastern margin of the Basque-Cantabrian basin

In the Eastern margin of the Basque-Cantabrian Basin, fissures filled with sediments crop out in a red Albian-Cenomanian limestone, near the Txoritokieta mount (Errenteria, Gipuzkoa). In this work we study the sedimentology, petrology and tectosedimentary character of fissures and their fills, in order to establish the evolutive sequence of the formation of fractures and the infill of them. It has been inferred the tectonic origin of the fissures, linked to the synsedimentary folding of the host limestone. Moreover, most of the studied sedimentary fissure fills are mineralized, suggesting that fracturing and fluid flow occurred during the deposition of the fissure fillsEn el margen oriental de la Cuenca Vasco-Cantábrica afloran fisuras rellenas de sedimento encajadas en calizas rojas Albiense-Cenomaniense, en las inmediaciones del monte Txoritokieta (Errenteria, Gipuzkoa). El objetivo de este estudio ha sido estudiar las fracturas y sus rellenos desde el punto de vista sedimentológico, petrológico y tectosedimentario, para establecer la secuencia evolutiva de la formación de las fisuras rellenas. Así, se ha inferido el origen tectónico de las fracturas, ligado al plegamiento sinsedimentario de la propia formación que engloba las calizas encajantes. Asimismo, los rellenos de las fracturas, que se encuentran mineralizados en su gran mayoría, sugieren que su formación (fracturación) se localizó cerca de la superficie de sedimentación y la circulación de fluidos mineralizantes ocurrió en momentos próximos al depósito de los relleno