Calcarenitas con Microcodium del Paleoceno inferior en áreas hemipelágicas de la Zona Subbética, SE de España: isótopos de Sr, área fuente e implicaciones paleogeográficas

The Danian−early Selandian Olivares and Majalcorón formations are two calcarenite units rich in Microcodium remains that were accumulated in a marine hemipelagic setting of the Subbetic Zone (Betic Cordillera, southern Spain). Their outcrops are restricted to relatively small areas surrounded by uplifted Jurassic calcareous massifs, some of them with volcanic intercalations. The calcarenites contain lithoclasts of Lower Jurassic and lowermost Cretaceous age, and the 87 Sr/ 86 Sr isotopic ratios of the Microcodium remains suggest that they were originated in roots of plants that grew on Lower Jurassic carbonates. These facts entail that the Microcodium remains came from the calcareous massifs adjacent to their outcrops, the upper parts of which were subaerially exposed and colonized by Microcodium -producing plants during the Danian−early Selandian interval. The subaerial exposure of these massifs may have resulted from a coeval tectonic reactivation of Mesozoic syn-rift faults and folds, a eustatic sea level fall, or a combination of both processesLas formaciones Olivares y Majalcorón del Daniense-Selandiense inferior son unidades de calcarenitas ricas en restos de Microcodium acumuladas en un ambiente marino hemipelágico de la Zona Subbética (Cordillera Bética). Sus afloramientos están restringidos a áreas relativamente pequeñas rodeadas por elevados macizos de carbonatos jurásicos, algunos de ellos con intercalaciones volcánicas. Las calcarenitas contienen litoclastos del Jurásico Inferior y de la parte más baja del Cretácico, y los valores isotópicos 87 Sr/ 86 Sr de los restos de Microcodium sugieren que los mismos se originaron en raíces de plantas que crecían sobre carbonatos del Jurásico Inferior. Estos hechos implican que los restos de Microcodium proceden de los macizos carbonatados adyacentes a sus afloramientos, cuyas partes superiores estarían expuestas subaéreamente y colonizadas por plantas productoras de Microcodium durante el Daniense-Selandiense inferior. La exposición subaérea de dichos macizos pudo deberse a una reactivación tectónica de fallas y pliegues mesozoicos preexistentes, a un descenso eustático del nivel del mar, o a una combinación de ambos proceso

Calcareous nannofossil biostratigraphic analysis of the lower Eocene of the Barinatxe section (Western Pyrenees)

The Barinatxe section (Western Pyrenees) contains one of the most complete and expanded deep-water succession of the early Eocene so far described. The succession, cropped out continuously along sea cliffs, is rich in well preserved calcareous nannofossil. The calcareous nannofossil study carried out in Barinatxe section, where a total of 70 autochthonous early Eocene calcareous nannofossil species have been identified, has allowed us to identify Zones NP10, NP11, NP12 and NP13. Furthermore, we have precisely pinpointed the succession of calcareous nannofossil biohorizons and their relative position within the planktic foraminifer zones. The calcareous nannofossil and planktic foraminifer intercalibration scheme resulted from this study does not agree with the current standard biomagnetochronologic correlation scheme. In order to corroborate or contradict our observations similar studies in sections of a wide range of latitudes and depositional environments are neede

Environmental effect of astronomical climate change on lower Eocene hemipelagic deposits (Sopelana, Biscay)

Las sucesiones eocenas expuestas en Sopelana (Bizkaia) están caracterizadas por la alternancia de calizas y margas hemipelágicas que se organizan en trece grupos, cada uno con cinco pares caliza-marga. Esta organización sugiere que la formación de los pares estuvo controlada por ciclos astronómicos de precesión (20 ka) y la de los grupos por ciclos de excentricidad (100 ka). Se ha estudiado el contenido en carbonato y los isótopos estables de carbono y oxígeno de los pares del duodécimo grupo, a fin de descifrar los cambios ambientales en medios marinos profundos provocados por los ciclos de precesión y excentricidad y determinar las diferentes configuraciones orbitales que condujeron a la formación de cada capa.The Eocene successions exposed in Sopelana (Biscay) are characterized by the alternation of hemipelagic limestones and marls organized in thirteen distinctive bundles, each of which contains five limestone-marl couplets. Such an arrangement suggests that the formation of the couplets was driven by astronomical precession cycles (20 ky each) and that of the bundles by eccentricity cycles (100 ky). The couplets within the twelfth bundle were analysed for their carbonate content and their oxygen and carbon stable isotopes, with the aim of deciphering accurately the deep-sea environmental changes caused by the precession and eccentricity cycles and the varying orbital configurations that led to the formation of each be

The effects of astronomically forced climate change on hemipelagic carbonate sedimentation in a tectonically active setting: the Albian Mioño Formation in Castro Urdiales (Cantabria, N Spain)

Our understanding of the stratigraphic expression of astronomically driven climate-change cycles in the Milankovitch frequency band has improved significantly in recent decades. However, several aspects have been little studied to date, such as the nature of the climatically regulated environmental processes that ultimately control cyclic sedimentation. Similarly, relatively little is known about the expression of Milankovitch cycles in successions accumulated in tectonically active basins. In order to fill this knowledge gap, the Albian hemipelagic deposits of the Miono Formation exposed in Castro Urdiales (Basque-Cantabrian Basin) are studied herein. These deposits were accumulated during a rifting phase with strong tectonic activity. The sedimentological, petrographic and cyclostratigraphic analysis demonstrates that, despite the synsedimentary tectonic instabilities and some diagenetic overprinting, the hemipelagic carbonate alternation was astronomically forced 110.68-110.47 Ma. Seasonality fluctuations driven by precession cycles caused periodic (20 ky) variations in the rate of carbonate productivity (abundance of pelagic calcareous plankton and micrite exported from adjacent shallow-water areas) and/or siliceous dilution (terrestrially derived siliciclastic sediment supply and siliceous particle production by sponges). These variations resulted in the formation of marly limestone beds when annual seasonality was low (i.e., boreal summer at aphelion, winter at perihelion) and the accumulation of marlstones when seasonality increased (i.e., boreal summer at perihelion, winter at aphelion). The incidence of these processes increased and decreased in line with seasonality modulation by short-eccentricity cycles of 100 ky. In conclusion, this study shows that Milankovitch cycles can be reliably recorded in hemipelagic successions accumulated in tectonically active settings if sediment gravity flows or other disturbances do not affect autochthonous sedimentation.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Research funded by the MCIN/AEI project PID2019-105670GB-I00/AEI/10.13039/501100011033 of the Spanish Government and by the Consolidated Research Group IT160222 of the Basque Government

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

Systematics of Lutetian larger foraminifera and magneto-biostratigraphy from the South Pyrenean Basin (Sierras Exteriores, Spain)

A systematic description of the Eocene larger foraminifera recorded in the South Pyrenean Basin (Sierras Exteriores) is presented herein. The large dataset provided in this work includes Nummulites and Alveolina species, along with a variety of other porcellaneous and hyaline taxa with lesser biostratigraphic relevance. Most of the larger foraminifera described in this work correspond to the Lutetian (SBZ13 to SBZ16 biozones) interval, but late Ypresian (SBZ11, Cuisian) and early Bartonian (SBZ17) shallow benthic zones have also been identified. A new species, Idalinaosquetaensis, is described. The systematic revision of middle to late Lutetian alveolines led to a reassessment of Alveolinafusiformis and the finding of two new precursor forms, described as Alveolina aff. fragilis and Alveolina aff. elongata. The new taxa fill in the gap existing so far in the middle to late Lutetian alveolinid biostratigraphy. Despite not being exclusive to SBZ16, these forms provide realiable biostratigraphic information in facies where Nummulites are not present. This realibility lies on the correlation of Nummulitesand Alveolina biostratigraphic markers in the same sections and their calibration to the global time scale through magnetostratigraphy. Magnetostratigraphic calibration of described taxa is provided, along with an update of the SBZ calibration to the Geological Time Scale (Gradstein et al., 2012).&nbsp

Systematics of Lutetian larger foraminifera and magneto-biostratigraphy from the South Pyrenean Basin (Sierras Exteriores, Spain)

An extense systematic description of the Eocene larger foraminiferal faunas recorded in the South Pyrenean Basin (Sierras Exteriores) is presented herein. The large dataset provided in this work includes both Nummulites and Alveolina species, along with a variety of other porcellaneous and hyaline taxa with lesser biostratigraphic relevance, are represented. The larger foraminifera described in this work correspond mainly to the Lutetian (SBZ13 to SBZ16 biozones) interval, but late Ypresian (SBZ11, Cuisian) and Bartonian (SBZ17) shallow benthic zones have also been identified. As one of the most relevant results of this systematic analysis, a new species, Idalina osquetaensis, is described. The systematic revision of middle to late Lutetian alveolines led to a reassessment of A. fusiformis and the finding of two new precursor forms, described as affinis of their corresponding species, A. aff. fragilis and A. aff. elongata. The new forms A. aff. elongata and A. aff. fragilis fill the gap in the middle to late Lutetian alveolinid biostratigraphy. Despite not being exclusive to SBZ16, these new forms provide realiable biostratigraphic information where Nummulites are not present. This realibility lies on the correlation of Nummulites and Alveolina biomarkers in the same sections and their calibration to the global time scale through magnetostratigraphy. In fact, magnetostratigraphic calibration of all described taxa is also provided, along with an update of the SBZ calibration to the current Geologic Time Scale (Gradstein et al., 2012)

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.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

Nuevos datos sobre las faunas marinas del Eoceno medio-superior de Navarra (área surpirenaica occidental). Revisión de los fósiles de la colección Ruiz de Gaona

During Eocene times the Pyrenean area may have played an important role as a paleobiogeographic link between the Western Tethys and the North Atlantic domains. However, its marine faunas are still poorly documented. This paper presents the results of a first study on the mid–upper Eocene (Lutetian to Priabonian) marine macrofossils of Navarre included in the paleontological collection of Máximo Ruiz de Gaona, a researcher whose studies on the geology and paleontology of this territory constitute an obligatory historical reference. The described fossils come from the Eocene marly formations of the Pamplona basin and the Urbasa-Andia limestone Formation and overlying deposits, in the Estella-Urbasa area, west of the Pamplona fault. Some of the specimens studied come from outcrops that do not exist any longer. This fact increases the interest of conservation and the study of this collection. The paleontological data from the Estella-Urbasa area are almost entirely new. This study has allowed the description of 24 taxa of marine macrofauna. Seven of them ─Cyclolitopsis patera, Funginellastraea barcelonensis, Pycnodonte rarilamella, Metacrinus sp., Triplacidia sp., in addition to an indeterminate Cyclostomatida bryozoan and an indeterminate Serpulidae annelid─ are new to the fossil record of Navarre. The macropaleontological associations described in this and previous works are not as diverse as those from other coeval European geological regions. In addition to possible ecological conditions, sampling biases and, above all, taphonomic biases, specifically the loss of invertebrate species with aragonite skeletons, arise as the main explanation.Durante el Eoceno el área pirenaica pudo desempeñar un papel importante como encrucijada paleobiogeográfica entre los dominios del Tetis occidental y el Atlántico norte. Sin embargo, sus faunas marinas están todavía poco documentadas. En este trabajo se presentan los resultados de un primer estudio sobre los macrofósiles marinos del Eoceno medio–superior (Luteciense–Bartoniense–Priaboniense) de Navarra de la colección paleontológica de Máximo Ruiz de Gaona, investigador cuyos estudios sobre la geología y paleontología de este territorio constituyen una referencia histórica obligada. Los fósiles descritos provienen de las formaciones margosas del Eoceno de la cuenca de Pamplona y de la Formación Calizas de Urbasa-Andia y niveles suprayacentes, en el área de Estella-Urbasa, al oeste de la falla de Pamplona. Algunos de los especímenes estudiados provienen de afloramientos ya desaparecidos, circunstancia que aumenta el interés de la conservación y estudio de esta colección. Además, los datos paleontológicos del área de Estella–Urbasa son casi del todo novedosos. Este estudio ha permitido describir 24 taxones de macrofauna marina. Siete de ellos ─Cyclolitopsis patera, Funginellastraea barcelonensis, Pycnodonte rarilamella, Metacrinus sp., Triplacidia sp., además de un briozoo Cyclostomatida y un anélido Serpulidae indeterminados─ son nuevos para el registro fósil de Navarra. Las asociaciones macropaleontológicas descritas aquí y en otros trabajos precedentes son poco diversas si se las compara con las coetáneas de otras regiones geológicas europeas. Además de posibles condicionamientos ecológicos, se plantea la existencia de sesgos de muestreo y, sobre todo de sesgos tafonómicos, en concreto, la pérdida de las especies de invertebrados con esqueletos aragoníticos, como principal explicación de este hecho