Caracterización estratigráfica de la serie sedimentaria del Valle del río Martín (área de Ariño-Albalate): causas de la evolución paleoambiental durante el Cuaternario

The middle course of the Martín River (a tributary of the Ebro River) is considered a very interesting area from a geological point of view and an important number of paleontological, mineralogical and sedimentological studies have been focused on it. In this work, the Quaternary deposits located in this part of the river between the towns of Ariño and Albalate del Arzobispo, have been analysed in detail in order to understand their sedimentary environment and their evolution. This study has compiled the necessary stratigraphic and cartographic information to establish the presence of two levels of terraces topographically located at a similar height over the current position of the river. The most important sedimentological facies associated to the studied deposits have been described and interpreted through the study of the stratigraphic profiles and the different laboratory analyses performed over the samples taken in the area. All this information has allowed to define four different stages in the valley evolution: two stages of deposit (fill in) and one of incision. The first filling in stage corresponds to the Upper Pleistocene; the second stage is associated to the Younger Dryas and represents the erosion of the previously deposited materials due to the fluvial incision; and the third stage, which would be related to the Holocen Climatic Optimum, corresponds to the second basin fill in. Finally another stage of incision over these deposits would be responsible for the present position of the Martín River

Segmentation and increasing activity in the Neogene-Quaternary Teruel Basin rift (Spain) revealed by morphotectonic approach

The NNW-SSE trending Teruel Basin rift is the largest Late Miocene-Quaternary extensional intracontinental structure located within the central-eastern Iberian Chain (Spain). The structural and morphotectonic study carried out in the central-northern part of this half graben basin (north of Teruel city) has allowed us to analyse rift segmentation, deformation partitioning and rift evolution. Results are based on vertical displacement calculations (fault throw and bending) of the main border and intrabasin fault zones. We use two geomorfological-stratigraphical markers, the Intramiocene Erosion Surface (IES; 11.2 Ma) and the Fundamental Erosion Surface (FES; 3.5 Ma). While the first marker reveals rift initiation under an E-W extension, the late marker records vertical displacements associated to a second, Late Pliocene–Quaternary rifting stage characterized by a nearly multidirectional extension regime with prevailing ENE-WSW trending ó3. Despite the along-axis rift segmentation into three structural domains (northern, central and southern) and the distribution of deformation among border and intrabasin faults in the central and southern domains, a consistent average slip rate (post-IES) of 0.09 mm/a has been calculated on distinct transects across the basin, suggesting a homogeneous crustal-scale extension process in the region. The results also reveal that slip rates during the Late Pliocene-Quaternary (0.12–0.16 mm/a) are higher than the Late Miocene-Early Pliocene (0.05–0.07 mm/a). Slip rate increase is caused by (i) a westward propagation of deformation from the Valencia Through, and (ii) a change in the regional stress field, both enhanced by crustal doming affecting central-eastern Iberia, as well as progressive fault linkage. Throw vs. distance graphs suggest that the main faults are in a transient stage towards coalescence, less advanced within the southern domain. Regional Late Pliocene-Quaternary uplift, concomitant with increasing slip rates in the Teruel Basin rift, has caused the basin to rise, so that synrift sedimentation only took place in rapidly subsiding residual basins until the region became exorheic and the basin was incised by the present-day fluvial network

A review of the European Neogene Mammal zones from integration of litho-, bio- and magnetostratigraphy in the Teruel Basin

The northern sector of the Teruel Basin (Spain) houses a dense and continuous record of late Neogene mammal fossil sites, as well as numerous biostratigraphic and magnetostratigraphic information making it a reference basin to define and refine the European mammal biostratigraphy from the Vallesian to the Villafranchian. The Neogene mammal chronology is in ongoing revision, and distinct correlations between basins and Europe provinces have been proposed based on their relative ages. New calibration methods based on numerical modelling have allowed the absolute ages of the paleontological sites to be refined. Nevertheless, some discrepancies arise, evidencing that ancho ring between absolute ages and mammal fossil record would benefit from a stronger stratigraphical framework. This work provides such a robust 3D stratigraphic framework of the whole basin that, together with magnetostratigraphy, allows establishing an accurate chronostratigraphic model and hence a precise chronology of sedimentary units and mammal sites. The absolute age of MN zones, or mammal stages, in the Teruel Basin has been revised on the basis of a detailed and confident stratigraphic correlation, and updated to the most recent Geomagnetic Polarity Time Scale. In particular, new accurate ages have been proposed for the boundaries MN 9/10 to MN 16/17 from data exclusively located in the Teruel Basin, with a precision generally of 0.1–0.2 Ma

Alluvial sedimentation and tectono-stratigraphic evolution in a narrow extensional zigzag basin margin (northern Teruel Basin, Spain)

The northern part of the eastern margin of the extensional Neogene Teruel Basin (central-eastern Spain) consists of a non-linear, zigzag fault zone made of alternating ca. 2 km long, NNW-SSE trending segments and shorter NNE-SSW ones. Good outcrop conditions made possible a comprehensive integrated stratigraphic and structural study, especially focused on coarse clastic sediments deposited along the basin margin. Well-exposed stratal relationships with boundary faults, allowed the analysis of tectonic influence on sedimentation. Synsedimentary deformation includes growth faulting, rollover anticlines, and monoclines and associated onlap stratal terminations, angular unconformities, and other complex growth strata geometries. One of them is the onlap-over-rollover bed arrangement described here for the first time, which reveals the competition between tectonic subsidence and sedimentary supply. Both, the structural inheritance (dense Mesozoic fracture grid) and the dominant, nearly ‘multidirectional’ (s1 vertical, s2 ˜ s3), Pliocene extensional regime with s3 close to E-W, are considered to have controlled the margin structure and evolution. Tectono-stratigraphic evolution includes: (i) reactivation of inherited NNW-SSE faults and development of W-SW-directed small alluvial fans (SAF) while NNE-SSW segments acted as gentle relay ramp zones; (ii) progressive activation of NNE-SSW faults and development of NW-directed very small alluvial fans (VSAF); during stages i and ii sediments were trapped close to the margin, avoiding widespread progradation; (iii) linking of NNW-SSE and NNE-SSW structural segments, overall basin sinking and widespread alluvial progradation; (iv) fault activity attenuation and alluvial retrogradation. The particular structure and kinematic evolution of this margin controlled alluvial system patterns. Size of alluvial fans, directly set up at the border faults, was conditioned by the narrowness of the margin, small catchment areas, and proximity between faults, which prevented the development of large alluvial fans. The size of the relay zones, only a few hundred meters wide, acted in the same way, avoiding them to act as large sediment transfer areas and large alluvial fans to be established. These features make the Teruel Basin margin different to widely described extensional margins models

Coupling far and near tectonic signals in syn-orogenic sediments : the Olvena growth strata (Sierras Marginales, southern Pyrenees)

The Olvena area (Sierras Marginales, southern Pyrenees) provides an outstanding example for studying the relationships between tectonics and sedimentation related to fold-and-thrust systems having shallow décollements. Stratigraphic and sedimentological features allow infer i) the relationship between Oligocene-Miocene locallysourced alluvial fans and a far-sourced wider fluvial system, and ii) the control exerted by tectonics on the stratigraphic architecture. Initially, uplift resulting from folding and thrusting in the Sierras Marginales precluded the entrance through this area into the Ebro basin of a wide fluvial system sourced in internal zones of the Pyrenean chain (including the Axial Zone). A subsiding area was created in the southern front of the Sierras where west-flowing alluvial fans generated, having their source areas in the rejuvenated reliefs. The subsequent cessation of movement of the tectonic structures permitted these reliefs to be subdued and the overpassing of the north-coming fluvial system that progressively covered a wider area. Sequential evolution and stratigraphic architecture evidence thrust emplacement geometry and chronology, including out-of-sequence reactivation of structures and the influence of evaporite flow along the décollement. Although these syn-tectonic deposits belong to the Ebro basin succession, its megasequential evolution differs from the general sequence established for the basin fill, highlighting the importance of differentiating the influence of near-coming sedimentary systems when interpreting basin-scale sequence stratigraphy

Caracterización estratigráfica de las megacapas 3, 5 y 8 del Grupo de Hecho del sector de Villanúa (Huesca)

Las megacapas eocenas en la Cuenca de Jaca (Pirineos) son capas cartografiables que representan eventos catastróficos. Estas capas se pueden observar y mapear en grandes longitudes, lo que permite su estudio en diferentes afloramientos. De esta forma, es posible estudiar su heterogeneidad, tanto lateral como vertical. Este trabajo se basa en el estudio de las megacapas 3, 5 y 8 del Grupo Hecho, en los alrededores de Villanúa (Huesca, Pirineo Aragonés) y sus principales características, con el objetivo de conocer los cambios que presentan en los diferentes afloramientos y así poder planificar cualquier acción en relación con estas capas.<br /

Ecological characterization of Holocene ostracods of Ojos de Añavieja springs (Soria, Spain)

In this work, the holocene ostracod assemblages of the Añavieja surrounding springs have been studied for the first time, allowing the preliminary differentiation of three subenvironments within this wetland. Thus, the first identified subenvironment gathers areas with high ecological stress due to the seasonality of the water flow and the possible anthropic contamination, where Eucypris virens abounds. The predominance of Cypria ophtalmica defines a second environment, being characterised by the development of large vegetation covers in three of the studied springs. In the third subenvironment the abundance of D arwinula stevensoni and the high water temperature (18.5 ºC) suggest a thermal origin for the spring of Añavieja. This work highlights the use of these microorganisms to characterise ecologically this wetland and to detect possible anthropic impacts on it. The definition of these recent assemblages and their ecological variables allow the comparison with fossil assemblages, thus providing the realization of accurate palaeoenvironmental reconstructions in this areaEn este trabajo se han estudiado, por vez primera, las asociaciones holocenas de ostrácodos de las surgencias de agua del entorno de Añavieja (Soria), que han permitido diferenciar, de manera preliminar, tres subambientes dentro de este humedal. Así, se identifica un primer subambiente que agrupa zonas con un alto estrés ecológico, debido a la estacionalidad del flujo hídrico y la posible contaminación antrópica, donde abunda Eucypris virens. El predominio de Cypria ophtalmica define un segundo subambiente, caracterizado por el desarrollo de amplias coberteras vegetales en tres de las surgencias estudiadas. En el tercer subambiente, la abundancia de Darwinula stevensoni y la elevada temperatura del agua del manantial de Añavieja (18,5 ºC) sugieren una naturaleza termal para el mismo. Con este estudio se pone de manifiesto la utilidad de estos microorganismos para caracterizar ecológicamente este humedal y detectar posibles afecciones antrópicas en el mismo. La definición de estas asociaciones actuales y sus variables ecológicas permitirá compararlas con las asociaciones fósiles, facilitando así la realización de reconstrucciones paleoambientales precisas en esta áre

New finding of proboscidean remains in fluvial deposits affected by karstification. Early Pleistocene. Ebro Basin, Zuera (Zaragoza)

A partial tusk of Elephantidae indet. was recently discovered in Early Pleistocene gravel deposits belonging to a terrace of the Gállego River, near to Zuera village. Stratigraphic studies have allowed four sedimentary units to be differentiated, named (from base to top) U1 to U4. The whole succession is 35 m thick; the tusk remains were collected at the top of unit U1. Preliminary report on the taphonomy suggests that this specimen could be a reworked fossil. Evaporite dissolution related with karst processes caused deformation structures in the overlying Quaternary deposits. Synform and tubular shapes (delimited by faults) were generated. Karstification favoured the preservation of the fossil remainsSe da a conocer el hallazgo de una defensa incompleta de Elephantidae indet. en depósitos de gravas correspondientes a una terraza del río Gállego, próxima a la localidad de Zuera, de edad Pleistoceno inferior tardío. Los estudios estratigráficos realizados han permitido definir cuatro unidades denominadas de base a techo como U1 a U4 que en conjunto integran una sucesión de unos 35 m de espesor, situándose la defensa a techo de la unidad U1. El análisis tafonómico preliminar parece indicar que se trataría de un fósil reelaborado. Los depósitos se encuentran afectados por procesos kársticos en evaporitas que han dado lugar a estructuras de deformación con geometría sinforme laxa o tubular (delimitada por fallas). La existencia de estos procesos kársticos ha favorecido la conservación del resto fósil encontrad

An exceptional paleoichnological record of artiodactyls in the early Oligocene of Abiego (Huesca, Spain)

RESUMEN: El yacimiento de Fondota en Abiego (Huesca, España) es uno de los yacimientos de icnitas de mamíferos más relevantes en el Paleógeno europeo por presentar un número excepcional (más de 600 icnitas) de artiodáctilo. Se localiza en la Cuenca del Ebro, en la base de la Formación Peraltilla (Oligoceno inferior) en un nivel de calizas lacustres. Las icnitas poseen una gran variabilidad en sus morfologías y grado de conservación, sin embargo en la mayoría se observa la impresión de dos dedos en posición anterior, siendo este carácter típico de mamíferos artiodáctilos. Se han identificado cuatro morfotipos: dos se relacionan con el icnogénero Anoplotheriipus; un tercero con Entelondontipus cf. viai; y el cuarto son icnitas indeterminadas de gran tamaño. El yacimiento posee además 32 rastros del icnogénero Anoplotheriipus, que han permitido determinar un posible comportamiento gregario de sus productores.RESUMO: A jazida de Fondota em Abiego (Huesca, Espanha) é uma das jazidas de ichnitas de mamíferos mais importantes no Paleogénico Europeu por apresentar um número excecional (mais de 600 ichnitas) de artiodáctilo. Esta jazida localiza-se na Bacia do Ebro, na base da Formação Peraltilla (Oligocénico inferior) num nível de calcários lacustres. As ichnitas possuem uma grande variabilidade nas suas morfologias e grau de conservação, contudo, na maioria observa-se a impressão de dois dedos posicionados anteriormente, característica típica dos mamíferos artiodáctilos. Foram identificados quatro morfotipos: dois relacionados com o icnogénero Anoplotheriipus; um terceiro com Entelondontipus cf. viai; e o quarto são ichnitas indeterminadas de grande tamanho. A jazida possui ainda 32 rastos do icnogénero Anoplotheriipus, que permitiram determinar um possível comportamento gregário dos seus produtores.ABSTRACT: The Fondota tracksite in Abiego (Huesca, Spain) is one of the most relevant in the Paleogene of Europe, due the exceptional number of artiodactyl ichnites (more than 600). It is located in the Ebro Basin in the base of the Peraltilla Formation (Early Oligocene) and is preserved in a lacustrine limestone bed. The ichnites have great variability both in their morphologies and degree of morphological preservation. However, all of them present the impression of two digits in an anterior position, a feature typical of artiodactyl footprints. Four morphotypes been identified: two of them related to the ichnogenus Anoplotheriipus, a third related to Entelondontipus cf. viai; and a fourth indeterminate morphotype compound of large-sized ichnites. The site also has 32 trackways of the ichnogenus Anoplotheriipus, which have made it possible to determine their possible gregarious behavior.info:eu-repo/semantics/publishedVersio

Gamificando la visión geológica sobre el cambio climático en las Olimpiadas de Geología

En este trabajo se presenta una secuencia didáctica donde el alumnado analiza e interpreta datos con el objetivo de construir explicaciones científicas en un contexto de gamificación. Se utilizan las variaciones climáticas del pasado como eje central de la secuencia aprovechando la gran repercusión mediática que tiene el problema del cambio climático y, por tanto, el interés que suscita entre los estudiantes. Los resultados muestran que el alumnado utiliza los datos que aporta la Geología en el conocimiento de los contextos climáticos en el pasado