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

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 /

Estudio estructural y sedimentario de un sector de los Puertos de Beceite (Teruel)

This work presents a study about the structure and the relationships between tectonics and sedimentation in the area of Beceite during the Alpine Orogeny. This area is located in the linking zone between the Iberian Chain and the Coastal Catalan Chain. In this geological context, the area is important because it combines the structural style of the Iberian Chain and the structural trend of the Coastal Catalan Chain. This work provides new data that allow improving our knowledge on the evolution of the Alpine Orogeny in the Iberian Plate. The sedimentology section is focused on the study of different Cenozoic tectono-sedimentary units and, particularly, the sedimentary characteristics of the Peña Galera alluvial fan. The structural section includes description and analysis of geometry of macrostructures, kinematics and paleostresses. At a macrostructural scale, the study is based on the elaboration and interpretation of the geological map and two geological cross sections, one of them in detail within the area or Peña Galera. At a microstructural scale, kinematical data been obtained for interpreting transport directions of thrusts. The paleostress analysis is based on the orientation of solution lineations in conglomerate pebbles, which were collected in 11 data sites through the Cenozoic series. During the Alpine Orogeny, three intraplate compressional stress fields were recorded in the Beceite area, with compression directions ENE-OSO, NNE-SSO y NNO-SSE. These compression directions match the main regional stress fields recognized within the Iberian Chain. Finally, it has been possible to propose a structural and sedimentary evolution model during the Alpine Orogeny

Estructura del flanco occidental del anticlinal de Boltaña. Relaciones tectónica-sedimentación.

Estudio de la estructura del sector central del flanco occidental del anticlinal de boltaña, y los depósitos del Grupo Hecho que se encuentran en él. Se realiza una cartografía y un corte, además de un estudio estratigráfico de estas capas y su relación con el pliegue

Paleobiología e interpretación paleoambiental del yacimiento de icnitas de La Sagarreta (Paleógeno, Peralta de la Sal, Huesca)

En el siguiente trabajo se recoge el estudio de un nuevo yacimiento de icnitas de La Sagarreta. Este yacimiento se encuentra en la Fm. Peralta, la cual se ha datado como perteneciente al Oligoceno inferior, se ha interpretado tradicionalmente como depósitos de un abanico aluvial. Sin embargo la serie en la que se encuentra el yacimiento se ha interpretado como un delta situado en la zona marginal de un gran lago salino en cuya superficie se encontraban los productores. En este yacimiento se encuentran icnitas de perisodactyla, asociadas al icnogénero Plagiolophustipus montfalcoensis, icnitas de artiodactyla, dividido en dos icnotaxones según su morfología y dimensiones asociándose a Megapecoripeda velox y Entelodontipus cf. viai, icnitas de carnivora denominadas como Canipeda isp. y las mas dominantes las icnitas de aves, las cuales se han dividido en dos según posean o no en hallux. Las icnitas avianas con hallux se han asociado a la morfofamilia Gruipedidae mientras que las icnitas sin hallux se relacionan con la morfofamilia Avipedidae. <br /

Nuevas aportaciones sobre la estructura de la terminación occidental del anticlinal Barbastro-Balaguer

En este trabajo se presenta el estudio estructural de la terminación occidental del anticlinal de Barbastro-Balaguer. Con base en una síntesis cartográfica, nuevos datos estructurales, la interpretación de perfiles de sísmica de reflexión y la reinterpretación parcial de varios sondeos profundos de la zona, se han elaborado dos cortes geológicos. Éstos, más un tercer corte de autores previos, permiten describir la estructura de la terminación occidental del anticlinal en tres sectores distintos. En el sector oriental, o de Calasanz, el anticlinal se desdobla en dos ramas, individualizando un sinclinal laxo entre ambas. En el sector central, o del Cinca, el flanco sur del anticlinal lo componen los materiales autóctonos de la Cuenca del Ebro y el flanco norte, la lámina basal de las Sierras Marginales se dispone sobre los yesos de la Fm. Barbastro y sus equivalentes terrígenos laterales. En el sector occidental, o de Bierge, un retrocabalgamiento enraizado en la Fm. Barbastro caracteriza la estructura. A pesar del control estructural, ciertas interpretaciones de la geología en profundidad tendrán que precisarse mediante la aplicación futura de técnicas geofísicas. In this work we present a structural study of the western end of the Barbastro-Balaguer anticline. We elaborated two new cross sections based on a geological map synthesis, new structural data, seismic reflection profiles interpretation and the reinterpretation of well log data. These two cross sections together with an already published one allow to describe the subsurface structure in three different sectors. In the eastern or Calasanz sector, the anticline splays into two branches that individualize a gentle syncline in between. In the central or Cinca sector, the southern flank is composed by Ebro Basin deposits whereas in the northern flank the basal Sierras Marginales thrust sheet lies onto the equivalent terrigenous facies of the Barbastro Fm. In the western or Bierge sector a backthrust rooted on the Barbastro Fm. characterizes the structure. Despite the proper structural control, several interpretations of the subsurface geology can be further constrained by means of the application of different techniques

Análisis de la ciclicidad del registro sedimentario de edad Pleistoceno Superior del humedal de Valdegeña (Soria, NE de España).

El testigo del sondeo Villar evidencia que en la cabecera del río Rituerto (Soria) existió durante el Pleistoceno Superior un sistema aluvial progradante con áreas palustres. El análisis espectral de los valores de susceptibilidad magnética medidos sobre el testigo pone de manifiesto la existencia de dos ciclos periódicos (5,8 y 20,3 m) muy bien definidos en los 50 metros superiores. Basándonos en la datación de los materiales (14C AMS y OSL) los primeros pueden corresponder a las oscilaciones Dansgaard-Oeschger y los segundos a los ciclos de Bond, localizados entre eventos Heinrich. La correlación con los valores ded18O del sondeo GISP2 permite proponer que en las etapas más frías se depositaron facies más groseras, con los valores más bajos de susceptibilidad magnética. En las etapas más cálidas (interestadiales de los ciclos Dansgaard-Oeschger) se depositaron facies más finas y con valores más altos de susceptibilidad que atribuimos a la neoformación de minerales magnéticos en suelos desarrollados de forma estable. The main features of the Villar core evidence that in the headwater area of Rituerto River (Soria) an alluvial plain with palustrine areas developed during the Late Pleistocene, which prograded along time. The spectral analysis of the magnetic susceptibility values measured on the core evidence two periodic cycles (5.8 and 20.3 m-thick), very well defined in the uppermost 50 meters. Based on 14C AMS and OSL dating is considered that the former (5.8 cycle) may correspond to the Dansgaard-Oeschger oscillations and the later (20.3 cycle) to the Bond cycles between Heinrich events. The correlation with thed18O values of the GISP2 core permits to propose that during the coldest stages coarser facies deposited, showing the lowest values of magnetic susceptibility. During the warmest stages (interstadials of Dansgaard-Oeschger cycles) finer facies with higher susceptibility values deposited.We consider this high values are related to magnetic minerals neoformated in soils, which during warmer periods were more stable

Mapa de asociaciones de facies Neógenas del sector norte de la Cuenca de Teruel

El relleno sedimentario mioceno superior-cuaternario del sector norte de la Cuenca de Teruel se caracteriza por asociaciones de facies referibles a abanicos aluviales, medios lacustres, palustres y, menos frecuentes, eólicos y deltaicos. La cartografía de dichas asociaciones de facies y de las estructuras tectónicas muestra una configuración propia de cuencas extensionales asimétricas. Los abanicos aluviales, principalmente procedentes de los márgenes oriental y occidental de la cuenca, presentaban diferentes dimensiones, siendo de mayor extensión los del margen occidental, tectónicamente inactivo durante el depósito de la serie estudiada. Los abanicos aluviales conectaban con lagos poco profundos situados en áreas centrales pero más próximas al margen activo. El espacio de acomodación generado por fallas sinsedimentarias intracuencales favoreció la preservación de asociaciones de facies eólicas y deltaicas, poco frecuentes en este tipo de cuencas continentales. The Upper Miocene-Quaternary sedimentary fill of the northern sector of the Teruel Basin is characterized by facies associations corresponding to alluvial fans, lakes and palustrine areas, as well as less common aeolian and deltaic environments. The map of facies associations corresponding to different sedimentary environments, and tectonic structures, reveals asymmetrical fill architecture. Alluvial fans were mainly sourced from the eastern (tectonically active) and western (passive) basin margins, connected downstream with shallow carbonate or evaporite lakes located in central basinal areas but closer to the active margin. The accommodation space created by synsedimentary intrabasinal faults enabled preservation of aeolian and deltaic associations, not very common in this type of basins

Response of alluvial systems to Late Pleistocene climate changes recorded by environmental magnetism in the Añavieja Basin (Iberian Range, NE Spain)

Environmental magnetic proxies were analyzed in a relatively monotonous, ~25.3m thick alluvial sedimentary sequence drilled in the Añavieja Basin (NE Spain). Results from the core AÑ2 suggest that the concentrationdependent magnetic parameters mainly reflect variations in the content of detrital magnetite, sourced in the catchment rocks and soils of the basin, via changes in the dynamics of alluvial fans due to temperature changes in the northern hemisphere during the Late Pleistocene. The correspondence between the magnetic proxies and the temperature variations in the North Atlantic region (NGRIP curve) indicates that higher (lower) concentrations and finer (coarser) magnetite grains coincide with warm (cold) periods. We propose that during cold periods, a sparser vegetation cover favored the incoming of higher energy runoff bearing coarser sediments to the basin that are relatively impoverished in magnetite. In contrast, during warm periods, the wider distribution of the vegetation cover associated with the lower runoff energy lead to finer, magnetite-richer sediment input to the basin. Maghemite, presumably of pedogenic origin, appears to be present also in the studied alluvial sediments. Further studies are necessary to unravel its palaeoclimatic significance