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The evolution of the fluvial and alluvial Quaternary deposits in the surroundings of Zaragoza is controlled by the dissolution of the Miocene substratum . Karstification of Miocene evaporites conditioned changes in thickness and sedimentary facies of such deposits , and, in addition, the land forms resulting from its degradation. Recently created new road and railway cuts expose, not only unconformable Quaternary remains, but also disorganized materials in ancient dolines. These increase in thickness may be the reason for the preservation of Quaternary remains in the hills, forming "inverted reliefs", En el entorno de Zaragoza la evolución de los depósitos cuaternarios (fluviales y aluviales) está muy influida por el comportamiento del substrato mioceno. La karstificación de dicho substrato ha condicionado los espesores y las facies sedimentarias en terrazas y glacis, así como las formas del relieve que resultan de la degradación de estos depósitos. Las nuevas obras lineales han creado cortes donde se observa que algunos cerros están coronados por restos de materiales cuaternarios disconformes y también por rellenos desestructurados de material colapsado en dolinas. Dichos rellenos han prolongado la supervivencia de los cerros dando lugar a relieves invertidos

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 remains, Se 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 encontrado

En este trabajo se realiza el estudio paleomagnético preliminar del nivel de terraza más antiguo (198-220 m) del río Ebro, en el sector central de la Cuenca del Ebro. Igualmente se ha realizado un análisis conjunto de la anisotropía de susceptibilidad magnética (AMS) y los datos de paleocorrientes en la zona. Las desmagnetizaciones muestran direcciones con una clara polaridad inversa de alta temperatura (300-675°C), con una componente adicional normal viscosa, In this work we carry out a preliminary paleomagnetic analysis focused in the oldest fluvial terrace (198-220 m) of the Ebro River, in the central sector of the Ebro Basin. We have also conducted a combined analysis of anisotropy of magnetic susceptibility (ASM) and paleocurrent data in the area. The paleomagnetic record shows a clear high temperature (300-675° C) reverse polarity with an additional viscous normal component 773.000 years. The ASM shows a more complex behaviour controlled by the magnetic mineralogy. Dominant paramagnetic fabrics show magnetic foliation parallel to the bedding indicating their potential utility in the study of paleocurrents

En este trabajo se describen y caracterizan diversos ejemplos de formas kársticas y depósitos asociados en el nivel de terraza T3 del río Ebro. El estudio se ha llevado a cabo desde una perspectiva multidisciplinar (geomorfológica, sedimentológica, estructural y geofísica). Se describen tres ejemplos de paleodolinas, (alguna de ellas sinsedimentarias) generadas dentro de un sistema fluvial trenzado, atendiendo a su morfología y características internas y se deduce para cada una la relación entre el momento de depósito de los materiales afectados y el fenómeno de disolución kárstica. Las direcciones de fractura en las paleodolinas y su entorno, indican un posible condicionante estructural de la fracturación del substrato evaporítico en su formación. Además la prospección con georradar ha permitido caracterizar en profundidad diferentes morfologías kársticas y estimar la posición del substrato evaporítico, In this work several examples of karst morphologies and their associated deposits in the T3 terrace level of the Ebro River are described and characterized. The study was carried out from a multiproxy approach (geomorphological, sedimentological, structural and geophysical). Three examples of palaeodolines (some of them synsedimentary) generated within a braided fluvial system, are described and interpreted according to their morphology and internal characteristics. Moreover a temporal relationship between the time of deposition of the deformed materials and the karstic dissolution process is proposed. The similarity of fracture trends in Neogene and Quaternary materials points to a possible structural conditioning for doline genesis. Moreover GPR profiles have permitted to identify karst morphologies in the subsoil and estimate the position of the Neogene rocks

En este trabajo se describen y caracterizan diversos ejemplos de formas kársticas y depósitos asociados en el nivel de terraza T3 del río Ebro. El estudio se ha llevado a cabo desde una perspectiva multidisciplinar (geomorfológica, sedimentológica, estructural y geofísica). Se describen tres ejemplos de paleodolinas, (alguna de ellas sinsedimentarias) generadas dentro de un sistema fluvial trenzado, atendiendo a su morfología y características internas y se deduce para cada una la relación entre el momento de depósito de los materiales afectados y el fenómeno de disolución kárstica. Las direcciones de fractura en las paleodolinas y su entorno, indican un posible condicionante estructural de la fracturación del substrato evaporítico en su formación. Además la prospección con georradar ha permitido caracterizar en profundidad diferentes morfologías kársticas y estimar la posición del substrato evaporítico In this work several examples of karst morphologies and their associated deposits in the T3 terrace level of the Ebro River are described and characterized. The study was carried out from a multiproxy approach (geomorphological, sedimentological, structural and geophysical). Three examples of palaeodolines (some of them synsedimentary) generated within a braided fluvial system, are described and interpreted according to their morphology and internal characteristics. Moreover a temporal relationship between the time of deposition of the deformed materials and the karstic dissolution process is proposed. The similarity of fracture trends in Neogene and Quaternary materials points to a possible structural conditioning for doline genesis. Moreover GPR profiles have permitted to identify karst morphologies in the subsoil and estimate the position of the Neogene rocks

En este trabajo se describe e interpreta una unidad detrítica (gravas, arenas y escasas lutitas) intercalada entre gravas fluviales desarrolladas en sistemas entrelazados, caracterizada por la presencia de estratificación cruzada de gran escala. La sucesión estudiada, localizada en la zona central de la Cuenca del Ebro, recubre evaporitas Neógenas. El análisis sedimentológico, completado mediante estudios de georradar que revela la distribución y geometría de formas kársticas en el subsuelo, permite interpretar la unidad de estratificación cruzada como resultado de la progradación de un delta en un lago cuya génesis estuvo relacionada con procesos de karstificación y desarrollo de dolinas durante el Pleistoceno, In this work a detrital (gravels, sands and minor lutites) unit characterised by high scale cross-strata enclosed in Pleistocene braided fluvial gravels is described and interpreted. The studied succession, located in the central area of the Ebro Basin, overly Neogene evaporites. Sedimentological analysis supported by georadar survey, that reveal spatial distribution and geometry of karst forms in the subsoil, allow to interpret the cross-strata unit as a result of delta progradation into a lake whose genesis was related with karstification processes and doline development during the Pleistocen

The relative role ofextensional tectonics and erosional lowering in the evolution of the Jiloca depression has been debated. The classic notion of a Pliocene, NNW-SSE trending graben is discussed by a number of authors; they enhance the role of differential erosion, based on the supposed identification of either numerous nested Paleogene-Early Miocene pediplains, or suballuvial Plio-Quaternary karstic surfaces. Nevertheless, the geometry of the sedimentary infilling (up to 100 m thick, controlled by the NW-SE master faults) and the evidence of tectonic offset at the Calamocha and Concud faults (160-180 m and 250 m, respectively) supports its tectonic origin

The study of the detrital sediments in the Ebro river terraces near Zaragoza has demonstrated that in this area karst is not only an active phenomenon at present but also during the Pleistocene. The Ebro River system had mainly braided features related to a general high water availability and was affected by the development ofdolines. The ana/ys/s ofdolines filling shows synsedimentary deformation linked to dissolution processes but probably also to tectonics. The preliminary mineralógica! study reveals the existence of some differences depending on the terrace age and also its own potential in palaeoenvironmental and source area studies

The study of the detrital sediments in the Ebro river terraces near Zaragoza has demonstrated that in this area karst is not only an active phenomenon at present but also during the Pleistocene. The Ebro River system had mainly braided features related to a general high water availability and was affected by the development ofdolines. The ana/ys/s ofdolines filling shows synsedimentary deformation linked to dissolution processes but probably also to tectonics. The preliminary mineralógica! study reveals the existence of some differences depending on the terrace age and also its own potential in palaeoenvironmental and source area studies

The relative role ofextensional tectonics and erosional lowering in the evolution of the Jiloca depression has been debated. The classic notion of a Pliocene, NNW-SSE trending graben is discussed by a number of authors; they enhance the role of differential erosion, based on the supposed identification of either numerous nested Paleogene-Early Miocene pediplains, or suballuvial Plio-Quaternary karstic surfaces. Nevertheless, the geometry of the sedimentary infilling (up to 100 m thick, controlled by the NW-SE master faults) and the evidence of tectonic offset at the Calamocha and Concud faults (160-180 m and 250 m, respectively) supports its tectonic origin

The Concud fault is a 13-km long fault located at the eastern boundary of the Jiloca graben (Teruel, Spain) that has been active during most of Late Pliocene and Quaternary times. Offsets measured in some dated stratigraphic levels (3.6 Ma, Ruscinian lacustrine carbonates, displacement = 250 m; 116-169 ka, Middle Pleistocene fluvial terrace, displacement = 39-68 m) allow to calculate the corresponding mean slip rates since those ages: 0.07 and 0.23-0.58 mm/year, respectively. No paleoseismic study has been yet carried out in this area. Nevertheless, through empirical correlation within fault data bases, the fault length and the calculated slip rate allow us to approach the recurrence period (1.3 to 16.2 ka) and the coseismic displacement (0.8 to 1.1 m). These non-directly inferred parameters are compared with observations at an outcrop close to Teruel where deposits of the lower fluvial terrace are offset 2 m, which could represent the latest displacement event(s) in the fault

The Concud fault is a 13-km long fault located at the eastern boundary of the Jiloca graben (Teruel, Spain) that has been active during most of Late Pliocene and Quaternary times. Offsets measured in some dated stratigraphic levels (3.6 Ma, Ruscinian lacustrine carbonates, displacement = 250 m; 116-169 ka, Middle Pleistocene fluvial terrace, displacement = 39-68 m) allow to calculate the corresponding mean slip rates since those ages: 0.07 and 0.23-0.58 mm/year, respectively. No paleoseismic study has been yet carried out in this area. Nevertheless, through empirical correlation within fault data bases, the fault length and the calculated slip rate allow us to approach the recurrence period (1.3 to 16.2 ka) and the coseismic displacement (0.8 to 1.1 m). These non-directly inferred parameters are compared with observations at an outcrop close to Teruel where deposits of the lower fluvial terrace are offset 2 m, which could represent the latest displacement event(s) in the fault

FrOm.the study of satellite imagery, up to 1.396 lineaments on Neogene rocks of the northeastern Duero Basin have been identified. Length of lineaments fluctuates from 137 to 19.818 m. The statistical analysis of lineament directions shows a NE-SW mode and N130, N020, N090-100 y N180 relative maxima. The study of lineament orientation pattern within specific length-intervals shows a NE-SW dominant trend for the 0-3.000 m interval and NW-SE dominant directions for lineaments largest than 3.000 m. The comparison between satellite lineaments and the main structures affecting the pre-Neogene basement indicates that the orientation of largest lineaments seems to be controlled by major previous structures. Minor lineaments can correspond to faults and joints newly formed under the regional stress field in the Duero Basin during the Neogene

The analysis of Landsat lineaments at the eastern end of the Aragonian Branch (comprising the palaeozoic core of the Montalban anticline, the Tertiary Montalban basin and several outcrops of Mesozoic rocks) shows a constant NE-SW direction maximum throughout the area, with a secondary NW-SE maximum. The lineament pattern remains unchanged when analysing separately lineaments in rocks of different ages (Paleozoic, Mesozoic, Paleogene, Neogene). The maximum density estimated from cumulative length of lines is 2 km per km2. The comparison with geological maps and field observations allow to interpret lineaments as fractures and faults, many of them with little or no offset. The main NE-SW trend seems to correspond to Late Variscan faults reactivated during the mesozoic as extensional faults at the Mesozoic basins North and South of the studied area. The NW-SE maximum coincides with the main structural trend of the Aragonian Branch. Lineaments trending N-S to NNW-SSE are scarce and limited to the surroundings of the Alpeh6s fault

FrOm.the study of satellite imagery, up to 1.396 lineaments on Neogene rocks of the northeastern Duero Basin have been identified. Length of lineaments fluctuates from 137 to 19.818 m. The statistical analysis of lineament directions shows a NE-SW mode and N130, N020, N090-100 y N180 relative maxima. The study of lineament orientation pattern within specific length-intervals shows a NE-SW dominant trend for the 0-3.000 m interval and NW-SE dominant directions for lineaments largest than 3.000 m. The comparison between satellite lineaments and the main structures affecting the pre-Neogene basement indicates that the orientation of largest lineaments seems to be controlled by major previous structures. Minor lineaments can correspond to faults and joints newly formed under the regional stress field in the Duero Basin during the Neogene

The analysis of Landsat lineaments at the eastern end of the Aragonian Branch (comprising the palaeozoic core of the Montalban anticline, the Tertiary Montalban basin and several outcrops of Mesozoic rocks) shows a constant NE-SW direction maximum throughout the area, with a secondary NW-SE maximum. The lineament pattern remains unchanged when analysing separately lineaments in rocks of different ages (Paleozoic, Mesozoic, Paleogene, Neogene). The maximum density estimated from cumulative length of lines is 2 km per km2. The comparison with geological maps and field observations allow to interpret lineaments as fractures and faults, many of them with little or no offset. The main NE-SW trend seems to correspond to Late Variscan faults reactivated during the mesozoic as extensional faults at the Mesozoic basins North and South of the studied area. The NW-SE maximum coincides with the main structural trend of the Aragonian Branch. Lineaments trending N-S to NNW-SSE are scarce and limited to the surroundings of the Alpeh6s fault