20 results on '"Tortosa, Francisco"'
Search Results
2. Tectonic geomorphology of an active slow-moving, intrabasinal fault: The Galera Fault (Guadix-Baza Basin, central Betic Cordillera, southern Spain)
- Author
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Medina-Cascales, Iván, García-Tortosa, Francisco J., Martin-Rojas, Iván, Pérez-Peña, José Vicente, and Alfaro, Pedro
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- 2021
- Full Text
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3. Nest switching and alloparental care in colonial white storks
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Redondo, Tomas, Tortosa, Francisco, and De Reyna, Luis Arias
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Storks -- Research ,Birds -- Eggs and nests ,Parental behavior in animals -- Observations ,Zoology and wildlife conservation - Abstract
The alloparental care and nest switching is observed in white storks, Ciconia ciconia. Alloparental care is the nest switching by young birds for full adoption by foster parents. Nest switching is due to decrease in feeding rates by the parents and an increase in flight exercises of nestmates. Residential chicks suffer lower feeding rates during adoption. The chicks reach their nutritional independence in foster broods. Nest switching was observed in 40% of broods.
- Published
- 1995
4. Présence du complexe tectonique Malaguide à l'est de Carthagène (zone interne Bétique, Espagne)
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García Tortosa, Francisco Juan, López-Garrido, Angel Carlos, and Sanz de Galdeano, Carlos
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- 2000
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5. Herbaceous cover enhances the squamate reptile community in woody crops.
- Author
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Carpio, Antonio J., Castro, Jesús, Mingo, Valentin, and Tortosa, Francisco S.
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HERBACEOUS plants ,SQUAMATA ,REPTILE ecology ,AGRICULTURAL intensification ,GROUND cover plants ,SPECIES diversity - Abstract
The intensification of agriculture entails the simplification and homogenisation of the landscape, which has serious negative impacts on animal biodiversity. Herbaceous ground cover in olive groves creates heterogeneous patchworks that differ as regards how intensively farmed olive groves are structured and composed, which may lead to a decrease in this loss of biodiversity. Reptiles rapidly respond to changes in vegetation and other habitat disturbances, in spite of which, this taxa has received very little attention with regard to their vulnerability to agriculture systems. In this study, we investigated the response of a squamate reptile assemblage to different management systems in olive groves. Reptile communities were recorded in areas with three types of olive grove management systems: bare ground, natural cover crop, and monospecific cover crop. We further compared habitat structure and vegetation richness in the study area in order to verify if management systems have an impact on the frequency of occurrence and diversity of squamate reptiles species within olive groves. The community composition of reptiles differed among the three management systems, although this was modulated by the age of the olive trees. Our results show that the squamate reptile communities were more restricted in areas of intense management (bare ground) than in those with cover crops. When herbaceous covers existed, natural ground cover harboured a more diverse community. Our data suggest that while monospecific cover crops improve the frequency of occurrence of reptiles, species richness does not increase; however, more heterogeneous herbaceous ground cover (which, for instance, contain more species and are more similar to natural vegetation) would be a better solution regarding the promotion of diversity in reptile assemblages in agricultural landscapes. Finally our results may be used to improve the habitat quality of squamate reptile communities in similar woody crops like vineyards or orchards, where cover crops are beginning to be implemented. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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6. Segmental absence of intestinal musculature concerning a child with acute appendicitis.
- Author
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Pereira, Stéfanie, Tortosa, Francisco, and Gonçalves, Miroslava
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APPENDICITIS diagnosis ,PERITONITIS ,SURGICAL complications ,THERAPEUTICS - Abstract
Segmental absence of intestinal musculature (SAIM) is a rare histopathologic entity with few described cases, most of which in neonates. Rare reports of pediatric cases have been made. Pathogenesis is still uncertain. This report aims to highlight a pathologic condition that substantially affects the clinical evolution of an abdominal post-operative state as well as the therapeutic approach. We present the case of a 4-year old child, previously healthy, with a 4-day long intestinal obstruction. The exploratory laparotomy demonstrated peritonitis from a necrosed and perforated acute appendicitis. Post-operatory intestinal perforation led to a second laparotomy, with resection of a perforated ileal segment and one with vascular compromise. Pathologic analysis showed segmental absence of intestinal musculature of the small bowel. On a third operative time, resection of the macroscopically injured bowel segments and high protective enterostomy were made. A three years follow-up shows a healthy, well-developed child, who has already undergone enterostomy closure with no intercurrences. Etiology remains to be defined, possibly related to congenital or ischemic acquired defects. It usually manifests in neonates, but we present a case of a 4-year old child. Treatment consists of resection of the injured bowel segments. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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- View/download PDF
7. Restocking a keystone species in a biodiversity hotspot: Recovering the European rabbit on a landscape scale.
- Author
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Guerrero-Casado, José, Carpio, Antonio J., Ruiz-Aizpurua, Leire, and Tortosa, Francisco S.
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EUROPEAN rabbit ,BIODIVERSITY ,WILDLIFE conservation ,ENDANGERED species ,RABBIT breeding ,HABITATS - Abstract
Abstract: Rabbit populations in Iberia remain at low densities in several areas in which their endangered predators still coexist, and the recovery of these populations is therefore urgent if the integrity of Iberian Mediterranean ecosystems is to be maintained. The enhancement of wild rabbit populations has been attempted through the use of in situ extensive rabbit captive breeding enclosures (restocking plots), which reduce mortality caused by terrestrial predators and dispersal movements and permit the breeding of young individuals which can then naturally disperse to settle in the surrounding areas. However, their effectiveness, the role of its size, the optimal habitat management that should be promoted around them and the habitat features remains uncertain. Here, we show results from a four year study of an ambitious rabbit restocking plan on a landscape scale. We measured rabbit abundance in a vast area in which thirty-two restocking plots were built to create an initial rabbit population for further dispersion, in addition to an intensive habitat management program. We also compared rabbit abundance between managed and unmanaged UTM cells of 2.5km×2.5km. Our results showed that rabbit abundance was three times higher in managed cells, but four years after restocking, rabbit abundances had only reached the threshold needed to support stable Iberian lynx presence (at least 10 latrines per km
−1 ) in 9 of the 23 managed cells. Rabbit abundance was strongly affected by habitat treatment and scrub coverage. The increase of shelter was useful in low cover areas but ineligible in places with high scrub cover, where the increase of refuge plus scrub clearing to create pastures improve rabbit abundance more effectively. In the light of our results, restocking plots should be built only in places with suitable habitat, whereas pastures should be created in dense scrublands and refuge in low cover areas. [Copyright &y& Elsevier]- Published
- 2013
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8. The effects of fasting and refeeding on biochemical parameters in the red-legged partridge (Alectoris rufa)
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Rodríguez, Pablo, Tortosa, Francisco S., and Villafuerte, Rafael
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PARTRIDGES , *PHASIANIDAE , *DIET in disease , *NATURAL foods - Abstract
Abstract: Every year, about three million farm-reared red-legged partridges are released in Spain for hunting purposes, most of them for restocking where the success is very low. Some factors such as the sudden shift from abundant commercial energy-rich diet to natural food and absence of experience at looking for natural food resources could cause a rapid physical deterioration, being more vulnerable to predation and disease. To determine fasting capacity in red-legged partridges, we fasted 32 birds during 4 days and then we refed them, collecting blood samples and body masses during the experiment. Red-legged partridges entered in the third critic phase of fasting, in which body proteins became the main energetic source, after 48 h of fasting. The fasting period caused an average loss of 17% of their initial body mass and only attained a 93.6% of their initial body mass after 24 days of refeeding. The limited capacity to resist fasting in the red-legged partridge could be one of the reasons for the low success in restocking, mainly in those where neither supplementary feeding nor acclimation period is allowed for birds before they are finally released. [Copyright &y& Elsevier]
- Published
- 2005
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9. STOMACH CANCER CASES IN AN INTERNAL MEDICINE UNIT AT A REFERENCE HOSPITAL, PORTUGAL: STATISTICAL REPORT
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Santo, Catarina Espírito, Tortosa, Francisco, Acabado, Alba, Cantiga, Paulo, and Nogueira, José Braz
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- 2011
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10. Natural and anthropogenic-induced stressors affecting the composition of fish communities on the rocky reefs of Ecuador.
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Figueroa-Pico, Juan, Tortosa, Francisco S., and Carpio, Antonio J.
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FISH communities ,CORAL colonies ,REEFS ,CORAL reef fishes ,TRANSECT method ,CORALS ,CORAL bleaching - Abstract
Natural and human-induced stressors have threatened the sustainability of the fish communities of coral-rocky reefs worldwide in the last decades. The composition of the fish communities on the reefs of Ecuador and the factors affecting spatiotemporal changes are unknown. We studied the influence of the descriptors of structural complexity, the current status of coral and human-induced variables over fish communities. A video transect method was used to assess fish communities in three zones (slope, crest, and bottom) of two reefs during two seasons (rainy and dry). The structure of fish communities was highly influenced by the zones and season; rugosity and live coral affected the fish composition on the crest and slope zones. The fractured coral and derelict fishing gear on coral produced an adverse effect on fish composition over the crest. A multifactorial process causing loss of structural complexity and affecting fish composition was identified, however, periodical assessment is required for a greater understanding of this process. Unlabelled Image • Differences in the fish composition between the study sites, zones and seasons. • High presence and prevalence of derelict fishing gear
. on the coral colonies on the crests. • Negative effects over fish composition in relation to derelict fishing gear and fractured coral. • Spatial and temporal changes in fish communities driven by a multifactorial degradation process. • Evidence of a possible major threat of habitat degradation to coral-dependent fish populations. [ABSTRACT FROM AUTHOR]- Published
- 2021
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11. Environmental challenges of intensive woody crops: The case of super high-density olive groves.
- Author
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Guerrero-Casado, José, Carpio, Antonio J., Tortosa, Francisco S., and Villanueva, Anastasio J.
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- 2021
- Full Text
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12. Clay saline diagenesis in lake Plio-Pleistocene sediments rich in organic matter from the Guadix-Baza Basin (Betic Cordillera, SE Spain).
- Author
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Jiménez-Millán, Juan, Abad, Isabel, García-Tortosa, Francisco Juan, Nieto, Fernando, and Jiménez-Espinosa, Rosario
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SALT lakes , *LAKE sediments , *ORGANIC compounds , *CLAY , *MIXING height (Atmospheric chemistry) , *PALYGORSKITE , *KAOLINITE - Abstract
This study presents a mineralogical analysis of the effect of hypersaline lake environments rich in organic matter on the mineral transformations in sediments of the eastern part of the Guadix-Baza Basin (Betic Cordillera). Dark sediments with fragments of organic matter are rich in phyllosilicates (K-white mica, illite-smectite mixed layers, –I/S– minor amounts of paragonite, palygorskite, chlorite and kaolinite) and contain quartz, feldspars, and framboidal pyrite. X-ray diffraction patterns of I/S (R0 type, disordered) revealed a continuous between the positions of pure smectite and 30% of illite layers. Chemical composition of I/S mixed layers indicated a significant beidellitic substitution of Si by AlIV, Fe + Mg > 1 atoms per formula unit (a.p.f.u.) and K content up to 0.42 a.p.f.u. These data suggested the presence of a minor and variable amount of illitic layers among the major smectitic ones. Saline waters of the lake and the reducing environment of the sediment favored Mg and Fe2+ uptake, generating octahedral negative charge, which together with the beidellitic substitution would provide clay layer negative charge enough to admit K incorporation in the interlayer, hence the beginning of a diagenetic low temperature illitization. • Hypersaline environments promoted low temperature diagenetic transformations. • Mg and Fe2+ uptake in smectites favored K incorporation in the interlayer. • Illite-smectite mixed layers indicate the beginning of a diagenetic illitization. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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13. Turbidity: A key factor in the estimation of fish species richness and abundance in the rocky reefs of Ecuador.
- Author
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Figueroa-Pico, Juan, Carpio, Antonio J., and Tortosa, Francisco S.
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SPECIES diversity , *CORAL reef ecology , *REEFS , *CORAL reefs & islands , *TURBIDITY , *REEF fishes , *CORAL communities - Abstract
• Differences in fish species richness and abundance depending on the sampling method. • Video-transect method was more efficient to assess the study variables. • Visibility significantly affected fish species richness and abundance. • Fish abundance was more affected by visibility in both sampling methods. • Visibility is a key factor for evaluating fish communities of rocky reefs. The effectiveness of using standardized sampling methods for fish communities in coral and rocky reefs has been widely discussed because it largely depends on the experience and skill of the observer, availability of high-definition equipment and the stability of local environmental parameters. The rocky reefs in Ecuador have highly variable conditions of turbidity, which can generate biases in the sampling of reef fish. The present work compares the effectiveness of detection of two sampling methods: 1) observer-band transects and 2) video-transects, as tools to determine the composition of fish communities in two rocky reefs subjected to high anthropic pressure and high variability in the conditions of turbidity. To achieve this goal, 48 transects of 100 m and variable-width on the dependence of turbidity conditions were performed in three geomorphological reef zones: the crest, slope, and bottom, where a community of fish was sampled from September 2017 to April 2018 using both methods. The results showed significant differences in the fish abundance recorded depending on the sampling method, the video-transect method was more efficient for the estimation of abundance. Comparison of the survey methods in reef zones showed that video-transects are more effective in detecting significant differences in abundance on the slopes of the reefs in comparison with observer-band transects. Turbidity significantly affected the abundance of fish detected by both sampling methods. Our results suggest that the video-transect method is more efficient to record fish abundance with respect to the observer-transect method under different conditions of turbidity. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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14. 3D geometry and architecture of a normal fault zone in poorly lithified sediments: A trench study on a strand of the Baza Fault, central Betic Cordillera, south Spain.
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Medina-Cascales, Iván, Koch, Leah, Cardozo, Néstor, Martin-Rojas, Iván, Alfaro, Pedro, and García-Tortosa, Francisco J.
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FAULT zones , *PLIOCENE Epoch , *ARCHITECTURE , *SEDIMENTS - Abstract
Abstract Successive excavation of 13 trenches of different orientations reveals the complexity of a normal fault zone in Pliocene-Pleistocene unconsolidated sediments on a strand of the Baza Fault, central Betic Cordillera, south Spain. These trenches and the excavation floor are interpreted and integrated to reconstruct the 3D geometry and internal architecture of the fault zone. The structure consists of two main fault strands: an eastern one with a few hundred metres throw and a western one with at least 15 m throw. These strands interact and gradually merge to the south, bounding a main deformation zone narrowing from ∼7 to 1 m along strike. Fault-bounded rock bodies, clay and sand smears, and clay injections define the structure. These features are highly variable in 3D. In the northern part of the outcrop, deformation is localized around the main strands, brittle in the west and more ductile to the east. As the strands and their fault zones increasingly interact, fault throw, rock deformation and maturity of the structure increase. Mechanical stratigraphy also controls the style of deformation. A realistic representation of this 4D picture of fault deformation is critical for modelling fluid flow in shallow to possibly deep, faulted sedimentary reservoirs. Highlights • A 3D trench study reveals the complexity of a normal fault zone in soft sediments. • Highly variable rock bodies, faults, smears and clay injections form the fault zone. • Variable fault geometries and throws cause a variable distribution of deformation. • Mechanical stratigraphy has a key role in the variability and style of deformation. • As main strands approach, fault throw, deformation and fault zone maturity increase. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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15. Does gender really matter? A structural equation model to explain risky and positive cycling behaviors.
- Author
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Useche, Sergio A., Montoro, Luis, Alonso, Francisco, and Tortosa, Francisco M.
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STRUCTURAL equation modeling , *BICYCLES , *PUBLIC health , *TRAFFIC safety , *EMPIRICAL research - Abstract
Introduction While the use of bicycles as mean of transport is growing worldwide, the increasing rates of traffic crashes involving cyclists have turned into a relevant scientific, public health, and road safety concern. According to several studies, and despite the fact that some countries are taking part in preventive actions, the data indicate that the problem of cycling injuries implies high costs for the community welfare, for the economy, and for healthcare systems, thus proving a clear need for solutions. In this regard, and considering the available empirical evidence, risky and positive riding behaviors have gained significant weight in terms of explaining, intervening in, and preventing traffic crashes of cyclists, and some evidence suggests that gender may influence the road behavior of users. Objective The objective of this study was to examine the effect of gender on cyclists' risky and positive riding behavior, considering a set of demographic, psychosocial and bike-use-related variables as potential predictors. Method For this cross-sectional study, data from 1064 cyclists (61.2% males and 38.8% females, aged between 17 and 80) from 20 countries, responding an electronic survey, were analyzed through a multi-group structural equation modeling approach. Results: Although hourly intensity, psychological distress and level of knowledge of traffic rules similarly predict the risky road behaviors of both genders, age and risk perception are significant behavioral predictors only in the case of male cyclists. On the other hand, positive behaviors of men are predicted by cycling intensity, knowledge of traffic rules and risk perception, while in the case of women psychological distress predicts -to a significant extent- positive behaviors. Age had no significant effect on the explanation of positive behaviors. Conclusion The findings of this study support the influence of gender in the statistical explanation of risky and protective behaviors, and they also reveal differentiating variables predicting the riding behavior of male and female cyclists. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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16. Evaluation of an unpalatable species (Anthemis arvensis L.) as an alternative cover crop in olive groves under high grazing pressure by rabbits.
- Author
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Carpio, Antonio J., Soriano, María-Auxiliadora, Guerrero-Casado, José, Prada, Laura M., Tortosa, Francisco S ., Lora, Ángel, and Gómez, José A.
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COVER crops , *OLIVE , *PLANTS for soil conservation , *EUROPEAN rabbit , *ANTHEMIS , *AGRICULTURE & the environment - Abstract
Sustainability is a key attribute for the future of the olive grove. Cover crops can be considered as an effective tool to achieve sustainability of olive orchards to reduce soil erosion, improve soil fertility and increase biodiversity. However, wild herbivores may forage on cover crops when natural food resources are scarce. In this study we assessed the impact of European rabbit grazing on the implantation of herbaceous cover crops of two native plant species, one palatable ( Bromus rubens L.) and the other unpalatable ( Anthemis arvensis L.) in two olive orchards with very scarce vegetation cover in Andalusia, Southern Spain. Eight rabbit exclusion plots, close to eight other unfenced plots, were planted where the aboveground biomass, height and the ground covered by each species were measured. The results showed that the biomass, height and the ground cover by B. rubens were higher in the rabbit exclusion areas (ground cover: 36.5 ± 3.3%; height: 30.3 ± 3.9 cm, averaged over the entire measuring period; and biomass: 158 ± 36 g/m 2 , in April) than in unfenced areas (ground cover: 1.9 ± 0.2%; height: 5.6 ± 0.7 cm; biomass: ≅0), while A. arvensis showed no difference in biomass, height or ground cover between the two treatments (ground cover: 11.3 ± 6.3%; height: 12.2 ± 7.9 cm, averaged over the entire measuring period; and biomass: 49.5 ± 10 g/m 2 , in April). The results further showed that the damage by rabbits was caused from the early stages of development of B. rubens , which avoid its growth; notwithstanding the plant biomass consumption was minimal, the damage caused was critical. These findings suggest that unpalatable species such as A. arvensis could be a suitable tool for establishing herbaceous cover crops in olive groves at high rabbit densities, where other palatable species (e.g., B. rubens ) are strongly consumed, thus contributing to soil conservation and improvement in olive groves with soils already degraded by erosion. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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17. Latest extension of the Laujar fault in a convergence setting (Sierra Nevada, Betic Cordillera).
- Author
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Martínez-Martos, Manuel, Galindo-Zaldívar, Jesus, Sanz de Galdeano, Carlos, García-Tortosa, Francisco Juan, Martínez-Moreno, Francisco José, Ruano, Patricia, González-Castillo, Lourdes, and Azañón, José Miguel
- Subjects
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GEOLOGIC faults , *FOLDS (Geology) , *MAGNETOTELLURICS , *FAULT zones , *METAMORPHIC rocks - Abstract
The present-day relief of the Betic Cordillera formed since the Late Miocene through the regional N-S to NW-SE Africa-Eurasia convergence that developed large folds. The Laujar Fault Zone is a south-dipping E-W oriented structure located at the northern boundary of the Alpujarran Corridor Neogene intramontane basin, which separates Sierra Nevada and Sierra de Gador antiforms, in the Internal Zones of the Betic Cordillera. The fault zone acted in a first stage as a dextral strike-slip fault. Currently it moves as a normal fault evidenced by striated calcretes, also in agreement with regional continuous GPS (CGPS) data that support the hypothesis of an active N-S extension in the fault area. In order to analyse the deep geometry of the Laujar Fault Zone, we combined several geophysical techniques (gravity, magnetic, electric resistivity tomography and audio-magnetotelluric data) with field geological observations. Fault surfaces seem to join at a southward-dipping shallow detachment level, including faults covered by the sedimentary infill. The fault zone was developed in a previously weakened area by wrench faults parallel to the Alpujarran Corridor. The recent normal activity of this fault zone may be a consequence of a change in the Africa-Eurasia convergence orientation, which implies a decrease in the N-S compression component. This structure along the southern limb of Sierra Nevada antiform evidences the gravitational collapse of previously thickened crust in a regional compressional context simultaneous to metamorphic core uplift. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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18. Fibrous clay mineral authigenesis induced by fluid-rock interaction in the Galera fault zone (Betic Cordillera, SE Spain) and its influence on fault gouge frictional properties.
- Author
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Sánchez-Roa, Catalina, Jiménez-Millán, Juan, Abad, Isabel, Faulkner, Daniel R., Nieto, Fernando, and García-Tortosa, Francisco J.
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CLAY minerals , *AUTHIGENESIS , *FAULT zones , *FAULT gouge - Abstract
This study presents a mineralogical and mechanical analysis of the clay-rich materials and structures identified in the Galera Fault Zone, southern Spain that formed as a consequence of active deformation processes affecting this seismically active region. Significant differences in clay mineral assemblages and chemical composition were identified in rocks from the Galera Fault Zone, through a series of analytical techniques including XRD, SEM, TEM and XRF. Three distinct mineral assemblages were identified: 1) wall-rock assemblages including white marls and dark lutite layers, with the latter also found in injection features. Their assemblage includes dolomite, gypsum, quartz, calcite and phyllosilicates 2) smectite- and palygorskite-rich fault gouges formed on materials from the upper part of the stratigraphic sequence at the NE area of the fault (Galera Village), and 3) sepiolite-rich gouges in areas of the lower part of the stratigraphic sequence at the central SW segment of the fault (Rambla de los Pilares). Fibrous clay-rich gouges were formed by hydrothermal alteration during periods of fluid-rock interaction that was concentrated in fault planes and fractures. Their mineralogy is dominated by authigenic Mg-rich fibrous clay minerals; sepiolite, precipitated directly from an Mg-rich fluid; and palygorskite as the product of the interaction of the fluid with the Al-rich host rock. Experimental data from frictional sliding experiments on these clay-rich fault gouges reveal strong differences in their mechanical properties. Towards the north-eastern areas of the fault, the smectite- and palygorskite-rich gouge has a low friction coefficient (0.17 wet and 0.59 under vacuum) and its values of the friction stability parameter (a–b) are always positive indicating a stable regime that could be related with creeping and stable-sliding processes. In the central-south-western segment, however, the gouge is rich in authigenic sepiolite and presents complete absence of smectite. The higher friction coefficient (0.47 wet and 0.68 under vacuum) and negative values of a–b for this gouge suggest a more neutral to unstable regime that could favour earthquake nucleation. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
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19. Role of prey and intraspecific density dependence on the population growth of an avian top predator.
- Author
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Fernandez-de-Simon, Javier, Díaz-Ruiz, Francisco, Cirilli, Francesca, Tortosa, Francisco S., Villafuerte, Rafael, and Ferreras, Pablo
- Subjects
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PREDATION , *BIRD populations , *ECOSYSTEMS , *COMPETITION (Biology) , *EUROPEAN rabbit , *BUBO bubo - Abstract
Exploring predator–prey systems in diverse ecosystems increases our knowledge about ecological processes. Predator population growth may be positive when conspecific density is low but predators also need areas with prey availability, associated with competition, which increases the risk of suffering losses but stabilises populations. We studied relationships between European rabbits Oryctolagus cuniculus (prey) and adult eagle owls Bubo bubo (predators) in south-western Europe. We assessed models explaining the predator population growth and stability. We estimated the abundance of rabbits and adult eagle owls during three years in eight localities of central-southern Spain. We explored models including rabbit and adult eagle owl abundance, accounting for yearly variations and including the locality as a random variable. We found that population growth of adult eagle owls was positive in situations with low conspecific abundance and tended to be negative but approaching equilibrium in situations of higher conspecific abundance. Population growth was also positively related to previous summer rabbit density when taking into account eagle owl conspecific abundance, possibly indicating that rabbits may support recruitment. Furthermore, abundance stability of adult eagle owls was positively related to previous winter–spring rabbit density, which could suggest predator population stabilisation through quick territory occupation in high-quality areas. These results exemplify the trade-off between prey availability and abundance of adult predators related to population growth and abundance stability in the eagle owl–rabbit system in south-western Europe. Despite rabbits have greatly declined during the last decades and eagle owls locally specialise on them, eagle owls currently have a favourable conservation status. As eagle owls are the only nocturnal raptor with such dependence on rabbits, this could point out that predators may overcome prey decreases in areas with favourable climate and prey in the absence of superior competitors with similar foraging mode. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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20. Effects of a fiber-rich diet on physiology and survival of farm-reared red-legged partridges (Alectoris rufa)
- Author
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Millán, Javier, Gortázar, Christian, J. Buenestado, Francisco, Rodrıguez, Pablo, S. Tortosa, Francisco, and Villafuerte, Rafael
- Subjects
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RED-legged partridge , *PARTRIDGES - Abstract
The sudden shift from a commercial energy-rich, fiber-poor diet to natural food is assumed as one of the causes of the low success of gamebird restocking. We fed farmed red-legged partridge (Alectoris rufa) chicks with a diet rich in fiber from their first month of life to the time of their release to assess the possible effects on morphometric characteristics and plasma biochemistry and whether those effects enhance survival after release into the wild. At the time of release, treated partridges showed heavier gizzards and bursas of Fabricius and longer small intestines than control birds fed commercial feed. Treated birds had also smaller pectoral muscles, lighter spleens and lower plasma levels of proteins, glucose, cholesterol and triglycerides. After release and radiotracking in a hunting area, we found no differences in the survival between both groups. Survival at the end of the study (day 39) was 58.3±14.2% for the control group and 24.2±13.8% for the treated group. The fiber-rich diet seems to have important effects on the physiology of the red-legged partridge, not always taken into account in previous studies. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
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