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11.
Neogene tectonic activity (Betic Orogeny) along the southern plate boundary of Iberia, as it converged with Africa and the Alboran Plate was inserted between them, propagated along Iberia's west side as far north as Galicia, northwest Spain. As the activity propagated northward, it reactivated structures formed during the Paleozoic (Hercynian), the Early Cretaceous opening of the northern North Atlantic and the Bay of Biscay, and the Paleogene Pyrenean Orogeny when Iberia collided with Eurasia. Recent earthquakes indicate that this tectonism is still active today as far north as northwest Spain. 相似文献
12.
O. Bartoli L. Tajčmanová B. Cesare A. Acosta‐Vigil 《Journal of Metamorphic Geology》2013,31(7):775-789
Stromatic metatexites occurring structurally below the contact with the Ronda peridotite (Ojén nappe, Betic Cordillera, S Spain) are characterized by the mineral assemblage Qtz+Pl+Kfs+Bt+Sil+Grt+Ap+Gr+Ilm. Garnet occurs in low modal amount (2–5 vol.%). Very rare muscovite is present as armoured inclusions, indicating prograde exhaustion. Microstructural evidence of melting in the migmatites includes pseudomorphs after melt films and nanogranite and glassy inclusions hosted in garnet cores. The latter microstructure demonstrates that garnet crystallized in the presence of melt. Re‐melted nanogranites and preserved glassy inclusions show leucogranitic compositions. Phase equilibria modelling of the stromatic migmatite in the MnO–Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2–O2–C (MnNCaKFMASHOC) system with graphite‐saturated fluid shows P–T conditions of equilibration of 4.5–5 kbar, 660–700 °C. These results are consistent with the complete experimental re‐melting of nanogranites at 700 °C and indicate that nanogranites represent the anatectic melt generated immediately after entering supersolidus conditions. The P–T estimate for garnet and melt development does not, however, overlap with the low‐temperature tip of the pure melt field in the phase diagram calculated for the composition of preserved glassy inclusions in garnet in the Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O (NCKFMASH) system. A comparison of measured melt compositions formed immediately beyond the solidus with results of phase equilibria modelling points to the systematic underestimation of FeO, MgO and CaO in the calculated melt. These discrepancies are present also when calculated melts are compared with low‐T natural and experimental melts from the literature. Under such conditions, the available melt model does not perform well. Given the presence of melt inclusions in garnet cores and the P–T estimates for their formation, we argue that small amounts (<5 vol.%) of peritectic garnet may grow at low temperatures (≤700 °C), as a result of continuous melting reactions consuming biotite. 相似文献
13.
Assessment of salinity status in intensively cultivated soils under semiarid climate, Murcia, SE Spain 总被引：1，自引：0，他引：1
J.A. Acosta A. FazB. Jansen K. KalbitzS. Martínez-Martínez 《Journal of Arid Environments》2011,75(11):1056-1066
This research presents the results from the assessment of the salinity status of a highly productive agricultural area, under a semiarid climate. The objectives were to: identify the origin of salts, assess seasonal changes of salt contents, and examine spatio-temporal and vertical variability of the presence and composition of salts. Soil samples from the surface horizon, and topsoil samples, soil profiles, water samples and salt precipitates on aggregates were collected in January and July 2009. High electrical conductivity was mainly the result of the poor low quality irrigation water. However, ions responsible for salinity were chlorides, sulfates, calcium, magnesium and sodium, while phosphates, ammonium, nitrates, and potassium were associated with fertilizers. SEM-EDX (scanning electron microscope-energy dispersive X-ray) analyses suggested that calcium sulfate came from both irrigation water and from a pedogenic source, as indicated by differences in crystal morphology and seasonal occurrence, which indicates that primary salinization is also a contributor to soil salinity in the area studied. Significant differences were reported between seasons. The electrical conductivity and concentrations of chloride, sulfates, calcium, magnesium, sodium, potassium, and nitrite are significantly higher in July. The observed differences were caused by the effect of soluble salt movement through evaporation and capillary rise, resulting in precipitation of salts on the surface. Multivariable, GIS and advanced laboratory analysis have confirmed to be useful techniques to identify the salts sources, spatial distribution of anions, and identification of vulnerable areas. 相似文献
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Boris F. Ochoa‐Tocachi Wouter Buytaert Bert De Bièvre Rolando Célleri Patricio Crespo Marcos Villacís Carlos A. Llerena Luis Acosta Mauricio Villazón Mario Guallpa Junior Gil‐Ríos Paola Fuentes Dimas Olaya Paúl Viñas Gerver Rojas Sandro Arias 《水文研究》2016,30(22):4074-4089
Changes in land use and land cover are major drivers of hydrological alteration in the tropical Andes. However, quantifying their impacts is fraught with difficulties because of the extreme diversity in meteorological boundary conditions, which contrasts strongly with the lack of knowledge about local hydrological processes. Although local studies have reduced data scarcity in certain regions, the complexity of the tropical Andes poses a big challenge to regional hydrological prediction. This study analyses data generated from a participatory monitoring network of 25 headwater catchments covering three of the major Andean biomes (páramo, jalca and puna) and links their hydrological responses to main types of human interventions (cultivation, afforestation and grazing). A paired catchment setup was implemented to evaluate the impacts of change using a ‘trading space‐for‐time’ approach. Catchments were selected based on regional representativeness and contrasting land use types. Precipitation and discharge have been monitored and analysed at high temporal resolution for a time period between 1 and 5 years. The observed catchment responses clearly reflect the extraordinarily wide spectrum of hydrological processes of the tropical Andes. They range from perennially humid páramos in Ecuador and northern Peru with extremely large specific discharge and baseflows, to highly seasonal, flashy catchments in the drier punas of southern Peru and Bolivia. The impacts of land use are similarly diverse and their magnitudes are a function of catchment properties, original and replacement vegetation and management type. Cultivation and afforestation consistently affect the entire range of discharges, particularly low flows. The impacts of grazing are more variable but have the largest effect on the catchment hydrological regulation. Overall, anthropogenic interventions result in increased streamflow variability and significant reductions in catchment regulation capacity and water yield, irrespective of the hydrological properties of the original biome. Copyright © 2016 The Authors. Hydrological Processes. Published by John Wiley & Sons Ltd. 相似文献
16.
A method for classifying pre‐stack seismic data based on amplitude–frequency attributes and self‐organizing maps 
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P. Llanes A. Muñoz A. Muñoz-Martín J. Acosta P. Herranz A. Carbó C. Palomo 《Marine Geophysical Researches》2003,24(1-2):91-112
As part of the ‘National Hydrographic and Oceanographic Research Plan for the Spanish Exclusive Economic Zone’, multibeam bathymetry and seismic reflection profiles were obtained in the Canary Islands aboard the R/V Hespérides. The submarine flanks of the Anaga offshore extension of Tenerife Island are here studied to analyze its geomorphology. In the north sector of the Anaga submarine massif, the extension of the Anaga Debris Avalanche has been mapped for the first time, and a volume of 36 km3 was calculated. The relationship between the Anaga and Orotava Debris Avalanches is also described. Faulting has been recognized as a key process for the occurrence of debris avalanches and the growth of volcanic lineaments. Moreover, faulting affects previous structures and the channelling of debris flows. Structural analysis shows the typical radial pattern of an oceanic island. In addition, a NE-SW dominant direction of faulting was obtained, consistent with the Tenerife Island structural trend seen in the Anaga Massif and Cordillera Dorsal. NW-SE and E-W are two other main trends seen in the area. Special interest is manifest in two long faults: ‘Santa Cruz Fault’ bounds the southern edge of Anaga offshore Massif with a length of 50 km and a direction that changes from NE-SW to almost E-W. The Güimar Debris Avalanche was probably channeled by this fault. The ‘Guayotá Fault’ was recognized in several seismic profiles with a N-S direction that changes towards NW-SE at its southern end. This fault affects the more recent sediments with a vertical offset of 25–30 m, along 60~km. It has been interpreted as a transpressive strike-slip fault.ZEE Working Group**F. Carrilloa, C. Matéa, M. Ballesterosb, M. Vaquerob, J. Martín-Dávillac and J.A. MaríncaInstituto Hidrográfico de la Marina. CádizbInstituto Español de Oceanografía. Madrid.cReal Observatorio de la Armada. S. Fernando, Cádiz. 相似文献
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J. Acosta A. Muñoz P. Herranz C. Palomo M. Ballesteros M. Vaquero E. Uchupi 《Geo-Marine Letters》2001,21(3):123-130
Pockmarks ranging in width from <10 to 700 m, and with reliefs of 2 to 55 m were discovered in the Ibiza Channel and on the Balearic Promontory, Western Mediterranean, during a multibeam survey. In the Ibiza Channel the larger structures are found within a field of small craters less than 10 m wide and 5 m deep which give the seafloor an "orange peel" texture. The abundant 30 Ma-Present volcanic structures in the region suggests that most of the craters may have been formed by the escape of gases and associated waters via faults from a hydrothermal field beneath the surficial sediments. Others may be the result of neotectonism. 相似文献
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Impacts of environmental stressors on the water resources of intensively managed hydrologic systems 下载免费PDF全文
下载免费PDF全文 Watersheds are complex systems due to their surface and subsurface spatially connected water fluxes and biochemical processes that shape Earth's critical zone. In intensively managed landscapes, the implementation of watershed management practices (WMPs) regulate their short‐term responses, whereas climate variability controls the long‐term processes. Understanding their responses to anthropogenic and natural stressors requires a holistic approach that takes into account their multiscale spatio‐temporal linkages. The objective of this study was to simulate the impacts of spatially and temporally varying WMPs and projected climate changes on the surface and groundwater resources in the Upper Sangamon River Basin (USRB), a watershed in central Illinois greatly impacted by agricultural and industrial operations. The physically based hydrologic model MIKE‐SHE was used to simulate the hydrologic responses of the basin to different WMPs and climatic conditions. The simulation of a WMP was varied spatially across the basin to determine the spectrum of responses and critical conditions. In general, the wetlands and forested riparian buffer scenarios were found to cause a reduction in the average streamflow, whereas crop rotation had varied responses depending on the location of implementation and the climate condition assumed. Reductions of up to 30% in the average streamflow were found for the forested riparian buffer under the ESM 2M climate projections, whereas an increase of up to 13% with the crop rotation schemes under CM3 climate was predicted. The model results showed that the installation of tile drains across the USRB increased the water table depth (from ground level) by up to 56%, making crop production possible. Groundwater level in USRB appeared to be more sensitive to future climatic conditions than to WMP implementation. The impacts of WMPs are determined to depend on the climate conditions under which they are applied. Investigating individual and combined stressors' effects over the critical zone at a watershed scale can lead to a more comprehensive analysis of the risk and trade‐offs in every managerial decision that will enable an efficient use of resources. 相似文献
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Víctor Alcaraz‐González Rubén Horacio López‐Bañuelos Jean‐Philippe Steyer Hugo Oscar Méndez‐Acosta Víctor González‐Álvarez Carlos Pelayo‐Ortiz 《洁净——土壤、空气、水》2012,40(9):941-949
Anaerobic digestion (AD) is a highly nonlinear time‐varying process commonly used for biological wastewater treatment, which is subject to large disturbances of both influent concentrations, and flow rates that may lead the process to a breakdown. In order to compensate the effect of these disturbances, the dynamics of the main state variables – including biomass – must be closely monitored and used to improve the process performance. However, AD processes still suffer from a lack of reliable and cheap sensors of key process variables to insure the right process operation. This has led to the development of estimation schemes, which infer the information of such key variables from the available measurements. Nevertheless, reliable measurements are not always possible to get because these readings may be corrupted by noise or erroneous due to sensor failures and as a consequence, they may lead to deteriorated control efforts and the eventual crash of the AD process. In this article, we propose an integrated system for the detection, isolation, and analysis of faults in AD processes by using interval observers (IO). The proposed approach was experimentally implemented on a 1‐m3 pilot scale anaerobic digester. Based on the comparison between the measured outputs and their corresponding estimates, results show that this approach was able to detect sensor failures as well as faults in the basic hypotheses made during the design step. 相似文献