Late Cenozoic brittle deformation in the Southern Patagonian Andes: Record of plate coupling/decoupling during variable subduction?          下载免费PDF全文

Vanesa Barberón  Christian Sue  Matías Ghiglione  Gonzalo Ronda  Eugenio Aragón 《地学学报》2018,30(4):296-309

The Andes of southern Patagonia experienced a Miocene shift towards faster and higher angle subduction followed by the approach and collision of the Chile oceanic ridge. We present a kinematic study characterizing palaeostress fields computed from brittle tectonics to better constrain upper crustal deformation during this complex scenario. Although previous studies already suggested variable kinematics, it is striking that in a long‐lasting subduction environment, the computed palaeostress tensors are mostly strike‐slip (55%), while 35% are extensional, and only 10% compressive which are concentrated along a main frontal thrust. Cross‐cutting relationships and synsedimentary deformation indicate that a long‐lived strike‐slip regime was punctuated by a lower Miocene extensional event in the foreland before the main compressional event. The results are discussed in contrasting geodynamic models of plate coupling/decoupling versus direction and rate of convergence of the subducting plate, to explain the main mechanisms that control back‐arc deformation.  相似文献   

Seismic microzoning of Arica and Iquique,Chile     

Alix Becerra  Luis Podestá  Roberto Monetta  Esteban Sáez  Felipe Leyton  Gonzalo Yañez 《Natural Hazards》2015,79(1):567-586

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Ground Penetrating Radar Applied to Monumental Stone Conservation: Application to the Rock Necropolis of San Vítor de Barxacova in NW Spain     

Solla  Mercedes  Buceta-Bruneti  Gonzalo  Elseicy  Ahmed  Nieto-Muñiz  Breogán 《Surveys in Geophysics》2022,43(5):1587-1606

Surveys in Geophysics - This paper deals with the application of the Ground Penetrating Radar (GPR) method in the assessment of stone monuments. Compilation of published works and a discussion of...  相似文献   

Improving the Wishart Synthetic Aperture Radar image classifications through Deterministic Simulated Annealing     

Francisco J. Sánchez-Lladó  Gonzalo Pajares  Carlos López-Martínez 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(6):845-857

This paper proposes the use of Deterministic Simulated Annealing (DSA) for Synthetic Aperture Radar (SAR) image classification for cluster refinement. We use the initial classification provided by the maximum-likelihood classifier based on the complex Wishart distribution that is then supplied to the DSA optimization approach. The goal is to improve the classification results obtained by the Wishart approach. The improvement is verified by computing a cluster separability coefficient. During the DSA optimization process, for each iteration and for each pixel, two consistency coefficients are computed taking into account two kinds of relations between the pixel under consideration and its neighbors. Based on these coefficients and on the information coming from the pixel itself, it is re-classified. Several experiments are carried out to verify that the proposed approach outperforms the Wishart strategy. We try to improve the classification results by considering the spatial influences received by a pixel through its neighbors. Finally, a link about the contribution of DSA to thematic mapping is also established.  相似文献   

Toward reduction of artifacts in fused images     

Mario Lillo-Saavedra  Consuelo Gonzalo  Octavio Lagos 《International Journal of Applied Earth Observation and Geoinformation》2011

Most fusion satellite image methodologies at pixel-level introduce false spatial details, i.e. artifacts, in the resulting fused images. In many cases, these artifacts appears because image fusion methods do not consider the differences in roughness or textural characteristics between different land covers. They only consider the digital values associated with single pixels. This effect increases as the spatial resolution image increases. To minimize this problem, we propose a new paradigm based on local measurements of the fractal dimension (FD). Fractal dimension maps (FDMs) are generated for each of the source images (panchromatic and each band of the multi-spectral images) with the box-counting algorithm and by applying a windowing process. The average of source image FDMs, previously indexed between 0 and 1, has been used for discrimination of different land covers present in satellite images. This paradigm has been applied through the fusion methodology based on the discrete wavelet transform (DWT), using the à trous algorithm (WAT). Two different scenes registered by optical sensors on board FORMOSAT-2 and IKONOS satellites were used to study the behaviour of the proposed methodology. The implementation of this approach, using the WAT method, allows adapting the fusion process to the roughness and shape of the regions present in the image to be fused. This improves the quality of the fused images and their classification results when compared with the original WAT method.  相似文献   

Bloom of the Yessotoxin producing dinoflagellate Protoceratium reticulatum (Dinophyceae) in Northern Chile     

Gonzalo Álvarez  Eduardo Uribe  Rosario Díaz  Mauricio Braun  Carmen Mariño  Juan Blanco 《Journal of Sea Research》2011,65(4):427-434

Potential spawning habitat is defined as the area where environmental conditions are suitable for spawning to occur. Spawning adult data from the first quarter (January–March) of the International Bottom Trawl Survey have been used to study the inter-annual variability of the potential spawning habitat of North Sea plaice from 1980 to 2007. Generalised additive models (GAM) were used to create a model that related five environmental variables (depth, bottom temperature and salinity, seabed stress and sediment type) to presence–absence and abundance of spawning adults. Then, the habitat model was applied each year from 1970 to 2007 to predict inter-annual variability of the potential spawning habitat. Predicted responses obtained by GAM for each year were mapped using kriging. A hierarchical classification associated with a correspondence analysis was performed to cluster spawning suitable areas and to determine how they evolved across years. The potential spawning habitat was consistent with historical spawning ground locations described in the literature from eggs surveys. It was also found that the potential spawning habitat varied across years. Suitable areas were located in the southern part of the North Sea and along the eastern coast of England and Scotland in the eighties; they expanded further north from the nineties. Annual survey distributions did not show such northward expansion and remained located in the southern North Sea. This suggests that this species' actual spatial distribution remains stable against changing environmental conditions, and that the potential spawning habitat is not fully occupied. Changes in environmental conditions appear to remain within plaice environmental ranges, meaning that other factors may control the spatial distribution of plaice spawning habitat.  相似文献   

Transneptunian Object Ephemeris Service (TNOEPH)     

Granvik  Mikael  Virtanen  Jenni  Muinonen  Karri  Bowell  Edward  Koehn  Bruce  Tancredi  Gonzalo 《Earth, Moon, and Planets》2003,92(1-4):73-78

We present a web service called TNOEPH ( http://asteroid.lowell.edu/)for ephemeris uncertainty prediction and dynamical classification ofshort-arc trans\-neptunian objects (TNOs). User-supplied observations are transformed to a rigorous sky-plane uncertainty map using the technique of statistical orbital ranging. We show examples of thegrowth of ephemeris uncertainty with time, and give the probabilities ofdifferent dynamical classifications for a few short-arc TNOs.  相似文献   

Cycles in the scaling properties of length-of-day variations     

Jose Alvarez-Ramirez  Leonardo Dagdug  Gonzalo Rojas 《Journal of Geodynamics》2010,49(2):105-110

Variations in the length-of-day (LOD) reflect the effects of several mechanisms in the Earth's rotation dynamics, including Earth–Sun and Earth–Moon line-up, geomagnetic effects and gravitational changes. Several studies showed that signatures of cycles occurring over a wide range of time scales are present in the LOD variations. The present work uses a fractal scaling study based on detrended fluctuation analysis (DFA) to study persistence of LOD variations and to provide insights in the different cycling mechanisms. The results showed that that the LOD variations are persistent over a wide range of time scales, meaning that an increment (resp., decrement) is more likely to be followed by an increment (resp., decrement). The temporal variation of the scaling exponent obtained from the DFA showed that several cycles already reported from the direct LOD variations analysis are inherited by the scaling properties. Inter-annual cycles, including 4.3 and 18.6 years cycles, are linked to the variations of the stochastic dynamics of LOD fluctuations. In this way, the 18.6 years cycle attains a period where variations are mostly affected by white noise effects, reducing the predictability of the LOD anomalies. The results are discussed in terms of the different lunar tidal and core–mantle mechanisms and related to recent results in the literature.  相似文献   

Holocene environmental change in southern Spain deduced from the isotopic record of a high-elevation wetland in Sierra Nevada     

Antonio García-Alix  Gonzalo Jiménez-Moreno  R. Scott Anderson  Francisco J. Jiménez Espejo  Antonio Delgado Huertas 《Journal of Paleolimnology》2012,48(3):471-484

Small lakes and wetlands from high elevation within the Sierra Nevada Range (southern Spain) preserve a complete post-glacial Holocene record. Isotopic, TOC and C/N analyses, carried out on a sediment core, show various stages in the evolution of the Borreguiles de la Virgen, which today constitute a small bog at about 2,950?m above sea level. Glacial erosion generated a cirque depression, which became a small lake during the first phase of infilling (from?8,200 to 5,100?cal?yr BP), as suggested by sedimentary evidence, including an atomic C/N ratio generally below 20, low TOC values and the highest ??¹³C and ??¹⁵N values of the record. These results imply significant algal productivity, which is confirmed by the microscopic algal remains. Drier conditions became established progressively in this area from?5,100 to 3,700?cal?yr BP. Subsequently, the lake evolved into a bog as shown by geochemical evidence (C/N ratios above 20, high TOC content and low ??¹³C values). Unstable conditions prevailed from?3,600 to 700?cal?yr BP; an extremely low sedimentation rate and scarcity of data from this period do not allow us to make a coherent interpretation. Fluctuating conditions were recorded during the last?~700?cal?yr BP, with wetter conditions prevailing during the first part of the interval (with C/N rate below 20) up to 350?years ago. In general, a gradual trend toward more arid conditions occurred since?~6,900?cal?yr BP, with a further increase in aridity since?~5,100?cal?yr BP. This evidence is consistent with other contemporaneous peri-Mediterranean records.  相似文献   

Regional droughts in southern South America   总被引：1，自引：1，他引：0  

J. L. Minetti  W. M. Vargas  A. G. Poblete  L. R. de la Zerda  L. R. Acuña 《Theoretical and Applied Climatology》2010,102(3-4):403-415

From a regional inventory of monthly droughts, which was evaluated in six regions of southern South America, the seasonal occurrence of the phenomenon and its persistence together with the duration of monthly and annual sequences, extreme events, and other statistical estimates of the proposed index have been studied. In a primary analysis, it is possible to observe that regions present different behaviors regarding the duration of dry sequences, with more persistence in the Argentinean continental region. Temporal behaviors of the annual indexes have also been analyzed, in the attempt to determine any aspects of the impact of global warming. Through this analysis, the presence of long favorable tendencies regarding precipitations or the inverse of droughts occurrence are confirmed for the eastern Andes Mountains in Argentina (ARG) with its five sub-regions (Northwest Argentina-NWA, Northeast Argentina-NEA, Humid Pampa-HP, West-Centre Provinces-WC and Patagonia-PAT, and the inverse over the central region of Chile (CHI). Other climatic great-scale changes are interdecadales variations and variances explained according to ENSO.  相似文献