Deformation during exhumation of medium‐ and high‐grade metamorphic rocks in the Variscan chain in northern Sardinia (Italy)     

Rodolfo Carosi  Chiara Frassi  Chiara Montomoli 《Geological Journal》2009,44(3):280-305

The Anglona and SW Gallura regions represent key places to investigate the tectonic evolution of medium‐ and high‐grade metamorphic rocks cropping out in northern Sardinia (Italy). From south to north we distinguish two different metamorphic complexes recording similar deformation histories but different metamorphic evolution: the Medium Grade Metamorphic Complex (MGMC) and the High Grade Metamorphic Complex (HGMC). After the initial collisional stage (D1 deformation phase), both complexes were affected by three contractional deformational phases (D2, D3 and D4) followed by later extensional tectonics. The D2 deformation phase was the most significant event producing an important deformation partitioning that produced localized shearing and folding domains at the boundary between the two metamorphic complexes. We highlight the presence of two previously undocumented systems of shear belts with different kinematics but analogous orientation in the axial zone of Sardinia. They became active at the boundary between the MGMC and HGMC from the beginning of D2. They formed a transpressive regime responsible for the exhumation of the medium‐ and high‐grade metamorphic rocks, and overall represent a change from orthogonal to orogen‐parallel tectonic transport. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Shalstab mathematical model and WorldView-2 satellite images to identification of landslide-susceptible areas     

König  Téhrrie  Kux  Hermann J. H.  Mendes  Rodolfo M. 《Natural Hazards》2019,97(3):1127-1149

Natural Hazards - Natural hazards, occurring all over the world, may become a disaster when humans and nature interact. In Brazil, landslides triggered by heavy rainfall are the most common...  相似文献   

On the impact of wind on the development of wave field during storm Britta     

Xiaoli Guo Larsén  Jianting Du  Rodolfo Bolaños  Søren Larsen 《Ocean Dynamics》2017,67(11):1407-1427

The observation of extreme waves at FINO 1 during storm Britta on the 1st November 2006 has initiated a series of research studies regarding the mechanisms behind. The roles of stability and the presence of the open cell structures have been previously investigated but not conclusive. To improve our understanding of these processes, which are essential for a good forecast of similarly important events offshore, this study revisits the development of storm Britta using an atmospheric and wave coupled modeling system, wind and wave measurements from ten stations across the North Sea, cloud images and Synthetic Aperture Radar (SAR) data. It is found here that a standard state-of-the-art model is capable of capturing the important characteristics of a major storm like Britta, including the storm path, storm peak wind speed, the open cells, and peak significant wave height (H _s ) for open sea. It was also demonstrated that the impact of the open cells has negligible contribution to the development of extreme H _s observed at FINO 1. At the same time, stability alone is not sufficient in explaining the development of extreme H _s . The controlling conditions for the development of Britta extreme H _s observed at FINO 1 are the persistent strong winds and a long and undisturbed fetch over a long period.  相似文献   

Tsunami hydrodynamic force on a building using a SPH real-scale numerical simulation     

Klapp  Jaime  Areu-Rangel  Omar S.  Cruchaga  Marcela  Aránguiz  Rafael  Bonasia  Rosanna  Godoy  Mauricio J.  Silva-Casarín  Rodolfo 《Natural Hazards》2020,100(1):89-109

Natural Hazards - One of the most important aspects in tsunami studies is the behaviour of the wave when it approaches the coast. Information on physical parameters that characterize waves is often...  相似文献   

Erratum to: Controls on monthly estuarine residuals: Eulerian circulation and elevation     

Jennifer M. Brown  Rodolfo Bolaños  Alejandro J. Souza 《Ocean Dynamics》2014,64(6):925-925

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Extracting sea level residual in tidally dominated estuarine environments   总被引：1，自引：1，他引：0  

Jennifer M. Brown  Rodolfo Bola?os  Michael J. Howarth  Alejandro J. Souza 《Ocean Dynamics》2012,62(7):969-982

Sea level comprises a mean level, tidal elevation and a residual elevation. Knowledge of what causes maximum water levels is often key in coastal management. However, different methods to extract deviations in water level (residuals) from modelled and observed elevation can give different results. The Dee Estuary, northwest England is a macrotidal estuary that undergoes periodic stratification. It is used here to demonstrate methods to extract the residual water level in response to the following interactive processes: tidal, river-induced stratification and flow, meteorology and waves. Using modelling techniques, the interaction and contribution of different physical processes are investigated. Classical harmonic tidal analysis, model simulations and filtering techniques have been used to “de-tide” the total elevation for short-term (approximately month long) records. Each technique gives a different result highlighting the need to select the correct method for a required study. Analysis of the residual components demonstrates that all processes inducing residuals interact with the tide generating a semi-diurnal residual component. It is suggested that modelling methods enable the full effect of tidal interaction to remain in the residual, whilst harmonic tidal analysis (partly) modify and filtering methods (fully) remove this component of the residual. The analysis methods presented and their influences on the resultant residual are applicable to other study sites. However, when applied specifically to the mouth of the Dee Estuary, the external surge is found to be the main contributor to the total residual, whilst local wind and stratification effects are of secondary importance.  相似文献   

Trace elements in farmed and wild gilthead seabream, Sparus aurata     

Vincenzo Minganti  Giuliana Drava  Rodolfo De Pellegrini  Camilla Siccardi 《Marine pollution bulletin》2010,60(11):2022-2025

In the present study, we sought to determine the concentration of several trace elements (total and organic mercury, selenium, cadmium, lead, arsenic, copper, chromium, iron, manganese, molybdenum, vanadium and zinc) in muscle tissue of gilthead seabream (Sparus aurata), an edible finfish species that is widely cultured in the Mediterranean area. The phenomenon of bioaccumulation and bioamplification (especially of mercury) was investigated by comparing farmed fish with wild specimens of the same species. Farmed specimens showed mercury and arsenic concentrations significantly lower than wild specimens, and no relationship was found between mercury concentration and body size. The lower level of methylmercury in farmed fish has important implications for consumer health.  相似文献   

Corrigendum to “Survival and movements of Magellanic penguins rehabilitated from oil fouling along the coast of South America, 2000–2010” [Marine Pollut. Bull. 64 (2012) 1309–1317]     

Valeria Ruoppolo  Ralph Eric Thijl Vanstreels  Eric J. Woehler  Sergio Andres Rodríguez Heredia  Andréa Corrado Adornes  Rodolfo Pinho da Silva-Filho  Ricardo Matus  Carla Poleschi  Karen Griot  Cristiane K. Miyaji Kolesnikovas  Patrícia Serafini 《Marine pollution bulletin》2013,66(1-2):265

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Sources and behavior of arsenic and trace elements in groundwater and surface water in the Poopó Lake Basin,Bolivian Altiplano     

Oswaldo Eduardo Ramos Ramos  Luis Fernando Cáceres  Mauricio Rodolfo Ormachea Muñoz  Prosun Bhattacharya  Israel Quino  Jorge Quintanilla  Ondra Sracek  Roger Thunvik  Jochen Bundschuh  Maria Eugenia García 《Environmental Earth Sciences》2012,66(3):793-807

Water management in semiarid and arid catchments such as the Poopó Lake Basin requires improved understanding of the complex behavior of the various contaminants, which affect the drinking water quality and considered as crucial for sustainable development of the region. Mechanisms of arsenic (As) release in the surface and groundwater were studied. Hydrochemical data for surface water (4 samples) and groundwater (28 samples) were collected in a small watershed in the Poopó catchment at the highland of the Bolivian Andes (Altiplano). All of them show high electrical conductivity values and moderately oxidizing conditions. The surface water contains high concentration of sulfate and the trace elements As, Zn and Pb in the zone affected by acid mine drainage. There is a large variability of the concentration of As and of the trace elements in the groundwater in the five different regions within the Poopó catchment. The metal concentrations sensitive to changes of redox state and results of speciation modeling suggest that As (V) is a predominant aqueous species, which conforms to the prevailing oxidizing conditions in the shallow groundwater environment. Two generalized trends for As distribution were identified in groundwater: (a) high concentrations are found in the arid zone (100–250 μg/L) in the southern (region III) and in the northwestern (region V) regions, and (b) low concentrations (<50 μg/L) are found in the remaining part of the basin (region I, II and IV). However, the spatial distribution within these regions needs to be investigated further. A conclusion from the present study is that there are multiple sources of As as well as other trace elements (such as Cd, Mn and Zn) in the Poopó Lake Basin. Among the sources and the processes which led to the mobility of As and other trace metals in the region are: (a) weathering of sulfide minerals, (b) oxidation of pyrite and/or arsenopyrite in mineralized areas and (c) desorption from hydrous ferric oxide (HFO) surfaces. In non-mining areas, volcanic ash is suggested to be a significant source of As.  相似文献   

Identification of High Frequency Pulses from Earthquake Asperities Along Chilean Subduction Zone Using Strong Motion     

S. Ruiz  E. Kausel  J. Campos  G. R. Saragoni  R. Madariaga 《Pure and Applied Geophysics》2011,168(1-2):125-139

The Chilean subduction zone is one of the most active of the world with M?=?8 or larger interplate thrust earthquakes occurring every 10?years or so on the average. The identification and characterization of pulses propagated from dominant asperities that control the rupture of these earthquakes is an important problem for seismology and especially for seismic hazard assessment since it can reduce the earthquake destructiveness potential. A number of studies of large Chilean earthquakes have revealed that the source time functions of these events are composed of a number of distinct energy arrivals. In this paper, we identify and characterize the high frequency pulses of dominant asperities using near source strong motion records. Two very well recorded interplate earthquakes, the 1985 Central Chile (Ms?=?7.8) and the 2007 Tocopilla (Mw?=?7.7), are considered. In particular, the 2007 Tocopilla earthquake was recorded by a network with absolute time and continuos recording. From the study of these strong motion data it is possible to identify the arrival of large pulses coming from different dominant asperities. The recognition of the key role of dominant asperities in seismic hazard assessment can reduce overestimations due to scattering of attenuation formulas that consider epicentral distance or shortest distance to the fault rather than the asperity distance. The location and number of dominant asperities, their shape, the amplitude and arrival time of pulses can be one of the principal factors influencing Chilean seismic hazard assessment and seismic design. The high frequency pulses identified in this paper have permitted us to extend the range of frequency in which the 1985 Central Chile and 2007 Tocopilla earthquakes were studied. This should allow in the future the introduction of this seismological result in the seismic design of earthquake engineering.  相似文献