Denudation and retreat of the Serra do Mar escarpment in southern Brazil derived from in situ‐produced 10Be concentration in river sediment          下载免费PDF全文

André A. R. Salgado  Breno R. Marent  Luís F. S. Cherem  Didier Bourlès  Leonardo J. C. Santos  Régis Braucher  Helen N. Barreto 《地球表面变化过程与地形》2014,39(3):311-319

The Serra do Mar escarpment, located along the southeastern coast of Brazil, is a high‐elevation passive margin escarpment. This escarpment evolved from the denudation of granites, migmatites and gneisses. The granites outcrop in the form of a ridge along the escarpment crest, due to its differential erosion (‘sugarloaf’ hills) from the surrounding lithologies. Several studies suggest that the passive margin escarpments are actively retreating toward the interior of the continent. However, no prior study has calculated the long‐term denudation rates of Serra do Mar to test this hypothesis. In this study, we measured the in situ‐produced ¹⁰Be concentration in fluvial sediments to quantify the catchment‐wide long‐term denudation rates of the Serra do Mar escarpment in southern Brazil. We sampled the fluvial sediments from ten watersheds that drain both sides of the escarpment. The average long‐term denudation rate of the oceanic side is between 2.1‐ and 2.6‐fold higher than the rate of the continental side: 26.04 ± 1.88 mm ka^‐1 (integrating over between 15.8 ka^‐1 and 46.6 ka^‐1) and 11.10 ± 0.37 mm ka^‐1 (integrating over between 52.9 ka^‐1 and 85.4 ka^‐1), respectively. These rates indicate that the coastal base level is controlling the escarpment retreat toward the continental high lands, which is consistent with observations made at other high‐elevation passive margins around the globe. The results also demonstrate the differential erosion along the Serra do Mar escarpment in southern Brazil during the Quaternary, where drainages over granites had lower average denudation rates in comparison with those over migmatites and gneisses. Moreover, the results demonstrate that the ocean‐facing catchments have been eroded more intensely than those facing the continent. The results also reveal that drainage over the granites decreases the average denudation rates of the ocean‐facing catchments and the ‘sugarloaf’ hills therefore are natural barriers that slowly retreat once they are exhumed. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Transient sediment supply in a high‐altitude Alpine environment evidenced through a 10Be budget of the Etages catchment (French Western Alps)          下载免费PDF全文

Romain Delunel  Peter A. van der Beek  Didier L. Bourlès  Julien Carcaillet  Fritz Schlunegger 《地球表面变化过程与地形》2014,39(7):890-899

Although beryllium‐10 (¹⁰Be) concentrations in stream sediments provide useful synoptic views of catchment‐wide erosion rates, little is known on the relative contributions of different sediment supply mechanisms to the acquisition of their initial signature in the headwaters. Here we address this issue by conducting a ¹⁰Be‐budget of detrital materials that characterize the morphogenetic domains representative of high‐altitude environments of the European Alps. We focus on the Etages catchment, located in the Ecrins‐Pelvoux massif (southeast France), and illustrate how in situ ¹⁰Be concentrations can be used for tracing the origin of the sand fraction from the bedload in the trunk stream. The landscape of the Etages catchment is characterized by a geomorphic transient state, high topographic gradients, and a large variety of modern geomorphic domains ranging from glacial environments to scarcely vegetated alluvial plains. Beryllium‐10 concentrations measured in the Etages catchment vary from ~1 × 10⁴ to 4.5 × 10⁵ atoms per gram quartz, while displaying consistent ¹⁰Be signatures within each representative morphogenetic unit. We show that the basic requirements for inferring catchment‐wide denudation from ¹⁰Be concentration measurements are not satisfied in this small, dynamic catchment. However, the distinct ¹⁰Be signature observed for the geomorphic domains can be used as a tracer. We suggest that a terrestrial cosmogenic nuclide (TCN) budget approach provides a valuable tool for the tracing of material origin in basins where the ‘let nature do the averaging’ principles may be violated. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Erosion rates and sediment budgets in vineyards at 1-m resolution based on stock unearthing (Burgundy, France)   总被引：1，自引：0，他引：1  

Jrme Brenot  Amlie Quiquerez  Christophe Petit  Jean-Pierre Garcia 《Geomorphology》2008,100(3-4):345-355

A new and simple method is developed to efficiently quantify erosion and deposition rates based on stock unearthing measurements. This is applicable to spatial scales ranging from plot to hillslopes, and to time scales ranging from single hydrologic events to centennial scales. The method is applied to a plot area on vineyard hillslopes in Burgundy (Monthélie, France), with measurement of 4328 vine plants. A sediment budget established at the plot scale shows a mean soil lowering of 3.44 ± 1 cm over 20 years, involving a minimal erosion rate of 1.7 ± 0.5 mm yr^− 1. Locally, erosion rates can reach up to 8.2 ± 0.5 mm yr^− 1.This approach allows the sediment redistribution to be mapped and analyzed at 1-m resolution. It provides novel insights into the characterization of erosion patterns on pluri-decennial scales and into the analysis of spatial distribution of erosion processes on cultivated hillslopes.  相似文献   

Metal Concentrations in Plants from Mining Areas in South Morocco: Health Risks Assessment of Consumption of Edible and Aromatic Plants          下载免费PDF全文

Ouafae El Hamiani  Hicham El Khalil  Catherine Sirguey  Ahmed Ouhammou  Gabriel Bitton  Christophe Schwartz  Ali Boularbah 《洁净——土壤、空气、水》2015,43(3):399-407

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Electro‐Oxidation of the Pharmaceutical Furosemide: Kinetics,Mechanism, and By‐Products          下载免费PDF全文

Hugo Olvera‐Vargas  Nihal Oturan  Didier Buisson  Eric D. van Hullebusch  Mehmet A. Oturan 《洁净——土壤、空气、水》2015,43(11):1455-1463

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Equivalent linear substructure approximation of soil–foundation–structure interaction: model presentation and validation     

Dimitris Pitilakis  Didier Clouteau 《Bulletin of Earthquake Engineering》2010,8(2):257-282

An equivalent linear substructure approximation of the soil–foundation–structure interaction is proposed in this paper. Based on the inherent linearity of the approach, the solution of the structural and the soil domain is obtained simultaneously, incorporating the effects of the primary and secondary soil nonlinearities. The proposed approximation is established theoretically and then validated against centrifuge benchmark soil–foundation–structure interaction tests. The equivalent linear substructure approximation is proved to simulate efficiently the effects of the nonlinear soil behavior on the soil–foundation–structure system under a strong earthquake ground motion.  相似文献   

Building frequency fluctuations from continuous monitoring of ambient vibrations and their relationship to temperature variations     

Bertrand?GuillierEmail author  Jean-Luc?Chatelain  Hugo?Perfettini  El?Hadi?Oubaiche  Christophe?Voisin  Rabah?Bensalem  Djamel?Machane  Mustapha?Hellel 《Bulletin of Earthquake Engineering》2016,14(8):2213-2227

Building frequencies (fundamental and higher modes) are a critical parameter especially in the field of structural health monitoring mainly based on the stability of the structural dynamic parameters of individual building (frequencies, damping and modes shape). One of the most used methods to find out these parameters is based on the use on ambient vibration analysis. In this work, we study the fluctuations over a month period of the fundamental frequencies (transverse and longitudinal) of a 3.5-story RC-building made of 2 identical units connected by a structural joint. Time independent building frequencies is a strong assumption; as illustrated by our experiment showing that over an observation period of a month, building frequencies fluctuate of about 3.5 %. A clear correlation is found between the building frequency fluctuations and temperature variations, with a phase-shift interpreted as the characteristic time of heat diffusion within the walls. This allows: (1) determining the thermal diffusivity of the structure, (2) inferring its relative stiffness variations, and (3) showing that its Young modulus varies linearly with temperature.  相似文献   

A spatial cross‐correlation model of spectral accelerations at multiple periods     

Christophe Loth  Jack W. Baker 《地震工程与结构动力学》2013,42(3):397-417

Many seismic loss problems (such as disruption of distributed infrastructure and losses to portfolios of structures) are dependent upon the regional distribution of ground‐motion intensity, rather than intensity at only a single site. Quantifying ground‐motion over a spatially‐distributed region therefore requires information on the correlation between the ground‐motion intensities at different sites during a single event. The focus of the present study is to assess the spatial correlation between ground‐motion spectral accelerations at different periods. Ground motions from eight well‐recorded earthquakes were used to study the spatial correlations. On the basis of obtained empirical correlation estimates, we propose a geostatistics‐based method to formulate a predictive model that is suitable for simulation of spectral accelerations at multiple sites and multiple periods, in the case of crustal earthquakes in active seismic regions. While the calibration of this model and investigation of its implications were somewhat complex, the model itself is very simple to use for making correlation predictions. A user only needs to evaluate a simple equation relying on three sets of coefficients provided here to compute a correlation coefficient for spectral values at two periods and at a specified separation distance. These results may then be used in evaluating the seismic risk of portfolios of structures with differing fundamental periods. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Panta Rhei 2013–2015: global perspectives on hydrology,society and change     

Hilary McMillan  Alberto Montanari  Christophe Cudennec  Hubert Savenije  Heidi Kreibich  Tobias Krueger 《水文科学杂志》2013,58(7):1174-1191

ABSTRACT

In 2013, the International Association of Hydrological Sciences (IAHS) launched the hydrological decade 2013–2022 with the theme “Panta Rhei: Change in Hydrology and Society”. The decade recognizes the urgency of hydrological research to understand and predict the interactions of society and water, to support sustainable water resource use under changing climatic and environmental conditions. This paper reports on the first Panta Rhei biennium 2013–2015, providing a comprehensive resource that describes the scope and direction of Panta Rhei. We bring together the knowledge of all the Panta Rhei working groups, to summarize the most pressing research questions and how the hydrological community is progressing towards those goals. We draw out interconnections between different strands of research, and reflect on the need to take a global view on hydrology in the current era of human impacts and environmental change. Finally, we look back to the six driving science questions identified at the outset of Panta Rhei, to quantify progress towards those aims.