Anticipate response of climate change on coastal risks at regional scale in Aquitaine and Languedoc Roussillon (France)     

C. Vinchon  S. Aubie  Y. Balouin  L. Closset  M. Garcin  D. Idier  C. Mallet 《Ocean & Coastal Management》2009,52(1):47-56

LIFE Environment/RESPONSE project (2003–2006) aimed to evaluate and map, at regional scale, the impact of climate change on coastal risks (erosion and marine flooding), by anticipating the response to regional climatic change scenarios of coastal systems. These are described by their geomorphology, coastal processes, known hazardous events and existing defences. Application on Aquitaine and Languedoc Roussillon regions (France) assesses the likely increase of the coastal risks. In both regions, the weight of geomorphology and settlement development is underlined. The results point out the need for better knowledge on physical resilience capacity of the coast, assets values and vulnerability, and the urge of an integrated management approach of coastal risk, at least at the scale of sedimentary cell.  相似文献   

High-resolution analysis of submarine lobes deposits: Seismic-scale outcrops of the Lauzanier area (SE Alps, France)     

Thierry Mulder  Yannick Callec  Philippe Joseph  Cécile Robin  Tristan Salles  Jonathan Allard  Emmanuelle Ducassou  Brice Ferger  Vincent Hanquiez  Elodie Marchès  Sébastien Zaragosi 《Sedimentary Geology》2010,229(3):160-191

The Lauzanier area represents the northernmost extension of the Annot Sandstone series and contains deposits between 650 and 900 m-thick. This basin was active from upper Bartonian or lower Priabonian to early Rupelian. It is composed of two superposed units separated by a major unconformity. The sediment supply is due to channelled flows coming from the south. Flow processes include mass flow to turbidity currents. The size of the particles and the absence of fine-grained sediment suggest a transport over a short distance. The Lower Unit is made of coarse-grained tabular beds interpreted as non-channelled lobe deposits. The Upper Unit is made of massive conglomerates interpreted as the channelled part of lobes. These lobe deposits settle in a tectonically confined basin according to topographic compensation that occurs from bed scale to unit scale. The abrupt progradation between the lower and the upper unit seems related to a major tectonic uplift in the area. This uplift is also suggested by a change in the petrographic nature of the source and an abrupt coarsening of the transported clasts.This field example allows providing high resolution analysis for depositional sedimentary sequences of terminal lobe deposits in a coarse-grained turbidite system. The outcrop analysis shows the lateral evolution of deposits and the system progradation allows a longitudinal analysis of facies evolution by superposing on the same outcrops the channelled lobe system and the non-channelled lobe system. These results of high-resolution outcrop analysis can be extrapolated to results obtained on sedimentary lobes in recent deep-sea turbidite system that are either restricted to cores, or with a lesser resolution (seismic).  相似文献   

Toward the snowball earth deglaciation…     

Guillaume Le Hir  Yannick Donnadieu  Gerhard Krinner  Gilles Ramstein 《Climate Dynamics》2010,35(2-3):285-297

The current state of knowledge suggests that the Neoproterozoic snowball Earth is far from deglaciation even at 0.2 bars of CO₂. Since understanding the termination of the fully ice-covered state is essential to sustain, or not, the snowball Earth theory, we used an Atmospheric General Climate Model (AGCM) to explore some key factors which could induce deglaciation. After testing the models’ sensitivity to their parameterizations of clouds, CO₂ and snow, we investigated the warming effect caused by a dusty surface, associated with ash release during a mega-volcanic eruption. We found that the snow aging process, its dirtiness and the ash deposition on the snow-free ice are key factors for deglaciation. Our modelling study suggests that, under a CO₂ enriched atmosphere, a dusty snowball Earth could reach the deglaciation threshold.  相似文献   

Is It Possible to Characterize the Geometry of a Real Porous Medium by a Direct Measurement on a Finite Section? 1: The Phase-Retrieval Problem   总被引：1，自引：0，他引：1  

Yannick Anguy  Robert Ehrlich  Cédric Mercet 《Mathematical Geology》2003,35(7):763-788

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High rates of geomorphological processes in a tropical area: the Remparts River case study (Réunion Island, Indian Ocean)     

Manuel Garcin  Blanche Poisson  Richard Pouget 《Geomorphology》2005,67(3-4):335-350

Reunion Island is characterized by rapid landscape evolution resulting from its cyclonic tropical climate. However, local active surface processes are not well understood. The relationships between climatic events, large scale landslides and torrential transport of sediment by the rivers remain unclear. The Remparts River is an appropriate area for studying such geomorphological processes, as it deeply incises the active Piton de la Fournaise volcano. In this study, different approaches are used to analyze the morphological evolution of the river from the sediment production areas to the outlet over the last 40 years. Recurrent events of huge mass wasting occur at Mahavel Cliff, upstream of one of the river tributaries, the most recent producing around 50×10⁶ m³ of sediment in 1965. Combined analyses of the sequence of cyclonic events, major mass wasting events and aerial photography interpretation over the last 40 years led to the proposal of a functional model of river system responses to these events. The river system can be divided into three compartments, each affected by three classes of geomorphological events. The sedimentary response (erosion and/or aggradation) of each compartment to a triggering event, such as cyclonic rainfall and/or seasonal rise of water discharge, is controlled both by the magnitude of the climatic event and by the state of the compartment resulting from previous evolution. A set of five aerial photographs and a satellite image showing the evolution of the studied area during the last 40 years are examined in detail in the light of the functional model. Observations confirm a rapid and complex evolution of the river bed (erosion and aggradation), and provide information about the dynamics of the sediment transfer from the production areas to the ocean. Analysis of two distinct topographic datasets bracketing the last major cyclone Dina in 2002 allows the estimation of the river sediment budget resulting from this event. The net volume of aggraded sediments in the river bed is estimated at around 8×10⁶ m³.With no major collapse event recorded at Mahavel Cliff, sediment transfer due to the flood associated with the 3-day cyclone Dina event is responsible for this significant increase in river bed sediment volume. This quantification shows that several million cubic meters of sediment may take only a few years to spread over more than 5 km downstream. The river bed has now reached its highest elevation since the 1965 landslide, with potential consequences for natural hazards in the area of the outlet at the city of Saint-Joseph.  相似文献   

Sismique marine haute résolution 3D : un nouvel outil de reconnaissance à destination de la communauté scientifique     

Yannick Thomas  Bruno Marsset  Stéphane Didailler  Jean-Pierre Regnault  Sandie Le Conte  Dominique Le Roux  Patrick Farcy  Maurice Magueur  Pascal Viollette  Jacques Herveou  Jean-Charles Guedes  Bernard Jegot  Gilles Gascon  Christian Prud&#x;homme  Hervé Nouze  Estelle Thereau  Isabelle Contrucci  Jean-Paul Foucher 《Comptes Rendus Geoscience》2004,336(6):579-585

This note presents the first results of the development of 3D high-resolution marine seismic method designed for scientific application. A particular attention was paid to the realisation of an operational system to be in agreement with the expected goals in term of acquisition and processing. To cite this article: Y. Thomas et al., C. R. Geoscience 336 (2004).  相似文献   

Sismique très haute résolution 3D : une nouvelle méthode d'imagerie des sols superficielsVery High Resolution 3D seismic: a new imaging tool for sub-bottom profiling     

Tania Marsset  Bruno Marsset  Yannick Thomas  Stéphane Didailler 《Comptes Rendus Geoscience》2002,334(6):403-408

This note presents the first results of the development of a 3D Very High Resolution seismic method. Particular attention was paid to the design of an operational system to be in agreement with the expected goals in term of acquisition and processing. A set of three examples, collected in various geological environments, is presented. To cite this article: T. Marsset et al., C. R. Geoscience 334 (2002) 403–408.  相似文献   

High temperature calorimetric studies of heat of solution of NiO, CuO, La₂O₃, TiO₂, HfO₂ in sodium silicate liquids     

Yannick Linard 《Geochimica et cosmochimica acta》2008,72(2):590-601

The enthalpies of solution of La₂O₃, TiO₂, HfO₂, NiO and CuO were measured in sodium silicate melts at high temperature. When the heat of fusion was available, we derived the corresponding liquid-liquid enthalpies of mixing. These data, combined with previously published work, provide insight into the speciation reactions in sodium silicate melts. The heat of solution of La₂O₃ in these silicate solvents is strongly exothermic and varies little with La₂O₃ concentration. The variation of heat of solution with composition of the liquid reflects the ability of La(III) to perturb the transient silicate framework and compete with other cations for oxygen. The enthalpy of solution of TiO₂ is temperature-dependent and indicates that the formation of Na-O-Si species is favored over Na-O-Ti at low temperature. The speciation reactions can be interpreted in terms of recent spectroscopic studies of titanium-bearing melts which identify a dual role of Ti⁴⁺ as both a network-former end network-modifier. The heats of solution of oxides of transition elements (Ni and Cu) are endothermic, concentration-dependent and reach a maximum with concentration. These indicate a charge balanced substitution which diminishes the network modifying role of Na⁺ by addition of Ni²⁺ or Cu²⁺. The transition metal is believed to be in tetrahedral coordination, charge balanced by the sodium cation in the melts.  相似文献   

MétéEAU Nappes: a real-time water-resource-management tool and its application to a sandy aquifer in a high-demand irrigation context     

Surdyk  Nicolas  Thiéry  Dominique  Nicolas  Jérome  Gutierrez  Alexis  Vigier  Yannick  Mougin  Bruno 《Hydrogeology Journal》2022,30(6):1737-1749

The MétéEAU Nappes water-resource-management tool is presented. It is usable on the aquifer or part-of-aquifer scale for real-time observation of the state of the groundwater resource, and it is already operating in France. This online decision support tool is also able to predict the state of the resource in the short- and mid-terms. The paper explains the use of the tool in a case study in the Authion Valley, in the north-west of France, chosen for its context of tension surrounding the groundwater resource resulting from high volumes of abstraction for irrigation. The results of the simulation highlight the advantages of MétéEAU Nappes as a tool for prediction and simulation of the state of the groundwater resource. The results also show the advantages of this type of tool for water resource management, such as supplying local actors with reliable and real-time observations of the aquifer and providing forecasts to anticipate possible water shortage.

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Evidence for glaciation in the Northern Hemisphere back to 44 Ma from ice-rafted debris in the Greenland Sea     

Aradhna K. Tripati  Robert A. Eagle  Andrew Morton  Julian A. Dowdeswell  Katie L. Atkinson  Yannick Bahé  Caroline F. Dawber  Emma Khadun  Ruth M.H. Shaw  Oliver Shorttle  Lavaniya Thanabalasundaram 《Earth and Planetary Science Letters》2008,265(1-2):112-122

The widely accepted age estimate for the onset of glaciation in the Northern Hemisphere ranges between 2 and 15 million years ago (Ma). However, recent studies indicate the date for glacial onset may be significantly older. We report the presence of ice-rafted debris (IRD) in ～ 44 to 30 Ma sediments from the Greenland Sea, evidence for glaciation in the North Atlantic during the Middle Eocene to Early Oligocene. Detailed sedimentological evidence indicates that glaciers extended to sea level in the region, allowing icebergs to be produced. IRD may have been sourced from tidewater glaciers, small ice caps, and/or a continental ice sheet.  相似文献