Le phénomène d'ensablement qui touche le port du Pointeau sur la commune de Saint-Brévin-les-Pins... more Le phénomène d'ensablement qui touche le port du Pointeau sur la commune de Saint-Brévin-les-Pins s'est considérablement accentué au fil du temps par l'action conjointe des courants littoraux et de l'action anthropique. La construction des digues du ports a modifié le transit sédimentaire et conduit à la formation de barre sableuses à l'intérieur du port du Pointeau. L'utilisation de dalles lidar du port du Pointeau de 2017 à 2021 a permis de visualiser clairement cette évolution de la plage du port. Dans un second temps, une analyse granulométrique, complétée par une analyse géochimique par spectrométrie à fluorescence X (XRF) a été réalisée sur plusieurs échantillons. Cette méthodologie a permis de mieux comprendre la dynamique sédimentaire de cet environnement et de préciser les sources d'origine des échantillons de sables observés. Les résultats obtenus en granulométrie et confirmés par la géochimie montrent une différence nette d'origine pour les échantillons laissant sous-entendre une double origine pour ce sable de la plage du Pointeau.
Cette publication etablit une syntheese de nos connaissances sur la cadre de geographie physique ... more Cette publication etablit une syntheese de nos connaissances sur la cadre de geographie physique dans la zone du Coutireau Islais ( zone comprise entre Noirmoutier, l´Ile de´Yeu et Saint-Gilles-Croix-de-Vie). Elle montre que le Coureau Islais forme un systeme sedimentaire a part entiere, fortement influence par la presence de l´Ile d´Yeu, ce qui lui confere des caracteristiques morphodynamiques bien differentes du reste de la bande littorale vendeenne. La synthese realisee met en evidence des lacunes dans nos connaissances des processus hydro-sedimentaires qui regssent les flux sedimentaires dans cette zone et influencent l´evolution du trait de cote aussi bien sur l´^ILE D´Yeu que le long des Pays de Monts. De la meme facon, les transferts le long de continuum terre-mer insullaire sont encore trop peu etudies pour etre compris et modelises. Compte-tenu de la mise en oeuvre prochaine de diverses infrastructures ( parc eolien,exploitation de granulats marins(, il semble a present ind...
In aquatic environments, the benthic water column exhibits strong concentration gradients of vari... more In aquatic environments, the benthic water column exhibits strong concentration gradients of various substances. They result from transfers and chemical reactions that may occur both within this layer, and at the sediment–water interface (SWI). Characterization of these gradients yields important information for the quantification of such processes and transfers. However, it is difficult to actually sample these gradients in the field, since turbulence decreases their vertical scale. This article describes a sampler designed to collect simultaneously 16 discrete water column samples at a centimeter‐scale vertical resolution. This small device (40 × 40 × 60 cm) is reliable, safe to handle, and easily deployed from a small boat using a cable or a Scuba diver. It is made of materials compatible with trace element and dissolved gases work, and simultaneously draws samples from various heights above the SWI into 60 mL syringes. The altitude of the sample inlets is field‐adjustable. Sampl...
The system of terraces of the river Seine is very complex on the continent from the source in eas... more The system of terraces of the river Seine is very complex on the continent from the source in eastern France to Le Havre, as well as on its immerged part, the English Channel, where there is a confluence with the palaeovalley of the river Somme and the Northern ...
HAL (Le Centre pour la Communication Scientifique Directe), Jul 18, 2022
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Sediment core KV14bis was retrieved from the Fosse du Croisic, a Loire River incised paleovalley ... more Sediment core KV14bis was retrieved from the Fosse du Croisic, a Loire River incised paleovalley located in the inner shelf of the Bay of Biscay. This core (5.4 m length) covers the past 2.6 cal kyr BP with high sedimentation rate. A multiproxy approach (X-ray imagery, XRF data, grain size analyses, and benthic foraminiferal assemblages) was applied in order to reconstruct the hydrological regime of the Loire River during the late Holocene. This hydrological regime was further linked to climate forcing (e.g. solar activity, North Atlantic Oscillation-NAO) and human activity. Our data describe a succession of several dry/humid periods. The humid periods are centered on ~2.2, 1.3, and 0.5 cal kyr BP and are characterized by high terrigenous flux, fine silty sedimentation, relatively high organic carbon content and high proportions of the epiphytic foraminiferal species Planorbulina mediterranensis. This species was probably brought to the study site by the Loire river plume, attached on floating algae. The dry periods are centered on ~2.5, 1.5, 1.2 cal kyr BP and 1900 AD and are characterized by low terrigenous input, and high carbonate content due to abundant shell debris. During periods of low river runoff, deposition of a sand-particle population (grain size ~ 200 µm) could indicate increased storminess. This latter may have remobilized sediments from shallower depths during these generally dry periods on the continent. The overall coherence of our results with several European continental records supports a pluri-centennial scale regional climate control of humidity and storminess resembling that of the NAO. Spectral analyses emphasized a possible additional control of solar activity. Through deforestation and soil erosion, early human impact was also probably superimposed on this climatic forcing.
Please note that this is an author-produced PDF of an article accepted for publication following ... more Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.
Le phénomène d'ensablement qui touche le port du Pointeau sur la commune de Saint-Brévin-les-Pins... more Le phénomène d'ensablement qui touche le port du Pointeau sur la commune de Saint-Brévin-les-Pins s'est considérablement accentué au fil du temps par l'action conjointe des courants littoraux et de l'action anthropique. La construction des digues du ports a modifié le transit sédimentaire et conduit à la formation de barre sableuses à l'intérieur du port du Pointeau. L'utilisation de dalles lidar du port du Pointeau de 2017 à 2021 a permis de visualiser clairement cette évolution de la plage du port. Dans un second temps, une analyse granulométrique, complétée par une analyse géochimique par spectrométrie à fluorescence X (XRF) a été réalisée sur plusieurs échantillons. Cette méthodologie a permis de mieux comprendre la dynamique sédimentaire de cet environnement et de préciser les sources d'origine des échantillons de sables observés. Les résultats obtenus en granulométrie et confirmés par la géochimie montrent une différence nette d'origine pour les échantillons laissant sous-entendre une double origine pour ce sable de la plage du Pointeau.
Cette publication etablit une syntheese de nos connaissances sur la cadre de geographie physique ... more Cette publication etablit une syntheese de nos connaissances sur la cadre de geographie physique dans la zone du Coutireau Islais ( zone comprise entre Noirmoutier, l´Ile de´Yeu et Saint-Gilles-Croix-de-Vie). Elle montre que le Coureau Islais forme un systeme sedimentaire a part entiere, fortement influence par la presence de l´Ile d´Yeu, ce qui lui confere des caracteristiques morphodynamiques bien differentes du reste de la bande littorale vendeenne. La synthese realisee met en evidence des lacunes dans nos connaissances des processus hydro-sedimentaires qui regssent les flux sedimentaires dans cette zone et influencent l´evolution du trait de cote aussi bien sur l´^ILE D´Yeu que le long des Pays de Monts. De la meme facon, les transferts le long de continuum terre-mer insullaire sont encore trop peu etudies pour etre compris et modelises. Compte-tenu de la mise en oeuvre prochaine de diverses infrastructures ( parc eolien,exploitation de granulats marins(, il semble a present ind...
In aquatic environments, the benthic water column exhibits strong concentration gradients of vari... more In aquatic environments, the benthic water column exhibits strong concentration gradients of various substances. They result from transfers and chemical reactions that may occur both within this layer, and at the sediment–water interface (SWI). Characterization of these gradients yields important information for the quantification of such processes and transfers. However, it is difficult to actually sample these gradients in the field, since turbulence decreases their vertical scale. This article describes a sampler designed to collect simultaneously 16 discrete water column samples at a centimeter‐scale vertical resolution. This small device (40 × 40 × 60 cm) is reliable, safe to handle, and easily deployed from a small boat using a cable or a Scuba diver. It is made of materials compatible with trace element and dissolved gases work, and simultaneously draws samples from various heights above the SWI into 60 mL syringes. The altitude of the sample inlets is field‐adjustable. Sampl...
The system of terraces of the river Seine is very complex on the continent from the source in eas... more The system of terraces of the river Seine is very complex on the continent from the source in eastern France to Le Havre, as well as on its immerged part, the English Channel, where there is a confluence with the palaeovalley of the river Somme and the Northern ...
HAL (Le Centre pour la Communication Scientifique Directe), Jul 18, 2022
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Sediment core KV14bis was retrieved from the Fosse du Croisic, a Loire River incised paleovalley ... more Sediment core KV14bis was retrieved from the Fosse du Croisic, a Loire River incised paleovalley located in the inner shelf of the Bay of Biscay. This core (5.4 m length) covers the past 2.6 cal kyr BP with high sedimentation rate. A multiproxy approach (X-ray imagery, XRF data, grain size analyses, and benthic foraminiferal assemblages) was applied in order to reconstruct the hydrological regime of the Loire River during the late Holocene. This hydrological regime was further linked to climate forcing (e.g. solar activity, North Atlantic Oscillation-NAO) and human activity. Our data describe a succession of several dry/humid periods. The humid periods are centered on ~2.2, 1.3, and 0.5 cal kyr BP and are characterized by high terrigenous flux, fine silty sedimentation, relatively high organic carbon content and high proportions of the epiphytic foraminiferal species Planorbulina mediterranensis. This species was probably brought to the study site by the Loire river plume, attached on floating algae. The dry periods are centered on ~2.5, 1.5, 1.2 cal kyr BP and 1900 AD and are characterized by low terrigenous input, and high carbonate content due to abundant shell debris. During periods of low river runoff, deposition of a sand-particle population (grain size ~ 200 µm) could indicate increased storminess. This latter may have remobilized sediments from shallower depths during these generally dry periods on the continent. The overall coherence of our results with several European continental records supports a pluri-centennial scale regional climate control of humidity and storminess resembling that of the NAO. Spectral analyses emphasized a possible additional control of solar activity. Through deforestation and soil erosion, early human impact was also probably superimposed on this climatic forcing.
Please note that this is an author-produced PDF of an article accepted for publication following ... more Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.
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