Longshore sediment movements from tracers and models, Praia de Faro, South Portugal
This work aims to improve the knowledge of sediment circulation in the coastal zone, focusing on the quantification of sediment movement due to longshore drift. The studied field site is the Praia de Faro beach on the Peninsula do Anca˜o in Algarve (Portugal), which is located on the updrift coast of the Barra Nova tidal inlet. The main objective of the study was to quantify the sediment transport rate that will enter in the inlet system. Measurements were undertaken during low hydrodynamic conditions prevailing in this area and permitted to estimate a longshore transport rate of 2.6–4.2 m/s, consistent with other transport estimations in Algarve. Four theoretical models for longshore transport rate calculation were confronted to tracer results to choose a extrapolation tool. KAMPHUIS (1991) formula appeared to be the more appropriate in this area. It was used to extrapolate the results in order to be compared to the observed morphological evolution. The calculated short term sediment flux (10500 m3/ month) corresponds to the accretion on the updrift swash platform of the Barra Nova tidal inlet and is thus considered to be the contribution of the adjacent coast to this system. Moreover, the estimated longshore transport rate permit us to predict a spit progradation of 60–70 m/year. This result is consistent with the observed migration rate of the Barra Nova inlet during the last 25 years. This study shows that, with a good knowledge of the environmental context, sediment fluxes obtained by sand tracers are accurate enough to estimate the long term longshore transport and long term morphological response of a stretch of shoreline.
(Journal of Coastal Research. vol. 21, n° 0749-0208, pp. 146-156, 01/01/2005)
BRGM, BIAF, UA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Facteurs de contrôle de la sédimentation organique profonde associée au système d'upwelling du courant du Benguela durant le pleistocène.
La marge Sud-Est Atlantique a été le siège d'une accumulation très importante de carbone organique durant les derniers cycles climatiques : les teneurs y sont parmi les plus élevées du monde pour des sédiments océaniques (de 5 à 18-20% à 1000 m de profondeur, de 0,5% à 8% à 3500 m). Ces accumulations sont liées à l'intense activité des cellules d'upwelling associées au système du Courant du Benguela, elles-mêmes fonctions de l'intensité des alizés circulant le long de la côte. Nous avons, pour ce travail, étudié une section du forage ODP 175-1084A prélevée à bord du DV JOIDES Resolution entre août et octobre 1997 au large de la Namibie. L'objectif de cette étude est de comprendre le fonctionnement du site de haute productivité de Lüderitz durant le Pléistocène (autour de 1,1 Ma). La période étudiée correspond à un stade où le courant du Benguela est passé d'un système frontalier à un système d'upwelling côtier intense, tel qu'il existe aujourd'hui. Le site de Lüderitz a été choisi car il est associé aux taux d'accumulation organique les plus importants, et permet donc une étude globale des processus sédimentaires associés aux différents contextes atmosphériques et océanographiques existant à cette époque. Nous avons réalisé cette étude en déterminant, entre autres, les concentrations en COT, carbonates et silice biogène, dans le but d'estimer les variations de paléoproductivité, les concentrations en quartz, kaolinite et smectite pour estimer les variations des flux détritiques éoliens. Ce travail a été complétée par une étude de biomarqueurs spécifiques des producteurs siliceux (stérols), carbonatés (alcénones) et des végétaux supérieurs (n-alcanes).
(pp. 7p., 25/08/2026)
MNHN, UPMC, CNRS, ISTO, INSU - CNRS, UO, CNRS, LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, UMich
Les dépôts de lobes turbiditiques du lac du Lauzanier (Ubaye, France)
(25/08/2026)
GR, UR, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A new wave-breaking parametrization for Boussinesq-type equations
(pp. 53, 25/08/2026)
LEGI, UJF, Grenoble INP, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Lower Devonian vertebrates, arthropods and brachiopods from northern Vietnam
Additional vertebrates and ostracods from the bituminous shale of the Khao Loc Formation at Tong Vai, Ha Giang Province, northern Vietnam, corroborate its correlation with the upper part of the Xishancun (Xiaxishancun) Formation and the lower part of the Xitun and Lianhuashan formations of South China, and its Middle to Late Lochkovian age. The variations in morphology and ornamentation of the galeaspid Polybranchiaspis liaojaoshanensis from Tong Vai are discussed and regarded as possibly size and growth-related. A new acanthothoracid placoderm with a very deep dorsal process is described from Tong Vai and the specific distinction between the antiarchs Minicrania lissa from TongVai and M. lirouyii fromYunnan is supported by additional characters. Petalichthyid placoderms are recorded from this locality for the first time, and the skull of a juvenile youngolepidid sarcopterygian is described. Eurypterid fragments and a phyllocarid crustacean are also recorded from the Khao Loc Formation. A new species of the chonetid brachiopod genus Tulynetes, endemic to northern Vietnam, is described from the Pragian Mia Le Formation at Cu Le, Bac Kan Province, a new locality which yields a large diversity of taxa with outstanding preservation.
(Geobios. vol. 38, n° 0016-6995, pp. 533-551, 25/08/2026)
LDO, INSU - CNRS, UBO EPE, CNRS, MNHN, UPMC, CNRS, NHM, VNU, PEPS, UCBL, INSU - CNRS, CNRS, CAS
Turbulence measurements in fluid mud layers of a macrotidal estuary
(25/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGI, UJF, Grenoble INP, CNRS, LTHE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, IRD, INSU - CNRS, INPG, CNRS
Deglaciation and volcano-seismic activity in Northern Iceland : Holocene and Early Eemian
(Geodinamica Acta. vol. 18 (1), n° 0985-3111, pp. 81-100, 25/08/2026)
PBDS, INSU - CNRS, CNRS, LPGN, UN, CNRS, GR, UR, INSU - CNRS, CNRS, MNHN, UPMC, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
A slab-on-slab model for the Flims rockslide (Swiss Alps)
(Canadian Geotechnical Journal, n° 0008-3674, pp. 587-600, 25/08/2026)
GEOSCIENCES, PSL, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UP1, LGP, UP1, UPEC UP12, CNRS
The biogeography of major diatom taxa in Southern Ocean sediments
Diatoms from 228 Southern Ocean core-top sediment samples were examined to determine the geographic distributions of 32 major diatom species/taxa preserved in the sediments of three zonally-distinct regions; Sea Ice, Open Ocean and the Tropical/Subtropical. In the first of three papers, 14 species/taxa occurring in the region where sea ice covers the ocean surface on an annual basis are geographically documented. Comparisons are drawn between the diatom abundances on the sea floor, sea ice parameters (annual duration and concentration in February and September) and February sea-surface temperature. Such parameters are commonly used in reconstructing past oceanographic conditions in the Sea Ice and Open Ocean zones. Analysis of the geographic patterns and sea-surface parameter correlations reveals species-specific distributions regulated primarily by sea ice coverage and sea-surface temperature, which support the use of diatom remains for the estimation of these past sea-surface environmental parameters. Comparison with reliable accounts of the 14 species from the sediments or plankton also provides the first glimpses into species-specific ecology and habitat linkages.
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 223, n° 0031-0182, pp. 93-126, 25/08/2026)
UTAS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Morphodynamics of nearshore rhythmic sandbars in a mixed-energy environment (SW France): 2. Physical forcing analysis
The morphology and migration of rhythmic intertidal ridge and runnel systems, and subtidal crescentic bars that border the southwest coast of France were characterized using in situ surveys and maps obtained by remote-sensing methods. The period from 1986 to 2000 was investigated. A total of 35 km of coast was mapped. This data set shows several specificities, the origin of which are examined in the present report using hydrodynamic data. A complete analysis of the influence of wave climate on both the shape and the movements of these rhythmic sedimentary patterns was performed. In addition, SWAN and MORPHODYN-coupled numerical models were used to provide quantification of both wave breaking and longshore currents for wave parameters that were representative of the mean values and of the energetic conditions. This study demonstrated the short time response of intertidal systems to the wave forcing. When the offshore significant wave height ( Hs) was lower than 2.5 m, regular coastal ridge and runnel systems developed in the intertidal zone and migrated in the longshore-drift direction at a rate of 1.7-3.1 m day -1. By contrast, the ridge and runnel system morphology abruptly changed when the Hs exceeded 2.5 m, and after the storm, the typical ridge and runnel rhythmic topography was recovered within 5-9 days. The crescentic bars, which had a convex seaward shape, were affected by waves with Hs values greater than 3 m (slightly less for short waves). Depending on the wave orientation, the crescentic bars moved in the longshore-drift direction at a rate that reached 1 m day -1. The data suggested a slight negative correlation between the mean alongshore length of the crescentic bar and the mean Hs. Finally, it seemed that increasing the wave obliquity with respect to the coast resulted in the flattening of the crescentic bars. Thus, coupling Spot and in situ mapping to hydrodynamic records allow the characterization of coastal morphology and dynamics, with time and space samplings that are particularly well adapted to the little studied alongshore morphodynamics. This approach should improve the difficult parameterization of morphodynamic models in high-energy environments.
(Estuarine, Coastal and Shelf Science. vol. 65, n° 0272-7714, pp. 449-462, 25/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS