Search

International audience

Variations of East Asian summer monsoon (EASM) during the last millennium could help enlighten the monsoonal response to future global warming. Here we present a precisely dated and highly resolved stalagmite δ18O record from the Yongxing Cave, central China. Our new record, combined with a previously published one from the same cave, indicates that the EASM has changed dramatically in association with the global temperature rising. In particular, our record shows that the EASM has intensified during the Medieval Climate Anomaly (MCA) and the Current Warm Period (CWP) but weakened during the Little Ice Age (LIA). We find that the EASM intensity is similar during the MCA and CWP periods in both northern and central China, but relatively stronger during the CWP in southern China. This discrepancy indicates a complicated regional response of the EASM to the anthropogenic forcing. The intensified and weakened EASM during the MCA and LIA matches well with the warm and cold phases of Northern Hemisphere surface air temperature, respectively. This EASM pattern also corresponds well with the rainfall over the tropical Indo-Pacific warm pool. Surprisingly, our record shows a strong association with the North Atlantic climate as well. The intensified (weakened) EASM correlates well with positive (negative) phases of North Atlantic Oscillation. In addition, our record links well with the strong (weak) Atlantic meridional overturning circulation during the MCA (LIA) period. All above-mentioned correlations indicate that the EASM tightly couples with oceanic processes in the tropical Pacific and North Atlantic oceans during the MCA and LIA.

Variations of precipitation, aka the Meiyu rain, in East Asian summer monsoon (EASM) domain during the last millennium could help enlighten the hydrological response to future global warming. Here we present a precisely dated and highly resolved stalagmite δ18O record from the Yongxing Cave, central China. Our new record, combined with a previously published one from the same cave, indicates that the Meiyu rain has changed dramatically in association with the global temperature change. In particular, our record shows that the Meiyu rain has been weakened during the Medieval Climate Anomaly (MCA), but intensified during the Little Ice Age (LIA). During the Current Warm Period (CWP), our record indicates a similar weakening of the Meiyu rain. Furthermore, during the MCA and CWP, our records show that the atmospheric precipitation is similarly wet in northern China and similarly dry in central China, but relatively wet during the CWP in southern China. This spatial discrepancy indicates a complicated localized response of the regional precipitation to the anthropogenic forcing. The weakened (intensified) Meiyu rain during the MCA (LIA) matches well with the warm (cold) phases of Northern Hemisphere surface air temperature. This Meiyu rain pattern also corresponds well with the climatic conditions over the Tropical Indo-Pacific warm pool. On the other hand, our record shows a strong association with the North Atlantic climate as well. The reduced (increased) Meiyu rain correlates well with positive (negative) phases of North Atlantic Oscillation. In addition, our record links well with the strong (weak) Atlantic meridional overturning circulation during the MCA (LIA) period. All above-mentioned localized correspondences and remote teleconnections on decadal to centennial timescales indicate that the Meiyu rain is coupled closely with oceanic processes in the Tropical Pacific and North Atlantic Oceans during the MCA and LIA.

International audience; Known since the 18th century and excavated in particular by Jacques Boucher de Perthes and Joseph Preswitch in the 1840‑1860s, the site of Menchecourt, at Abbeville, played an essential role during the 19th century in the recognition of the coexistence of man and extinct animal species, the foundation of prehistory as a science. Subsequently inaccessible for a long time due to the urbanization of the city since the end of the 19h century and all along the 20th century, the locality was the subject of a preventive archaeological operation carried out by INRAP in 2014 on a zone located in the immediate vicinity of the historical site. The observed stratigraphical sequence is lying on the chalky substratum at an altitude of + 2-3 m asl, i.e. + 14/15 m relative to the maximum incision below the current valley floor. It includes a succession of fluvial and/or fluvio-marine levels covered by a sequence of loessic cover (loess and palaeosols), very close to the one observed in the 19th century. Although the level that delivered lithic pieces attributed to the laminar “Menchecourian” industry defined by G. d’Ault du Mesnil at the end of the 19th century has not been found, several archaeological and paleontological levels that can be linked to the Middle and Lower Paleolithic periods have been identified at the top of the interglacial fluvial sediments of the terrace as well as within the glacial loessic sequence covering it. The palaeontological and geochronological data available make it possible to position the implementation of the sequence within the marine isotopic stages (MIS) 8 to 6 and confirm the interest of organizing in the future a more detailed study of this major archaeological locality of Abbeville Prehistory.; Connu depuis le XVIIIe siècle et exploré notamment par Jacques Boucher de Perthes et Joseph Preswitch dans les années 1840‑1860, le site de Menchecourt à Abbeville a joué au XIXe siècle un rôle essentiel dans la reconnaissance de la coexistence de l’Homme et d’espèces animales disparues, fondement de la Préhistoire en tant que science. Restée par la suite longtemps inaccessible en raison de l’urbanisation de la ville à la fin du xixe siècle et au cours du XXe siècle, la localité a fait l’objet en 2014 d’une opération d’archéologie préventive menée par l’INRAP sur un terrain situé à proximité immédiate du site historique. La séquence stratigraphique mise au jour repose sur le substrat crayeux à une altitude de + 2‑3 m NGF, soit + 14/15 m d’altitude relative par rapport à l’incision maximale sous le fond de vallée actuel. Elle comprend une succession de niveaux fluviatiles et (ou) fluvio-marins recouverts par une séquence de couverture lœssique (loess et paléosols), très proche de celle observée au XIXe siècle. Bien que le niveau ayant livré des pièces attribuées à l’industrie laminaire « menchecourienne » définie par G. d’Ault du Mesnil à la fin du XIXe siècle n’ait pas été retrouvé, plusieurs niveaux archéologiques et paléontologiques rattachables au Paléolithique moyen et inférieur ont été repérés au sommet des sédiments fluviatiles interglaciaires de la terrasse ainsi qu’au sein de la séquence limoneuse glaciaire recouvrant celle-ci. Les données paléontologiques et géochronologiques disponibles permettent de positionner la mise en place de la séquence au sein des stades isotopiques marins (SIM) 8 et 6 et confirment l’intérêt d’organiser dans le futur une étude plus poussée de cette localité majeure de la Préhistoire abbevilloise.

International audience

International audience; Les séquences stratigraphiques de nombreux sites paléolithiques du centre et du sud de l'Italie, formé en contexte fluvio-lacustre et riches en vestiges archéologiques et paléontologiques, ont enregistré de nombreux événements volcaniques. Cette succession d’épisodes détritiques et volcaniques permet la comparaison des chronologies obtenues par la méthode ESR appliquée aux quartz fluviatiles blanchis optiquement, en utilisant les centres Al et Ti, par la méthode ESR/U-Th, appliquée à l'émail dentaire des vestiges paléontologiques, avec le cadre chronologique obtenu par la méthode de datation 40Ar/39Ar, appliquée quant à elle sur des cristaux de feldspaths potassiques.Depuis 2009, plusieurs sites du Pléistocène moyen, comprenant des niveaux volcaniques, fluviatiles et archéologiques ont ainsi été étudiés: Isoletta et Lademagne dans le Latium et Venosa Notarchirico en Basilicate.Les résultats obtenus, qui couvrent la plage de temps compris entre 700 et 350 ka, seront présentés et discutés. Ils indiquent que l'approche multiméthode est utile pour restreindre la chronologie de chaque site et que l'application de chaque méthode a des limitations spécifiques. Malgré ces limitations, nos résultats montrent que le cadre ESR et ESR/U-Th est globalement en accord avec la chronologie 40Ar/39Ar.

International audience

Excavated between 2005 and 2007, the site of Vallparadís (Terrassa, Spain) has given an abundant and diversified fauna associated with a rich Mode 1 industry. In order to complete the chronostratigraphic framework, we performed ESR and combined US-ESR dating applied to quartz grains extracted from sediments and fossil teeth, respectively. The results obtained are very significant, giving a weighted mean ESR age of 0.83 ± 0.13 Ma (2σ) for the reference archaeological level of the site (level 10) and another of 0.79 ± 0.23 Ma (2σ) for the archaeological level 12 of the Vallparadís sequence. These ESR results are in total agreement with the ones derived from biochronology and paleomagnetism. This whole dataset allows the elaboration of a reliable and consistent chronostratigraphic framework which chronologically places Vallparadís site in the late Early Pleistocene period, i.e. within a time range comprised between Jaramillo and Brunhes geomagnetic events. Consequently, as well as Gran Dolina-TD6 and Sima del Elefante- TE9 sites, in Atapuerca, Burgos, Vallparadís can be therefore considered as a key site for the study of early hominid settlements in Europe., Excavado entre 2005 y 2007, el yacimiento de Vallparadís (Terrassa, España) ha aportado una fauna rica y diversa en asociación con un importante conjunto lítico de Modo 1. Con el objetivo de completar el marco cronoestratigráfico, se hicieron dataciones por los métodos de Resonancia Paramagnética Electrónica (Electron Spin Resonance, ESR) y ESR combinada con uranio-torio sobre algunas muestras de granos de cuarzo extraídos de sedimentos y dientes fósiles, respectivamente. Los resultados obtenidos son muy significativos, ofreciendo edades ESR promedias de 0,83 ± 0,13 Ma (2σ) para el nivel arqueológico de referencia del yacimiento (nivel 10) y de 0,79 ± 0,23 Ma (2σ) para el nivel arqueológico 12 de la secuencia de Vallparadís. Dichos resultados por ESR concuerdan con los obtenidos a partir de la biocronología y del paleomagnetismo. El yacimiento de Vallparadís dispone ahora de un marco cronoestratigráfico fiable y coherente, que permite situarlo cronológicamente a finales del Pleistoceno inferior, dentro de un rango temporal comprendido entre los eventos geomagnéticos de Jaramillo y Brunhes. Dicho yacimiento junto a los de Gran Dolina TD-6 y Sima del Elefante TE-9, en Atapuerca, Burgos, se posiciona como un yacimiento clave para el estudio de los primeros poblamientos humanos de Europa.

International audience

L’aven de Romain-la-Roche est l’un des sites paléontologiques majeurs de l’est de la France pour le Pléistocène. Le site, qui correspond au comblement d’une fissure de 7 m de large sur 11 m de haut s’ouvrant dans un substrat calcaire jurassique, a servi de piège naturel pour les grands mammifères et d’abri aux hommes préhistoriques dont la présence est attestée par la découverte de pièces lithiques moustériennes. Fouillé dans les années 1980, le gisement a livré plus de 25000 restes paléontologiques correspondant à une faune variée de grands mammifères, de micro-vertébrés et de mollusques. Une première étude chronologique, réalisée dans les années 1990 par uranium-thorium sur ossements, avait permis de proposer un âge rissien pour le gisement. Cependant, l’un des ossements analysés ayant fonctionné comme un système ouvert vis-à-vis de l’uranium, cette attribution chronologique nécessitait d’être vérifiée. Une nouvelle campagne de datation a donc été entreprise de 2007 à 2010 par la méthode de la résonance de spin électronique combinée à la méthode uranium-thorium (ESR/U-Th). Plusieurs dents issues des collections et provenant des principales couches paléontologiques du remplissage ont ainsi été analysées. Les données isotopiques U-Th de ces échantillons sont, à quelques exceptions près, relativement homogènes et semblent indiquer qu’ils ont tous évolué de façon similaire depuis leur enfouissement. Les résultats de cette étude permettent de dater la partie inférieure du remplissage (couches VI-VII, VIII et IX) de la dernière partie du Riss (stade isotopique 6). Par contre, le niveau supérieur (couche V) a livré des âges incohérents par rapport à la stratigraphie du site et des résultats obtenus pour les niveaux sous-jacents, qui pourraient être expliqués par des phénomènes de migration des éléments radioactifs ou d’une chauffe archéologique éventuelle des ossements. The Romain-la-Roche aven is one of the main palaeontological sites of eastern France for the Pleistocene period. The site, which corresponds to the infilling of a fissure opening into a Jurassic limestone, has acted as a natural trap for great mammals and as a shelter for prehistoric men, as attested by the discovery of Mousterian artefacts. Excavated during the 1980’s, the site has delivered more than 25,000 palaeontological remains corresponding to a diversified fauna including great mammals, micro-vertebrates and molluscs. A previous chronological study, realised during the 1990’s using uranium-series method (U-series) on bones, has allowed the proposal of a Riss age for the site. However, one of the analyzed bones has acted as an open system for uranium migration and its chronological attribution should be verified. A new dating program was therefore performed from 2007 to 2010 combining electron spin resonance and U-series methods (US-ESR). Several teeth selected from collections and issued from the main paleontological layers of the infilling have then been analyzed. Results permit to date the lower part of the sequence (layers VI-VII, VIII and IX) from the last part of the Riss stage (marine isotope stage 6). On the other hand, the upper level (layer V) has not been dated because of probable radioactive element migration.

International audience; The palaeontological site of Venta Micena (Orce, Andalusia, Spain) lies in the eastern sector of the Guadix–Baza basin, one of the best documented areas in Europe for Plio‐Pleistocene biostratigraphy. The combination of biochronological and palaeomagnetic results, combined with the radiometric data obtained for Atapuerca Sima del Elefante, indicated that the Venta Micena stratum was formed between the Jaramillo and Olduvai palaeomagnetic events, most likely between 1.22 and 1.77 Ma. Five fossil teeth from two outcrops (sites A and B) were selected to assess the potential of combined uranium series–electron spin resonance (US‐ESR) dating of Early Pleistocene sites. Although the US‐ESR results of the first outcrop showed a large scatter between the three teeth, the mean age of 1.37 ± 0.24 Ma can be considered a reasonable age estimate for Venta Micena. The mean ESR age of 0.62 ± 0.03 Ma obtained for site B seems to be a severe underestimation when compared with the independent age control. This underestimation is attributed to a relative recent U‐mobilization event that led to some U‐leaching. The results show that any ESR age calculations of old samples are extremely sensitive to variations in the measured 230Th/234U ratios in dental tissues. Although the results demonstrate that ESR can in principle be applied to Early Pleistocene sites, they also reveal the complexity of dating such old teeth. It is necessary to continue research in several directions, such as study of the behaviour of ESR signals in old teeth and understanding recent U‐mobilization processes, to improve the reliability of the combined US‐ESR dating method applied to Early Pleistocene times, a period for which the number of available numerical dating techniques is very limited. Copyright © 2011 John Wiley & Sons, Ltd.