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Motility is a fundamental survival strategy of bacteria to navigate porous environments. Swimming cells thrive in quiescent wetlands and sediments at the bottom of the marine water column, where they mediate many essential biogeochemical processes. While swimming motility in bulk fluid is now well established, a comprehensive understanding of the mechanisms regulating self-transport in the confined interstices of porous media is lacking, and determining the interactions between cells and surfaces of the solid matrix becomes paramount. Here, we precisely track the movement of bacteria (\emph{Magnetococcus marinus}) through a series of microfluidic porous media with broadly varying geometries and show that cell motility results in a succession of scattering events from the porous microstructure. Order or disorder can impact the cells' motility over short ranges, but we directly demonstrate that their large-scale transport properties are regulated by the cutoff of their persistent swimming, which is dictated primarily by the porosity and scale of the porous geometry. The effective mean free path is established as the key geometrical parameter controlling transport, and along with with minimal knowledge of cell swimming motility and surface scattering properties, we implement a theoretical model that universally predicts the effective diffusion of cells for the geometries studied here. These results are an important step toward predicting the physical ecology of swimming cells in quiescent porous media and understanding their role in environmental and health hazards in stagnant water., 12 pages, 4 figures

International audience; Successive experimental images of a blob of small non-diffusive tracers..

The Rochechouart impact structure, located in the western part of the Massif Central in France, has been suggested to be one of the largest impact structures in western Europe. Various age datings have placed the event in a span from the Late Triassic to the Early Jurassic, but the most recent works favour a Late Triassic age. Very little is known about the target environment at the time and location of the impact event. Seemingly coeval, potential tsunamites along palaeoshorelines of the sea that covered parts of continental Europe at the time have been suggested to be related to the impact event and may indicate a marine target setting. Here we apply the method of visual line-logging of the graded suevite in the Chassenon SC2 drill core. This method has previously been used to investigate the depositional environment of similar deposits in several marine target impact craters. It allowed us to compare the deposits at these craters with those at Rochechouart, and in this way not only confirm the marine target setting, but also estimate the target water depth to be ∼200 m. Altogether, our results indicate a palaeogeographic target setting in a newly opened seaway connecting the Paris Basin with the Aquitaine Basin, which may indicate an age of impact at the younger end of the hitherto suggested age-span, i.e. in the late Rhaetian – Early Jurassic.

International audience; Iron (Fe) oxyhydroxides are major phases that may control the cerium (Ce) behavior in the Earth's Critical Zone. However, understanding Ce behavior with Fe oxyhydroxides remains uncompleted. Especially, if thermodynamic calculations suggest that Fe(III) is not a sufficiently strong oxidant, several studies reported the presence of Ce(IV) onto Fe oxyhydroxides. In this study, multiple approaches, including modeling and X-ray absorption spectroscopy, deciphered the driving forces of Ce(III) oxidation to Ce(IV) onto goethite. Results showed that oxidized Ce occurred onto goethite with a Ce(III)/Ce(IV) ratio depending on the Ce concentration in the solution ([Ce]tot). The percentage of Ce(IV) onto goethite ranged from 20% to 50%, linearly increasing with [Ce]tot. Comparable observation with a redox-inert Al-hydroxide (gibbsite), allowed to rule out the importance of Fe(III) redox reactivity as the main driver of Ce(III) oxidation. Instead, thermodynamic calculations suggested that surface precipitation of Ce(IV)-hydroxides, whose formation is favored with increasing [Ce]tot, was an important driving force of the redox reaction. Because the goethite surface seemed to stabilize more strongly Ce(IV) than Ce(III) surface species than does gibbsite, differences in binding mechanisms of Ce(III) and Ce(IV) onto different mineral surfaces have been suggested to play a role on Ce redox speciation.

International audience; This chapter provides an understanding of the natural and induced formation damages (FDs) during and after gas injection into oil reservoirs for enhanced oil recovery (EOR) purposes. Several experimental and theoretical investigations, a limited number of pilot practices, and some cases of field applications have shown that the injection of gas can considerably increase oil recovery, at both the microscopic and macroscopic levels. However, the economic production of oil reservoirs after implementing EOR methods has been challenged by damages and resulting reservoir production losses. Therefore, in this chapter, attempts were made to present a brief description about dominant mechanisms of FD while applying gas-based EOR techniques in oil reservoirs. Furthermore, an explanation of techniques to mitigate FDs during EOR approaches are presented.

International audience; Iron is an essential element for all living organisms, playing a major role in plant biochemistry as a redox catalyst based on iron redox properties. Iron is the fourth most abundant element of the Earth’s crust, but its uptake by plants is complex because it is often in insoluble forms that are not easily accessible for plants to use. The physical and chemical speciation of iron, as well as rhizosphere activity, are key factors controlling the bioavailability of Fe. Iron can be under reduced (Fe2+) or oxidized (Fe3+) ionic forms, adsorbed onto mineral surfaces, forming complexes with organic molecules, precipitated to form poorly crystalline hydroxides to highly crystalline iron oxides, or included in crystalline Fe-rich mineral phases. Plants must thus adapt to a complex and changing iron environment, and their response is finely regulated by multiple signaling pathways initiated by a diversity of stimulus perceptions. Higher plants possess two separate strategies to uptake iron from rhizosphere soil: the chelation strategy and the reduction strategy in grass and non-grass plants, respectively. Molecular actors involved in iron uptake and mobilization through the plant have been characterized for both strategies. All these processes that contribute to iron homeostasis in plants are highly regulated in response to iron availability by downstream signaling responses, some of which are characteristic signaling signatures of iron dynamics, while others are shared with other environmental stimuli. Recent research has thus revealed key transcription factors, cis-acting elements, post-translational regulators, and other molecular mechanisms controlling these genes or their encoded proteins in response to iron availability. In addition, the most recent research is increasingly highlighting the crosstalk between iron homeostasis and nutrient response regulation. These regulatory processes help to avoid plant iron concentrations building up to potential cell functioning disruptions that could adversely affect plant fitness. Indeed, when iron is in excess in the plant, it can lead to the production and accumulation of dangerous reactive oxygen species and free radicals (H2O2, HO•, O2•−, HO•2) that can cause considerable damages to most cellular components. To cope with iron oxidative stress, plants have developed defense systems involving the complementary action of antioxidant enzymes and molecular antioxidants, safe iron-storage mechanisms, and appropriate morphological adaptations.

International audience; In the current study, contrasting growth behaviour of redox sensitive Fe0 nanoparticles (nZVI)was observed on different clay surfaces i.e., 1:1 non-swelling kaolinite (K-nZVI) and 2:1swelling bentonite (B-nZVI). Osmotic swelling of bentonite led to Fe0 nucleation and growthof 5-7 nm size particles in the broadened interlayer spaces. B-nZVI had negative zeta potentialdue to the domination of the surface charge of bentonite clay. Whereas kaolinite has showndominant surface growth of nZVI particles (>24.8±7.4 nm) and positive zeta potential,suggesting domination of Fe0 nanoparticles (nZVI) characteristics. This surface-dependentvariation led to higher and faster removal of oxy-anions with K-nZVI, i.e., chromium andarsenic (87.5 and 157.35 mg/g) than B-nZVI (18.4 and 86.9 mg/g). In comparison, B-nZVI hasshown higher sorption of cations i.e., nickel and cadmium (36 mg/g and 46 mg/g) than K-nZVI(25 and 27 mg/g). XPS and pXRD analysis of reaction precipitates confirmed reductivesorption of chromium, co-precipitation/ complexation of arsenic, electrostatic attraction andcomplexation of nickel and cadmium as major removal mechanisms. Drastically higher totalcontaminant sorption capacities of B-nZVI (327 mg/g) and K-nZVI (372 mg/g) in multicontaminant(Cr+As+Ni+Cd) solutions than individual capacities in mono-ionic solutions wasdue to co-operative effects and newer sites induced via sorption and redox-transformation ofother ionic species. K-nZVI removed chromium and arsenic to below drinking waterpermissible limits whereas B-nZVI succeeded in separating nickel and cadmium to drinkablelevels in groundwater, freshwater, river water, and wastewater samples, emphasizing theirapplicability in high cationic—low anionic and low cationic-higher anionic speciescontaminated waters, respectively.

Did Neanderthal produce a bone industry? The recent discovery of a large bone tool assemblage at the Neanderthal site of Chagyrskaya (Altai, Siberia, Russia) and the increasing discoveries of isolated finds of bone tools in various Mousterian sites across Eurasia stimulate the debate. Assuming that the isolate finds may be the tip of the iceberg and that the Siberian occurrence did not result from a local adaptation of easternmost Neanderthals, we looked for evidence of a similar industry in the Western side of their spread area. We assessed the bone tool potential of the Quina bone-bed level currently under excavation at chez Pinaud site (Jonzac, Charente-Maritime, France) and found as many bone tools as flint ones: not only the well-known retouchers but also beveled tools, retouched artifacts and a smooth-ended rib. Their diversity opens a window on a range of activities not expected in a butchering site and not documented by the flint tools, all involved in the carcass processing. The re-use of 20% of the bone blanks, which are mainly from large ungulates among faunal remains largely dominated by reindeer, raises the question of blank procurement and management. From the Altai to the Atlantic shore, through a multitude of sites where only a few objects have been reported so far, evidence of a Neanderthal bone industry is emerging which provides new insights on Middle Paleolithic subsistence strategies.

International audience; Concentration fields of solutes in porous media often exhibit large fluctuations, driven by physical and chemical heterogeneity from the pore to the Darcy scale. For many applications, ranging from reactive transport modeling to toxicology, the knowledge of mean concentrations is not sufficient, and quantifying concentration variability is necessary. The probability density function Highlights • We introduce a general framework quantifying the link between concentration PDFs and spatial concentration profiles. • We derive a dynamical equation for the evolution of the concentration PDF under diffusion and nonlinear reaction in 1D. • We derive analytical predictions for the concentration PDF and its moments using a weakcoupling approximation.

The presence of nanoplastics in the environment has been proven. There is now an urgent need to determine how nanoplastics behave in the environment and to assess the risks they may pose. Here, we examine nanoplastic homo- and heteroaggregation, with a focus on environmentally relevant nanoplastic particle models. We made a systematic analysis of experimental studies, and ranked the environmental relevance of 377 different solution chemistries, and 163 different nanoplastic particle models. Since polymer latex spheres are not environmentally relevant (due to their monodisperse size, spherical shape, and smooth surface), their aggregation behavior in natural conditions is not transferable to nanoplastics. A few recent studies suggest that nanoplastic particle models that more closely mimic incidentally produced nanoplastics follow different homoaggregation pathways than latex sphere particle models. However, heteroaggregation of environmentally relevant nanoplastic particle models has seldom been studied. Despite this knowledge gap, the current evidence suggests that nanoplastics may be more sensitive to heteroaggregation than previously expected. We therefore provide an updated hypothesis about the likely environmental fate of nanoplastics. Our review demonstrates that it is essential to use environmentally relevant nanoplastic particle models, such as those produced with top-down methods, to avoid biased interpretations of the fate and impact of nanoplastics. Finally, it will be necessary to determine how the heteroaggregation kinetics of nanoplastics impact their settling rate to truly understand nanoplastics' fate and effect in the environment., NanoImpact, 29, ISSN:2452-0748

The evolution of depositional environments in the Late Pennsylvanian-early Permian of the Paradox Basin in Utah, USA, is investigated through detailed sedimentological and high-resolution sequence stratigraphic analyses, in order to define a model of landscape evolution, to discuss the stratigraphic model, and to evaluate the significance of the cyclicity in the paleoclimatic context. Forty high-resolution cycles integrated in 15 minor and two major cycles are observed for the first time throughout the Late Pennsylvanian-early Permian units. A-three steps landscape evolution is recognized. First, the lower Cutler beds, mainly corresponded to a marine environment, with longshore bar, subtidal, tidal, mouth-bar, and with locally fluvial deposits. The upper part of the lower Cutler beds also contains an aeolian dune. Second, the Cedar Mesa Sandstone, corresponded to broad erg deposits which are present across the entire study area, whereas longshore bar, subtidal, mouth-bar, and some fluvial deposits are mainly preserved in the northern part of the studied area. Third, the Organ Rock Formation records decreasing aeolian dune field preservation. To the south, the aeolian environments are interbedded with shoreface deposits, whereas to the north, fluvial deposits with some mouth-bars are more developed. Semi-arid climatic conditions persisted, as indicated by the presence of calcretes. Everywhere in these three steps, root traces within sandstone bars indicate that a soil was once present above the sand dunes. This new model of landscape evolution documents complex interactions between aeolian, fluvial and marine environments within the entire Permian succession of the Paradox Basin. High-resolution stratigraphic analyses allow to discuss the significance of the cyclicity in a scenario that take into consideration sea-level variation in the Late Paleozoic Ice Age paleoclimatic context. This Late Pennsylvanian to early Permian succession reflects both relative sea-level fluctuations and the variability of sediment supply.

International audience; Formed through oxidation of underlying primary sulfide- and/or oxide-bearing mineralization, gossans remain a major metallotect for mineral exploration. The identification of gossans within arid regions with ferruginous regolith of different origins is not easy and requires a good knowledge of these superficial red indurated formations on a regional scale. Following this approach, we studied some ferruginous cuirasses in the Khat Oummat Elbid (KOB) region of Inchiri in Mauritania, a region actively prospected for gold and copper in particular. The KOB zone belongs to the orogenic segment of the northern Mauritanides. Two hills with a quartzite basement and capped with ferruginous duricrust were selected for this study. The good outcrop quality made it possible to study the basement, to realize logs across the duricruts and to sample for petrographic, mineralogical (optical microscopy, SEM, DRX) and geochemical (multi-elementary total rock) analyses. The duricrusts are ferricretes in the strict sense with no direct link to the development of lateritic profiles. The quarzitic basement contributes only by producing a coarse clastic fraction at the base of the ferricretes. The cement of the ferricretes is goethitic at the base in between the quartzite clasts while the top is marked by very fine grain sizes and dominant authigenic processes (nodules and pisolites with cortex of goethite and hematite). From the base to the top of the ferricretes, rounded ilmenite grains accompanied by small quartz grains suggest aeolian transport “sprinkling” this material from external sources. These ferricretes are therefore characterized by significant mechanical and chemical allochthonies, the source of Fe in solution such as grains of ilmenite being difficult to trace with certainty in this region. The comparison with average contents of major and trace elements of gossans, lateritic cuirasses and bog ore shows that whole rock geochemistry can be used to discriminate KOB ferricretes from gossans at first-order, but that databases should be implemented with analyzes of gossans developing above iron-oxides-copper-gold deposits such as those exploited in Inchiri ( e.g. the Guelb-Moghrein deposit, near Akjoujt).; -Les chapeaux de fer (ou gossans) développés à l'aplomb d'une minéralisation sulfurée et/ou oxydée primaire restent un métallotecte majeur pour l'exploration minière. L'identification de gossans au sein de régions arides à régolithe ferrugineux de différentes origines n'est pas aisée et suppose une bonne connaissance de ces formations superficielles indurées rouges à l'échelle régionale. En s'inscrivant dans cette démarche, nous avons étudié certaines cuirasses ferrugineuses de la région de Khat Oummat Elbid (KOB) d'Inchiri en Mauritanie, région activement prospectée pour l'or et le cuivre en particulier. La zone de KOB appartient au segment orogénique des Mauritanides septentrionales. Deux collines à socle de quartzite et coiffées de cuirasses ferrugineuses ont été sélectionnées pour cette étude. Les campagnes de terrain ont permis d'étudier le socle, de lever des logs dans les cuirasses et d'échantillonner pour des analyses pétrographiques, minéralogiques (microscopie optique, MEB, DRX) et géochimiques (multi-élémentaire roches totales). Il apparaît que les cuirasses étudiées sont des ferricrètes au sens strict sans lien direct avec le développement de profils latéritiques. Le socle quartzitique contribue uniquement en produisant une fraction clastique grossière à la base des ferricrètes. Le ciment des ferricrètes est goethitique à la base entre les clastes de quartzite tandis que le sommet est marqué par des granulométries très fines et des processus authigéniques dominants (nodules et pisolithes à cortex de goethite et hématite). De la base au sommet des ferricrètes, des grains d'ilménite arrondis accompagnés de grains de quartz de petite taille suggèrent un transport éolien « saupoudrant » ce matériel depuis des sources externes. Ces ferricrètes sont donc caractérisés par des allochtonies mécaniques et chimiques importantes, la source du Fe en solution comme des grains d'ilménite étant difficilement traçable avec certitude dans cette région. La comparaison avec des teneurs moyennes en éléments majeurs et traces de gossans, cuirasses latéritiques et minerai de Fe des tourbières (« bog ore ») montre que la géochimie en roche totale est utilisable pour discriminer les ferricrètes de KOB des gossans au premier ordre, mais qu'il convient d'implémenter les bases de données avec des analyses de gossans se développant au-dessus de gisements de type iron-oxides-copper-gold deposits comme ceux exploités en Inchiri (e.g. gisement de Guelb-Moghrein, près d'Akjoujt).

International audience

International audience; Iron oxide nanoparticles (IONPs) are a promising material for the remediation of trace elements which are a significant source of soil pollution. Thus, as part of improving phytoremediation processes, the addition of IONPs to soil was tested in this study. A long-term experiment was performed in pot to assess the potential of magnetite (Fe3O4) nanoparticles (NPsMagn) to modify lead (Pb) availability to sunflower (Helianthus annuus) and its behavior in a water-soil-plant system under repeated water-deficiency stress. Plants were grown either in control soil, Pb polluted soil (final added lead 375 mg kg-1), Pb polluted soil containing 1 % dry weight NPsMagn or Pb polluted soil containing 1 % dry weight micro-sized magnetite for 90 days. Pb polluted soil and Pb treated soil containing NPsMagn do not affect plant growth but NPsMagn allow reduced oxidative impact as a decrease in lipid peroxidation was observed in their presence. Magnetic susceptibility measurements and Fe content in sunflower plants and leachates suggest that NPsMagn penetrate the roots but are not dispersed in soil solution. In addition, Pb content increased by 102 % and 22 % respectively in leaves and stems of plants treated with NPsMagn. Based on Pb content in soil solutions, NPsMagn decrease Pb in leachate by 50 %. During water stress periods, NPsMagn significantly improve water retention in soil and relative water content in plants. As a result of this, NPsMagn improve Pb availability and accumulation in sunflower plants in TEs contaminated soils unfavorable to plant growth. This study also highlights favorable effects of NPsMagn on Pb stabilization into soil, reducing their loss in leachates and on plant tolerance during water stress periods.

International audience; Eclogitization reactions of plagioclase-bearing rocks in water-limited environments are often incomplete. In such domains, metamorphism and strain localization interact, yielding complex strain-transformation patterns in the field. This is the case in the granulite facies anorthosites of Holsnøy, where partial eclogitization proceeds along digitations in the least strained domains. These areas are among the rare examples of preserved early eclogitization textures. The aim of this study is to assess the mechanical alteration induced by plagioclase breakdown reactions, through a detailed petrological study of the very first increments of the eclogitization process, expected to be preserved at the tip of a digitation in an apparently undeformed granulite block. We show that (i) the zoisite-forming reaction within plagioclase grains occurs unbalanced and initiates mechanical twinning, and subgrains individualization, and (ii) kyanite-analcime association at plagioclase grain boundaries gives evidence of partial melting, which might have affected the rock near the peak P–T conditions in response to early water infiltration. This transient partial melting stage results in the re-crystallization of μm-scale plagioclase grains. Intra-grain and grain boundary transformations therefore induce an effective grain size reduction. It constitutes an alteration of the overall aggregate properties of the burying continental rocks, prior to any significant deformation, at potentially low differential stress. Partially transformed granulites are eventually weaker than initial granulites and are prone to later strain localization.

The Palaeocene–Eocene Thermal Maximum (PETM) is one of the most important Cenozoic climatic events shaping modern biodiversity, yet reconstructions of its palaeobiomes remain controversial. Here we describe Gesomyrmex gallicus sp. nov., a new, extinct species of the ant genus Gesomyrmex Mayr, 1868, based on minor and major workers preserved in the early Eocene amber of Oise, France. Although there are only seven known extant species in the genus, all confined to warm and humid forests of SE Asia, the fossil record of Gesomyrmex indicates that the genus once radiated across Eurasia. The new species therefore provides direct evidence that this radiation likely co-occurred with the PETM. This observation constrains palaeoclimatic reconstructions of the Early Eocene by requiring the presence of an extensive, homogeneous and interconnected rainforest-like biome across palaeo-Eurasia, a scenario otherwise corroborated by pollen assemblages. The phases of regression of warm and humid forests and the widening of dry biomes probably occurred later during the Eocene, in between hyperthermals, and were probably less extensive than some computer models predicted.

Editorial on the Research Topic Further rare earth elements environmental dissemination: Observation, analysis, and impacts Thanks to their unique properties, the so-called "rare Earth elements" (REEs) are present in daily life technological devices in all sectors, including the high-tech, automotive, energy storage, and agricultural sectors. Many new technologies have been developed to limit greenhouse gases (wind turbines and hybrid cars, etc.); these are known as greentech products, which are based on the use of these strategic elements, hitherto in negligible quantities in the environment (e.g., REE). As a result, their dissemination pathways and threats to the population are poorly understood. Therefore, the corresponding exposomes are particularly poorly characterized. REE are thus qualified as emerging pollutants, and disruptions in their (bio) geochemical cycles have already been highlighted (e.g., Kulaksız, and Bau, 2007). The disturbances are expected to increase, since the growing development of green technologies will be accompanied by an increase in their extraction (i.e., their recycling is non-existent at present, since it is less profitable than their extraction). In the European Union (EU), they are currently not extracted, even if some deposits have been identified in Denmark, Finland, Greece, Norway, and Sweden, and some are even being developed by mining companies (EURARE, 2017). The EU is reliant on REEs imports from overseas, mainly from China (McLead, 2019), which comes with related potential socioeconomic implications due to the external dependence on such strategic raw materials. Currently, the One Health effects of REEs mining (i.e., those caused by ore mine tailings and active/abandoned mines), their use, and the end-of-life of products containing REEs, such as the alteration of their biogeochemical cycles, are still unknown. This special issue aims to showcase a variety of perspectives in how REEs can be present into the environment and how REE can potentially interact with living organisms including human beings (Brouziotis et al., 2022a). It introduces a comprehensive, even if not exhaustive, collection of original research articles in topics including cerium (Ce) anomaly as a potential tracer for paleo-oceanic redox conditions (Cao et al., 2022), the

International audience; During the MIS 4 in Southwestern France, Quina Neanderthal from the north of the Aquitaine was characterized by a hunting specialization on the reindeer and the lack of diversity in their diet. They developed task-specific locations dedicated to the capture, the butchery, and the consumption of reindeer, and the whole society seems, in this region, to be dependent on this food resource. In this context, the site of Chez-Pinaud at Jonzac (France) occupies a specific place. First, interpreted as a reindeer kill and butchery site, the recent recovery of the site underlines the importance of the large ungulate (horse and bison) to the faunal spectrum (30% of the NISP). Considering the quantity of meat and grease that these species can provide to hunters, the new zooarchaeological analyses suggest that at least the horse may have played a major role in the diet of the Neanderthal population. Since Jonzac is one of the largest sites for this period, these results relativize the importance of reindeer specialization of the Quina population and the lack of diversityl in their diet.

The Himalayan mountain range produces one of the steepest and largest rainfall gradients on Earth, with >3 m/yr rainfall difference over a ∼100 km distance. The Indian Summer Monsoon (ISM) contributes more than 80% to the annual precipitation budget of the central Himalayas. The remaining 20% falls mainly during pre-ISM season. Understanding the seasonal cycle and the transfer pathways of moisture from precipitation to the rivers is crucial for constraining water availability in a warming climate. However, the partitioning of moisture into the different storage systems such as snow, glacier, and groundwater and their relative contribution to river discharge throughout the year remains under-constrained. Here, we present novel field data from the Kali Gandaki, a trans-Himalayan river, and use 4-year time series of river and rain water stable isotope composition (δ18O and δ2H values) as well as river discharge, satellite Global Precipitation Measurement amounts, and moisture source trajectories to constrain hydrological variability. We find that rainfall before the onset of the ISM is isotopically distinct and that ISM rain and groundwater have similar isotopic values. Our study lays the groundwork for using isotopic measurements to track changes in precipitation sources during the pre-ISM to ISM transition in this key region of orographic precipitation. Specifically, we highlight the role of pre-ISM precipitation, derived from the Gangetic plain, to define the seasonal river isotopic variability across the central Himalayas. Lastly, isotopic values across the catchment document the importance of a large well-mixed groundwater reservoir supplying river discharge, especially during the non-ISM season.

Body fossils have been discovered in the Fortunian deposits of the Rozel Cape, in Normandy (NW France). The material consists of about 80 specimens preserved on a shale surface, recently observed at the base of a cliff at the Cap Rozel, in the Cotentin region. The fossils, centimetric in size, have an elliptical outline, with a peripheral bulge, generally without other conspicuous ornamentation, but showing sometimes concentric or radial lines possibly of taphonomic origins. In addition, these body fossils are preserved parallel to the bedding plane, locally rich in horizontal trace fossils (e.g. Archaeonassa Fenton & Fenton, 1937, Helminthoidichnites Fitch, 1850, Helminthopsis Heer, 1877) and also complex treptichinids burrows (e.g. Treptichnus pedum (Seilacher, 1955)) sometimes associated with microbial mats. The sedimentological characteristics of these deposits (ripple marks, syneresis cracks) correspond to a shallow marine shelf environment, with a variable hydrodynamism in the intertidal zone, low for surfaces showing elliptic fossils and syneresis cracks, higher for surfaces with ripple marks. These new discoveries unravel the potential of the Fortunian strata from Normandy and provide new information about the early Cambrian biocenoses.; Des organismes fossiles ont été découverts dans les dépôts d’âge Fortunien, en Normandie (NO France). Le matériel comporte environ 80 spécimens préservés sur une même surface, dans des siltites récemment observées à la base des falaises du Cap Rozel, dans le Cotentin. Les fossiles, de taille centimétrique, ont un contour elliptique, avec un bourrelet périphérique, généralement sans autre ornementation nette, mais comportant exceptionnellement des structures radiales ou concentriques pouvant être d’origine taphonomique. Ces fossiles sont associés à diverses traces fossiles horizontales (e.g. Archaeonassa Fenton & Fenton, 1937, Helminthoidichnites Fitch, 1850, Helminthopsis Heer, 1877), et des terriers complexes de type treptichinides (e.g. Treptichnus pedum (Seilacher, 1955)). Les organismes et traces fossiles sont recouverts de mattes algaires. Les caractéristiques sédimentologiques de ces dépôts (rides oscillatoires et unidirectionnelles, fentes de synérèse) correspondent à un environnement de plateforme marine peu profonde, avec un hydrodynamisme variable en zone intertidale, faible pour les surfaces à organismes elliptiques ou fentes de synérèse, plus forte pour les faciès à rides de vagues. Ces découvertes révèlent le potentiel des couches fortuniennes de Normandie et apportent de nouvelles informations fondamentales pour la connaissance des biocénoses du Cambrien basal.

International audience; Emission of colloids from treatment wetlands solid deposit (SD) may affect the speciation, toxicity and transfer of organic and inorganic pollutants, thereby controlling the associated environmental risks. This study investigated the nature of the colloids and their influence on the leaching of major and trace elements over a wide range of pH between 2 and 12. Results evidenced the mobilization of high quantity of organic carbon leached from the SD and Al-Fe colloidal minerals embedded by large organic molecules. Based on their varying affinity for the different colloidal phases, three groups of chemical species were established: (i) elements with low affinity for colloidal phases, mainly released in truly dissolved fraction (30 kDa), preferentially associated to organic colloids (Li, Ca, Mg, Sr, Ba, Mn, Zn) or to mineral colloids (Pb, Cr, Sc, Y); and (iii) element with high affinity for large and truly dissolved organic molecules (Cu, Co, Cd, Ni). Differences observed in the partitioning of elements can be attributed to variations in the pH/Eh of the solutions, the nature of the colloidal phases, and the ionic properties of the considered elements. Small pH variations were found to modify drastically the speciation of the elements solubilized with potential effect on their (bio)availability. Results obtained on this study can be used to enhance wastewater treatment through constructed wetland process and improve recovery technics applied on solid deposits (agriculture, compounds extraction…).

Miocene Dryinidae are relatively well-known compared to other Chrysidoidea families. But most taxa (16 out of 17 described species) derive from the amber mines of the Dominican Republic. Here, a new fossil species of Dryinidae, Thaumatodryinus cotyi sp. nov., is described and figured from the early to middle Miocene of Totolapa (Mexico), and compared to more or less contemporaneous Dominican species. Thaumatodryinus cotyi sp. nov is noteworthy characterized by the testaceous body, the tridentate mandibles, the clypeal anterior margin outcurved, the pronotum striate rugose, the mesopleuron and propodeum areolate rugose, and the propodeum shorter than high. We also propose an up-to-date key to the subfamilies of Dryinidae and summarize the fossil fauna from Totolapa, a deposit hitherto less studied than the coeval amber from Simojovel.

The capillary bundle model, wherein the flow dynamics of a porous medium is predicted from that of a bundle of independent cylindrical tubes/capillaries whose radii are distributed according to the medium's pore size distribution, has been used extensively. However, as it lacks an interaction between the flow channels, this model fails at predicting a complex flow configuration, including those involving a two-phase flow. We propose here to predict spontaneous imbibition in quasi-two-dimensional porous media from a model based on a planar bundle of interacting capillaries. The imbibition flow dynamics, and in particular, the breakthrough time, the global wetting fluid saturation at breakthrough, and which capillary carries the leading meniscus are governed by the distribution of the capillaries' radii and their spatial arrangement. For an interacting capillary system consisting of 20 capillaries, the breakthrough time can be 39% smaller than that predicted by the classic, non-interacting, capillary bundle model of identical capillary radii distribution, depending on the spatial arrangement of the capillaries. We propose a stochastic approach to use this model of interacting capillaries for quantitative predictions. Comparing bundles of interacting capillaries with the same capillary diameter distribution as that of the pore sizes in the target porous medium, and computing the average behavior of a randomly chosen samples of such interacting capillary bundles with different spatial arrangements, we obtain predictions of the position in time of the bulk saturating front and of that of the leading visible leading front, which agree well with measurements taken from the literature. This semi-analytical model is very quick to run and could be useful to provide fast predictions on one-dimensional spontaneous imbibition in porous media whose porosity structure can reasonably be considered two-dimensional, e.g., paper, thin porous media in general, or layered aquifers.

International audience; The Palaeolithic site of La Ferrassie (SW France) has been extensively studied since its discovery during the 19th century. In addition to a large sequence including Middle and Upper Paleolithic layers, the site has yielded two very complete adult Neanderthal skeletons, five partial immature Neanderthal skeletons as well as a few isolated human remains. Currently, much of the site sequence has been dated by radiocarbon and OSL but the dating of the human skeletal remains is still a matter of debate. Here, we present the OSL dating of a still consolidated sediment sample associated with the Neanderthal skeleton La Ferrassie 1 (LF1), unearthed by Peyrony and Capitan in 1909 and preserved at the Musée de l’Homme (Paris, France). This block of sediment is crucial as it constitutes the first possibility to date a sample in close association with the specimen. This sample is included in a chronological model at the scale of the site, with the aim to estimate the ages of three Neanderthal individuals: La Ferrassie 1, 2 and 8 (LF1, LF2 and LF8). Two chronological modelling tools (OxCal and BayLum/ArchaeoPhases) are first applied to previously published radiocarbon ages and compared. Chronological inferences show that the BayLum/ArchaeoPhases model provides posterior probability densities, or statistical inferences, that are more consistent with the measured data. When including OSL ages in the BayLum model, we can conclude that all three studied individuals date from the late Middle Palaeolithic (

International audience; The Cenozoic Avaj volcano-plutonic rocks in central Urumieh-Dokhtar magmatic arc (UDMA) encompass gabbro, and basalt to rhyolite, chemically akin to those from continental arcs. U–Pb geochronology on zircon yielded ages of 23.69 ± 0.48 Ma, 24.71 ± 0.38 Ma, 20.92 ± 0.14 Ma, and 19.25 ± 0.13 Ma for gabbro, basalt, trachyandesite, and rhyolite, respectively. εHf(t) values for zircon grains are ranging from − 1.4 to + 6.2. The data display narrow ranges of initial Pb isotopic ratios and εNd(t) values, implying a fairly homogeneous source. Moderate 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb, high 143Nd/144Nd ratios of the mafic samples highlight the role of mantle components. The isotopic ratios–incompatible trace elements modelings reveal ~ 2% of the melt come from the melting sediments in the petrogenesis of Avaj igneous rocks. The central UDMA with ages ranging from 42–38 Ma and 25–18 Ma, respectively, must have experienced two relatively brief periods of important magma production separated by ~ 14–15 M.y. The early period of magma production correlates with the Middle Eocene Climatic Optimum (MECO), while the second magmatic period of the central UDMA is not associated with increasing CO2 contents in the atmosphere. The plutons of the older group are generally located to the east of those from the younger group suggesting a SW-directed migration of the arc following slab rollback. No systematic change of source compositions and magma formation is observed between the older and younger rocks implying similar magma sources and subduction input from the Eocene to Miocene. The potential effect of the UDMA magmatic activity on the global climate apparently does not reflect decreasing subduction of carbonate.

International audience; Sediments from the 2.1- to 1.9-billion-year-old Francevillian Group in southeastern Gabon include centimeter-sized pyritized structures suggestive of colonial organisms (El Albani et al., 2010), some of which may have been motile (El Albani et al., 2019). However, these interpretations were largely based on morphological and geochemical characteristics that lack metabolic clues and/or can be explained by abiotic processes. To move this work forward, we describe other centimeter-sized specimens, loosely referred to as lenticular forms (LF), from the same area and apply a more holistic approach including morphology, mineralogy, and geochemistry. The objects are 0.2–4 cm in diameter, and most of them are endowed with a regular brim that scales proportionally to external diameter reminiscent of biological order, hence rendering the LF putative biogenic traces. The LF are perfectly delineated in every direction and deflect the sedimentary layers on which they rest. X-ray microtomography further demonstrates that the LF are syn-depositional features and not concretions, while lead isotope systematics indicate that the geochemical imprint of diagenesis is inconsequential. Low sulfur content is largely concentrated in the organic matrix, and scarcity of pyrite and its persistence as micron-sized crystals show that the role of sulfate reduction is minor. Most interestingly, the fillings of the LF cavities show large and correlated excesses of organic carbon and zinc, with the latter being distinctly enriched in its light isotopes. The geochemical anomalies of the fillings relative to the host rock, notably those associated with Zn, clearly were buried with the LF, and further imply biogenicity. In this regard, a ten-fold increase in LF size towards the top of the black shale series hosting the LF might be related to increasing Zn (nutrient) availability. Although we cannot conclude with any certainty what these remnant organisms were, their features all taken together are evocative of very large agglutinate protists that grazed on bacterial biomass either in the water column or as benthic mats.

International audience; The past diversity of vespid wasps is relatively poorly documented. Many early-diverging fossil subfamilies are only represented today by a single or a few species. Therefore, the delineations of these clades and the early evolutionary history of the family remain difficult to decipher and require additional fossil occurrences. Here, a new genus and a new species of vespid are described and illustrated from Burmese amber as Vespatula condaminei n. gen., n. sp., and placed in a new subfamily Vespatulinae n. subfam. This description provides significant morphological evidence to discuss the limits of the Priorvespinae and of the genus Alivespa, leading to its transfer into the Vespatulinae n. subfam. The placement of the recently described genus Archaeovespa is briefly discussed. The phylogenetic value of the clustered secondary hamuli recorded in the new genus is put into perspective with respect to the rest of the Vespoidea and discussed in light of recent phylogenomic analyses.

International audience; This study discusses the hydrothermal formation of romanechite (Ba0.7Mn4.5O10.1.1H2O) in the Romanèche Mn deposit and the significance of its age by combining ore petrogenesis and 40Ar/39Ar ages. Romanechite occurs as a minor phase in various manganese deposit types and remains poorly studied in comparison with other K-bearing Mn oxides (i.e., coronadite group) because of its scarcity, small grain size, intermixing and poor crystallinity. The fault-controlled Romanèche Mn deposit (Massif Central, Eastern France) investigated herein exhibits a well-crystallized and late stage massive romanechite ore occurring in a quartz-barite-fluorite gangue. Petrographical and geochemical data support manganese ore formation under sub-aerial conditions with temperatures close to fluorite precipitation (100–200 °C) and characterized by a Mn-Ba-W-As association. Five out of the eight studied samples have produced 40Ar/39Ar plateau ages ranging from 25.2 ± 0.3 to 18.2 ± 0.5 Ma. Despite a low K content (0.1–0.6 wt% K), the good crystallinity of romanechite due to its epithermal formation likely favours a better production and/or retention of the radiogenic argon than poorly crystallized phases of supergene origin. Therefore, the dataset identifies a period of at least c. 7.6 My of discontinuous hydrothermal activity, which is consistent with graben-related fault reactivation and likely volcanic activity in the Massif Central. Ultimately, this study confirms the feasibility of romanechite 40Ar/39Ar dating.

The generalized ‘laws’ of intraspecific variability in ammonites are used as a predictive tool to define the limits of poorly known species of the early Heteroceratidae (Lazariniceras, heteromorph ammonites), based on the construction of the Heteroceras theoretical model of variation. The methodology is described and the model is confronted with the palaeontological data. The discussion of the results shows that the variability observed for Lazariniceras takes up most of the continuous variation of the theoretical model. To minimize bias, particular attention was paid to the strict stratigraphic control of the raw data (8 sections studied). Thus, and for the good application of the theoretical model, the stratigraphic canvas and the systematics of the groups studied were refined and discussed: (1) the abandonment of the Gerhardtia sartousiana Zone is proposed in favor of the new Camereiceras limentinum Zone; (2) Heteroceras astierianum, Heteroceras tardieui and Martelites bifurcatus are rehabilitated; and (3) Lazariniceras heterostylia sp. nov. and Lazariniceras lhaumeti sp. nov. are introduced while Lazariniceras astierianum is redefined. Once the theoretical model of the variation has been obtained, it was then possible to propose phylogenetic reconstruction hypotheses using the cladistic tool crossed with the stratigraphic data, used to study the evolutionary patterns and processes of the group. The results show that: (1) Lazariniceras is unambiguously a Heteroceratidae despite the absence of the early helical coiling; (2) Lazariniceras originates within the Toxancyloceras; (3) Ancyloceratidae is a paraphyletic taxon; (4) evolution of the studied group is expressed by changes in adult size, heterochronies and innovations.

International audience; Thermal methods, particularly the in situ steam-based practices, used for oil production from oil sands and heavy oil reservoirs are the leading technology for enhanced oil recovery (EOR) in such reservoirs. However, a majority of these techniques, such as steam-assisted gravity drainage, cyclic steam stimulation, and steam flooding, are on the verge of exhaustion. Yet, the enduring interactions between rock and steam, bitumen recovery, and improving heavy oil recovery are the main challenges in the poststeam injection era. Here, we reviewed the experimental and field applications of the EOR methods and the recovery mechanisms behind each method in the poststeam injection era, in heavy oil reservoirs with different lithologies. Furthermore, several other thermal techniques, their applications, and their attributed pros and cons are discussed in this chapter.

Essentially all hydrogeological processes are strongly influenced by the subsurface spatial heterogeneity and the temporal variation of environmental conditions, hydraulic properties, and solute concentrations. This spatial and temporal variability needs to be considered when studying hydrogeological processes in order to employ adequate mechanistic models or perform upscaling. The scale at which a hydrogeological system should be characterized in terms of its spatial heterogeneity and temporal dynamics depends on the studied process and it is not always necessary to consider the full complexity. In this paper, we identify a series of hydrogeological processes for which an approach coupling the monitoring of spatial and temporal variability, including 4D imaging, is often necessary: (1) groundwater fluxes that control (2) solute transport, mixing and reaction processes, (3) vadose zone dynamics, and (4) surface-subsurface water interaction occurring at the interface between different subsurface compartments. We first identify the main challenges related to the coupling of spatial and temporal fluctuations for these processes. Then, we highlight some recent innovations that have led to significant breakthroughs in this domain. We finally discuss how spatial and temporal fluctuations affect our ability to accurately model them and predict their behavior. We thus advocate a more systematic characterization of the dynamic nature of subsurface processes, and the harmonization of open databases to store hydrogeological data sets in their four-dimensional components, for answering emerging scientific question and addressing key societal issues.

International audience; Transport in subsurface fractured rocks is strongly affected by the variability of the velocity field, which in complex fracture networks may vary broadly. Because the rock matrix is almost impervious, the flow occurs in the network of connected fractures, which exhibits multiscale features spanning several orders of magnitude, that is, fracture size ranging from millimeters to hundreds of meters, with a small number of fractures acting as preferential flow paths where most of the fluid flow channelizes (Bonnet et al., 2001; Goc et al., 2010; C. F. Tsang & Neretnieks, 1998). Heterogeneity at different scales in fracture aperture and hydraulic conductivity implies strong heterogeneity in flow rates and diffusive processes, leading to behaviors that cannot be captured by traditional theories, and field-scale observations that are difficult to predict (Becker & Shapiro, 2003). Understanding the impact of multiscale heterogeneity and network connectivity on advective and advective-diffusive transport is critical for many scientific and engineering applications including geothermal energy, nuclear waste disposal, waste-water injection, and water resource protection. It is key to improve our capacity of characterizing the geometry of the fracture network and identifying connected structures by means of field tests, such as conservative solute or heat tracer experiments. They typically comprise the interpretation of breakthrough curves (BTCs) to yield information on the structure of the fractured systems which drive flow and transport processes. In natural fractured media, transport of both solutes and heat behaves different from traditional Fickian models, where a constant dispersion coefficient can describe the impact of flow fluctuations occurring at the small scales on solute and thermal spreading. Solute transport through fractured media often exhibits anomalous (non-Fickian) behavior, with non-symmetrical BTCs characterized by power-law post-peak tails (Berkowitz & Scher, 1995). This behavior is mostly controlled by the structure of the interconnected network rather than by the variability in fracture aperture, the latter leading to local flow fluctuations within an individual fracture, but not significantly influencing flow, and thus advective transport, at the network scale (Frampton et al., 2019; Makedonska et al., 2016). Yet, linking structural and hydrodynamic properties to large-scale transport behavior is challenging because of the complexity of the fracture network (Hyman, Dentz et al., 2019a, 2019b; Kang et al., 2020). Besides the heterogeneity of advective displacement, transport is also affected by diffusive exchange between the fluid circulating in the fractures and the rock matrix, which can be assumed as a non-flowing (or immobile) region. While molecular diffusion of solutes has negligible effects on the observed response (Becker & Shapiro, 2000), in the case of heat transport the fluid-rock diffusive exchange strongly modifies the BTC (Carrera et al., 1998)

International audience; Belemnites were a group of Mesozoic coleoids with a global distribution from the Early Jurassic to the Late Cretaceous. During the Late Jurassic–Early Cretaceous, Gondwana's marine shelves were dominated by Belemnopsis and Hibolithes populations. In contrast to the Austral Basin, where both genera are quite common, their record in the Neuquén Basin (Argentina) is rather scarce and poor, probably due to a combination of locally unfavorable environmental conditions and predation pressure. Here we describe a new belemnite association from the Tithonian of the Vaca Muerta Formation from southern Mendoza and northern Neuquén provinces. Belemnite's findings are assignable to the Tithonian Windhauseniceras internispinosum and Corongoceras alternans Andean ammonoid Biozones. The studied rostra are identified as Belemnopsis cf. B. patagoniensis, Belemnopsis cf. B. launceloti, and Hibolithes argentinus? Affinities of the Neuquén Basin belemnite fauna are referred to the Madagascan-Eastern Africa associations (Ethiopian Subprovince, Tethyan Province), adding evidence to an established Trans-Gondwana seaway enabling the connection between those areas from the Tithonian onwards.

Paleoxyela nearctica gen. et sp. nov., is described from the upper Eocene of Florissant Formation in Colorado. We placed Paleoxyela gen. nov. in the subfamily Macroxyelinae and the tribe Macroxyelini based on the numerous wing venation characters visible on the specimen. Proxyelia pankowskii gen. et sp. nov. is described from the lower Eocene Fossil Lake deposits of the Green River Formation in Wyoming. We placed Proxyelia gen. nov. in the subfamily Macroxyelinae and the tribe Xyeleciini based on the numerous wing venation characters visible on the specimen. These new records of the family Xyelidae are of particular importance to better understand the past diversity of the clade and propose hypotheses about their diversification. Extant Xyelidae inhabit temperate Northern Hemisphere forests, and most of their larvae feed on conifers, which may explain why they are relatively poorly diversified compared to the other symphytan families. We suggest that the global decline in conifers and the reduced diversity of extant host trees partly explain the diversity of extant Xyelidae. We correlate the biome repartition during the Eocene to that of the extant xyelid.

In crystalline basement aquifers, groundwater resources are mainly near subsurface, marked by wide horizontal and vertical variations in hydrodynamic properties. Streamflow timeseries contain information about hydrodynamic properties during baseflow period of the discharge data. This work aims to extract from the hydrological chronicles the vulnerability factors of the watersheds to low flows (hydrodynamic properties and their heterogeneity), to correlate the properties with the lithology and to evaluate the response of the aquifers to climate change. The hs1D model describes the fluxes at the hillslope scale and has been used to estimate the hydrodynamic properties of 79 watersheds in Brittany. Here, we propose a novel modeling approach based on two equivalent hillslopes to capture spatial and temporal variabilities of the main processes. The calibrated properties are then related to the lithology of the watersheds in a regionalization perspective. This approach highlights the presence of both slow and fast flows throughout the watersheds, constrained by the permeability and diffusivity of the two hillslopes. Exploration maps provide information on watershed storage capacities. The correlation of hydrodynamic properties with lithology suggests that regional models can be constrained by a limited amount of observed data despite the complexity of crystalline basement aquifer flows.; Dans les aquifères de socle cristallin, les ressources en eau souterraines sont principalement de proche subsurface, marquées par de larges variations horizontales et verticales des propriétés hydrodynamiques. Les chroniques hydrologiques contiennent de l’information sur les propriétés des milieux souterrains dans la partie récession de la série temporelle des débits. Les objectifs de la thèse étaient d’extraire des chroniques hydrologiques les facteurs de vulnérabilité des bassins versants aux étiages (les propriétés hydrodynamiques et leur hétérogénéité), de corréler les propriétés et la lithologie et d’évaluer la réponse des aquifères face aux changements climatiques. Le modèle hs1D décrit les écoulements à l’échelle du versant et a été utilisé pour estimer les propriétés hydrodynamiques de 79 bassins versants en Bretagne. Ce modèle a été adapté pour tenir compte de l’hétérogénéité des processus à partir d’une approche à deux versants. Les propriétés calibrées sont alors mises en relation avec la lithologie des bassins versants dans une optique de régionalisation. Cette approche met en avant la présence à la fois d’écoulements lents et rapides sur l’ensemble des bassins versants, contraints par la perméabilité et la diffusivité des versants. Les cartes d’exploration fournissent des informations sur les capacités de stockage des bassins versants. La corrélation des propriétés hydrodynamiques avec la lithologie suggère que les modèles régionaux peuvent être contraints par une quantité de données restreinte malgré la complexité des écoulements des aquifères de socle.

The Rennes area is not spared by climate change. Abnormal conditions are alreadyweakening the basin's drinking water supply system. But what will happen in the future? The managers of Eau du Bassin Rennais need tools to predict the evolution of water resources upstream of the interest catchments. To meet this demand, a hydro(geo)logical modeling approach has been developed, adapted to the Brittany region with shallow basement aquifers, focusing on subsurface-surface relationships. Based on the hydrographic network, a model calibration method was innovated to estimate subsurface properties. The process-based modeling developed is able to simulate the stream intermittency, an indicator of watershed resilience. Once the calibration is validated, the hydrogeological models are forced by multiple climate projections, ranging from 1980 to 2100, and for different greenhouse gas emission scenarios (RCP). The hydrological simulation results provide an envelope of likely future trajectories of groundwater storage, streamflow, and stream intermittency. In general, the projections anticipate an extension of water deficit periods, with an increased occurrence of consecutive drought years. The knowledge provided and the operational tools developed in the framework of this thesis allow, on the one hand, to progress on burgeoning research questions, and on the other hand, to offer new perspectives for anticipating and optimizing water management strategies, at the territory scale.; Le bassin rennais n’est pas épargné par le changement climatique. Les conditionsinhabituelles fragilisent déjà le système d’alimentation en eau potable du territoire. Mais qu’en sera-t-il dans le futur ? Les gestionnaires d’Eau du Bassin Rennais ont besoin d’outils pour prédire l’évolution des ressources en eau en amont des ouvrages de captages. Pour y répondre, la démarche de modélisation hydro(géo)logique développée, adaptée au contexte géologique de socle en Bretagne, s’est concentrée sur les relations entre la nappe d’eau souterraine et les cours d’eau. En se basant sur le réseau hydrographique de surface, une méthode de calibration des modèles a été innovée pour estimer les propriétés de la subsurface. L’approche de modélisation basée sur les processus hydrogéologiques reproduit l’intermittence des cours d’eau, indicateur de la résilience des bassins versants. Une fois la calibration validée, les modèles hydrogéologiques sont forcés par de multiples projections climatiques, allant de 1980 à 2100, et selon différents scénarios d’émission de gaz à effet de serre (RCP). Ces simulations hydrologiques fournissent une enveloppe de trajectoires probables d’évolution future du stock d’eau souterraine, du débit des cours d’eau, et de l’intermittence du réseau hydrographique. De manière générale, les projections prévoient une extension des périodes de déficit en eau, avec une occurrence accrue d’années de sécheresses consécutives. Les connaissances apportées et les outils opérationnels développés dans le cadre de cette thèse permettent, d’une part, de progresser sur des questions de recherches en plein essor, et d’autre part, d’offrir de nouvelles perspectives d’anticipation et d’optimisation des stratégies de gestion de l’eau, à l’échelle du territoire.

International audience; Ancient fluvial deposits typically display repetitive patterns in their depositional architecture such as alternating intervals of laterally-stacked, high-amalgamation (HA) channels, and floodplain-dominated intervals with vertically-stacked, low-amalgamation (LA) channels. Such patterns are usually ascribed to base-level driven changes in accommodation space. However, “upstream” factors such as water discharge and sediment flux have also been recognized for their potential role in controlling stratigraphic architecture but have not been tested in ancient fluvial systems. Here, we use paleohydraulic reconstructions to document riverbed gradient evolution within three middle Eocene (~40 Ma) fluvial HA-LA sequences in the Escanilla formation in the south-Pyrenean foreland basin. We show, in an ancient fluvial system, that river slope was primarily driven by climate-controlled water discharge variations rather than base-level changes as commonly assumed. These results have fundamental implications for the interpretation of the fluvial stratigraphic record and for our ability to reconstruct ancient hydroclimates.

International audience; Identifying the circulation of fluids in subduction zone system and understanding their role on the megathrust fault slip modes remains one of the outstanding challenges in Earth Sciences. As these faults have the capacity to generate mega-earthquakes, the associated hazard to the society is significant.In recent years, studies in Japan, Costa Rica and New Zealand try to find the processes that control slip behaviours through marine campaigns and IODP drillings. The Ecuadorian margin is an exceptional laboratory to continue this international effort by adding a subduction zone to the list of those with contrasted slips at shallow depth. In April 2016, a Mw 7.8 earthquake broke the southern part of the 1906 earthquake rupture zone, causing hundreds of deaths and millions of dollars in damages along an increasingly populated coastline. The seismological and geodetic network in place since several years and a dense post-seismic deployment, contributed to observe and define the rupture zone and areas affected by aseismic slip on the shallowest portion of the megathrust fault.Thanks to two marine campaigns (HIPER and SUPER) and other existing onshore/offshore data acquisition, our project Fluid2Slip will participate to determine the exact role of fluids on slip behaviour around the updip part of the seismogenic megathrust fault by localizing fluids and seismicity, imaging fault properties and deformation. Our large experiment allowed a high density onshore/offshore deployment to perform shots and earthquakes FWI (Full Waveform Inversion) and obtain sufficient resolution to tackle the role of fluids with respect to interplate roughness, the nature of sediments, upper plate and lower plate’s structural heterogeneity in seismic/aseismic slip behavior. In addition, subsurface observation and fluid geochemistry will help detect fluid flow and discuss the path they take through the upper plate.

International audience; The Cenozoic history of the Tibetan Plateau topography is critical for understanding the evolution of the Indian-Eurasian collision, climate, and biodiversity. However, the long-term growth and landscape evolution of the Tibetan Plateau remains ambiguous, it remains unclear if plateau uplift occurred soon after the India-Asia collision in the Paleogene or later in the Neogene. As the landscape evolution is controlled mainly by mountain uplift and surface processes, the present-day river profiles and the drainage basin geometries preserve important information that can be extracted to infer the long-term history of mountain uplift with numerical models. Here we focus on the southeastern Tibetan Plateau where three of the world’s largest rivers draining the Tibetan Plateau (the Yangtze, Mekong, and Salween Rivers, i.e., Three Rivers) have incised deep valleys with distinctive geomorphic signatures. We reproduce the uplift history of the southeastern (SE) Tibetan Plateau using a 2D landscape evolution model, which simultaneously solves fluvial erosion and sediment transport processes in the drainage basins of the Three Rivers region. Our model was optimized through a formal inverse analysis with a large number of forward simulations, which aims to reconcile the transient states of the present-day river profiles. The modeling results were ultimately compared to existing thermochronologic and paleoelevation datasets to help decipher between competing tectonic models that predict contrasting topographic evolutions. Our results suggest initially low elevations during the Paleogene, followed by a gradual southeastward propagation of topographic uplift of the plateau margin until present day. Our modeling thus does not support Paleogene formation of the SE Tibetan Plateau with a major subsequent degradation via upstream fluvial erosion. The quantitative constraints on landscape evolution achieved based on drainage patterns in SE Tibet indicate a powerful tool potentially applicable to other regions to infer important implications for the evolution of Indian-Eurasian collision, Asian monsoons, and biodiversity, as well as the geodynamic forces involved in collisional orogens.

Changes in groundwater levels associated with hydroclimatic variations and anthropogenic water extraction can deform the solid Earth, both elastically and inelastically. Satellite-based geodetic techniques which measure the Earth’s surface displacements can thus be used to track changing conditions in aquifer systems. However, accurately extracting groundwater-induced deformation signals still poses a challenge as geodetic techniques like GNSS and InSAR also record noise, systematic errors and other sources of deformation. In this study, we take advantage of the relatively dense in situ groundwater monitoring network of the Sacramento Valley aquifer in California to constrain its deformation and hydromechanical properties. We start by characterizing the main seasonal and multiannual fluctuations in groundwater levels with an Independent Component Analysis (ICA) and exploit the resulting temporal signature to extract the associated deformation field from GNSS and InSAR time series. We then develop a poroelastic model of the aquifer to invert for its elastic storage capacity and estimate the respective contributions of elastic and inelastic processes to long-term subsidence. Our modeling also suggests that depth-dependent elastic properties are necessary to explain the spatial distribution of horizontal poroelastic displacements measured by GNSS. This work has important implications for the sustainable management of heavily-stressed Californian aquifers but also serves as a calibration between in situ and remote sensing techniques, which is essential for the successful deployment of satellite-based groundwater monitoring in areas with sparse field-based instrumentation.

International audience; During the differentiation of terrestrial planets, the metal phase from the impactor core segregates from the silicate phase of the magma ocean. This buoyant mass forms a turbulent thermal and settles toward the proto-core. During this descent, turbulent motions induce stirring of the metallic phase and entrainment of silicates. Thermal and chemical exchanges may occur at the boundary of the stirred phases. However, homogenization between the two phases only occurs when the metallic phase reaches the diffusive length scale, where mass or heat transfer became irreversible. Based on laboratory fluid dynamic experiments and on 3D direct numerical simulations mimicking the settling of the thermal turbulent, we used the “lamellar” description of the mixing by advecting a Lagrangian material line based on velocity fields. 3D simulations strengthen the results obtained from the experimental dataset, which is only 2D. We have tracked the evolution of the material elongated as lamellae by the turbulent stirring. We have characterized the elongation rate, the aggregation of lamellae, and the probability density function of the elongation and concentration, which are not accessible from direct measurements in the experiments. We have also investigated the effect of the Reynolds and Péclet number on these quantities. Based on these results, we have produced a stochastic model able to predict the temporal evolution of the concentration field, which can be used for understanding the equilibrium between metals and silicates during the accretion of terrestrial planets.

The Permo–Triassic interval encompasses three extinction events including the most dramatic biological crisis of the Phanerozoic, the latest Permian mass extinction. However, their drivers and outcomes are poorly quantified and understood for terrestrial invertebrates, which we assess here for insects. We find a pattern with three extinctions: the Roadian/Wordian (≈266.9 Ma; extinction of 64.5% insect genera), the Permian/Triassic (≈252 Ma; extinction of 82.6% insect genera), and the Ladinian/Carnian boundaries (≈237 Ma; extinction of 74.8% insect genera). We also unveil a heterogeneous effect of these extinction events across the major insect clades. Because extinction events have impacted Permo–Triassic ecosystems, we investigate the influence of abiotic and biotic factors on insect diversification dynamics and find that changes in floral assemblages are likely the strongest drivers of insects’ responses throughout the Permo–Triassic. We also assess the effect of diversity dependence between three insect guilds; an effect ubiquitously found in current ecosystems. We find that herbivores held a central position in the Permo–Triassic interaction network. Our study reveals high levels of insect extinction that profoundly shaped the evolutionary history of the most diverse non-microbial lineage.

International audience; Packings of beads confined in slowly tilted containers with a top open surface are commonly used in laboratory experiments to model natural grain avalanches and better understand and predict critical events from optical measurements of the surface activity. To that aim, after reproducible packing preparations (pouring then grid pulling out), the present work focuses on the effect of the surface fabrication, which can be scraped or soft leveled, on both the avalanche stability angle and the dynamic of precursory events (small surface reorganization) for glass beads of 2 mm diameter. A depth effect of a scraping operation is highlighted by considering different packing heights, up to 185 mm, and inclination speeds in the range 1.7-14 • /min.; Des paquets de billes confinés dans des récipients lentement inclinés avec une surface supérieure ouverte sont couramment utilisés dans des expériences de laboratoire pour modéliser des avalanches naturelles de grains et mieux comprendre et prédire les événements critiques à partir de mesures optiques de l'activité de surface. Dans ce but, après des préparations de conditionnement reproductibles (versement puis retrait de la grille), le présent travail se concentre sur l'effet de la fabrication de la surface, qui peut être grattée ou nivelée en douceur, à la fois sur l'angle de stabilité des avalanches et sur la dynamique des événements précurseurs (petite réorganisation de la surface) pour des billes de verre de 2 mm de diamètre. L'effet de profondeur d'une opération de raclage est mis en évidence en considérant différentes hauteurs d'emballage, jusqu'à 185 mm, et des vitesses d'inclinaison dans la gamme 1,7-14 - /min.

The grain-scale morphology and size distribution of sediments are important factors controlling the erosion efficiency, sediment transport and the aquatic ecosystem quality. In turn, characterizing the spatial evolution of grain size and shape can help understand the dynamics of erosion and sediment transport in coastal, hillslope and fluvial environments. However, the size distribution of sediments is generally assessed using insufficiently representative field measurements, and determining the grain-scale shape of sediments remains a real challenge in geomorphology. Here we determine the size distribution and grain-scale shape of sediments located in coastal and river environments with a new methodology based on the segmentation and geometric fitting of 3D point clouds. Point cloud segmentation of individual grains is performed using a watershed algorithm applied here to 3D point clouds. Once the grains are segmented into several sub-clouds, each grain-scale morphology is determined by fitting a 3D geometrical model applied to each sub-cloud. If different geometrical models can be tested, this study focuses mostly on ellipsoids to describe the geometry of grains. G3Point is a semi-automatic approach that requires a trial-and-error approach to determine the best combination of parameter values. Validation of the results is performed either by comparing the obtained size distribution to independent measurements (e.g., hand measurements) or by visually inspecting the quality of the segmented grains. The main benefits of this semi-automatic and non-destructive method are that it provides access to (1) an un-biased estimate of surface grain-size distribution on a large range of scales, from centimeters to meters; (2) a very large number of data, mostly limited by the number of grains in the point cloud data set; (3) the 3D morphology of grains, in turn allowing the development of new metrics that characterize the size and shape of grains; and (4) the in situ orientation and organization of grains. The main limit of this method is that it is only able to detect grains with a characteristic size significantly greater than the resolution of the point cloud.

International audience; The Juruena Terrain (Rondônia-Juruena Province) in the southeastern Amazonas State shows a NW-SE dextral shear zones system denominated Roosevelt-Guariba Transpressive Belt (RGTB). The RGTB was generated in response to intracontinental crustal reworking, juxtaposing Paleoproterozoic Juruena granitic-gneiss and coeval supracrustal associations. This granitic-gneiss basement shows high-K calcalkaline (Teodósia Suite) to transitional I-to A-type (Igarapé das Lontras Suite) signatures, produced in a continental magmatic arc setting around 1760-1740 Ma (zircon, titanite; U-Pb SHRIMP, LA-ICP-MS). New geochronological data about of the deformation and metamorphic rocks in the RGTB were obtained from migmatite paragneisses, amphibolites, S-type leucogranite (Quatro Cachoeiras Complex and Itamaraty Suite; zircon U-Pb SHRIMP) and protomylonites and mylonites (Igarapé das Lontras and Teodosia protoliths; amphibole-muscovite-sericite Ar-Ar step heating). The results suggest that Southeastern Amazonas (northern Juruena Terrain) was metamorphosed/deformed during 1530-1460 Ma under temperatures of 900 o C (zircon) to 580 o C (hornblende) and 420 o C (muscovite). The geochronological data show that the granite-gneiss basement (continental magmatic arc) and supracrustal rocks (foreland basin) were reworked by a regional event with an age interval of 1530 Ma (high grade and anatexis) to 1460 Ma (medium grade). Finally, the Juruena Terrain is affected by a younger low-T event (1300 Ma, muscovite Ar-Ar step heating) with wide NE-trending structures (e.g. Buiuçu Shear Zone). This 1.3 Ga event suggests a continental reactivation caused by the pericratonic deformation related to Candeias/ Sunsás Orogeny during the Columbia Supercontinent break-up, before the Rodinia Supercontinent assembly. In summary, the Juruena Terrain in the southeast Amazonas shows a complex metamorphic and structural intracontinental evolution, involving polycyclic events from late Orosirian to Ectasian in a convergent tectonic setting. Therefore, the Juruena Terrain shows similar accretionary histories with other orogens and has apparent long-lived connections with Laurentia (Yavapai Province) and Baltica (Transscandinavian Igneous Belt), forming the core of the Columbia Supercontinent.

International audience; The nappe stack of the Western Alps offers us a unique opportunityto discuss orogenic processes at crustal scale. Along and north of theECORS-CROP seismic line, the nappe stack consists, from top to bottom,of (i) units derived from the Sesia-Dent Blanche continental fragment,(ii) ocean-derived units (Zermatt-Grivola, Tsaté), (iii) units derivedfrom the distal part of the Briançonnais palaeomargin (Monte Rosa- Gran Paradiso), and (iv) units derived from more proximal part of thispalaeomargin, now outcropping as windows (Money Unit).We have recentlyperformed detailed mapping, structural analysis, metamorphicpetrology and geochronology in both the highest (Dent Blanche) andthe deepest (Money) units. As a synthesis, we will now discuss the metamorphicstructure of the nappe stack, which is characterized by thefollowing points :– Units involved in the subduction zone at an early stage are thrustedover units involved in the same subduction zone at a later stage, explainingwhy older eclogite-facies units (e.g. Zermatt-Grivola) arethrust on top of younger eclogite-facies (Monte Rosa- Gran Paradiso)units.– After their subduction as more or less coherent pieces, some continentalunits are sheared during their exhumation, so that higherpressuresubunits (Gran Paradiso) are thrusted over lower pressureones (Money).– The older nappe boundaries that occur at higher structural levelsare deformed (folded and sheared) when the younger nappe boundariesare formed at deeper structural levels.– Late brittle faulting (with up to 3km of vertical displacement) isa necessary requisite for understanding the present location of thenappe boundaries.Geometric and petrologic data are used to construct a consistent kinematicmodel for this transect of the Western Alps, emphasizing the roleof the inherited discontinuities from the pre-orogenic history, namelythe Variscan orogeny, the Permian extension and the Jurassic rifting.

International audience; La campagne MERCAUX 2013 d’acquisition sismique marine TrèsHaute Résolution s’est déroulée dans le cadre du projet de cartographiegéologique du plateau continental français mené par le BRGM.Elle avait pour objectif d’obtenir une imagerie sismique détaillée dusous-sol afin d’améliorer la connaissance régionale de la bordure ouestdu Bassin de Paris (Baie de Seine - Pays de Caux). Cette zone souffreen effet d’un déficit de données de subsurface à terre (sismique, puits)qui limite la connaissance de sa géologie régionale et de son évolution,notamment au cours du Méso-Cénozoïque.La campagne MERCAUX 2013 a permis l’acquisition de 1600 km desismique THR de bonne qualité dans le nord Baie de Seine et au largedu Pays de Caux, faisant suite aux 3000 km acquis en Baie de Seine en2007 et 2008 (Thèse BRGM-Université de Caen de M. Benabdellouahed,2011).Un exemple d’apport de connaissances est l’imagerie fine des géométriessédimentaires en ondulation de la craie (Coniacien-Santonien), visiblessur les falaises Etretat et Fécamp. Les données de MERCAUX2013 permettent de déterminer l’extension géographique des champs de ces géométries, de même que leurs dimensions et l’orientation des« levées » et « chenaux », ainsi que des courants impliqués dans leurformation.Les données sismiques obtenues imagent l’ensemble des séries mésocénozoïquesjusqu’au remplissage complexe au sommet des séries dubassin tertiaire nord Baie de Seine. L’imagerie sismique a égalementmontré son intérêt pour la caractérisation des déformations, et l’améliorationdu schéma structural régional.Les résultats de la campagne 2013 seront complétés par une campagnede prélèvements géologiques et d’acquisition sismique THR (MERCAUX2015) et intègreront la nouvelle carte géologiques de la zoneBaie de Seine- Pays de Caux à 1 / 250 000ème.

International audience; Dans la partie Est du bassin de l’Athabasca (BA), les minéralisationsuranifères (1.6-1.4 Ga) de type discordance sont localisées à l’aplombde la zone de transition des domaines Mudjatik et Wollaston (ZTMW).Cette zone est caractérisée par l’abondance de paragneiss migmatitiquesriches en monazites et par la présence de pegmatites minéralisées (1.85-1.7 Ga). Ces pegmatites seraient une des sources potentielles des gisementsde type ´n discordance ˙z du BA. Ces éléments suggèrent quela déformation archéenne (2.5 Ga) et/ou transhudsonienne (1.8 Ga)ainsi que la fusion partielle des métasédiments ont joué un rôle majeurdans les mécanismes de pré-concentration et de mise en solution desphases accessoires uranifères (monazite-zircon).Afin de quantifier ces phénomènes de pré-concentration métamorphiques,nous avons réalisé une étude pluridisciplinaire du socle de laZTMW. Cette approche consiste à caractériser les relations entre préconcentrationsuranifères et évolution tectono-métamorphique, ce quiimplique une étude fine du comportement des phases uranifères durantle métamorphisme et la fusion partielle. L’objectif principal de l’étudeest d’établir l’évolution P-T-t-D-M (M : Minéralisation).Le champ de déformation finie est le résultat de la superposition de deuxphases de déformation contemporaines d’une fusion partielle et de lamise en place de différentes générations de pegmatites. La phase D1correspond à une foliation peu inclinée orientée N90-N110. La phaseD2 est à l’origine de la structuration majeur N40 de la ZTMW caractérisépar le développement de zone de cisaillement D2 verticales et estcompatible avec un régime transpressif senestre régional. Les données thermobarométriques suggèrent des conditions au pic dumétamorphisme de 5-6 kbar et 800-850°C. Les données géochronologiquesobtenues sur monazite et zircon permettront de contraindre cecontexte tectono-métamorphique, les phénomènes de pré-concentrationen uranium et d’altération plus tardive.

National audience; In theWestern Alps, the Money Unit is a monocyclic unit, metamorphosedat blueschist facies during the Alpine cycle. It crops out as a tectonicwindow below the overthrusted polycyclic, eclogite-bearing unit of theGran Paradiso and its present position is the result of the Alpine tectonics.The Money Unit is considered to be Permo-Carboniferous in age,but no palaeontological or radiometric data constrain this interpretation.The Money unit exposes a sequence of clastic sediments and volcanics(Money Complex) that are intruded by a granitoid body (Erfaulet metagranite).In the Money Complex a polygenic (graphite-rich) and a monogenic(graphite-poor) meta-sedimentary formation have been recognized.The two sequences are separated by fine-grained biotite-amphibolegneisses, and by albite-bearing gneisses and amphibolites.Detrital zircon U-Pb geochronology in both meta-sedimentary formationsshows that (i) the main population is Cambrian and Ordovician inage, (ii) the youngest grains are Silurian and Early Devonian, and (iii)Carboniferous zircons are lacking. A study of the age distributions in theAlps suggests that potential source for the detrital material in the MoneyComplex is the Briançonnais basement. Late Carboniferous magmatismis widespread in the Helvetic Zone of the Alps. Permian magmatism isdominant in the Briançonnais, in the Austroalpine, and in the SouthernAlps. The lack of Carboniferous zircons in the Money Complex suggeststhat the detrital material did not derive from the erosion of theHelvetic Zone. The Helvetic Zone was separated from the Money basinby the Zone Houillère basin, where the main drainage pattern was developedfrom south to north and where the depocenters migrated northwardsfrom the Namurian to the Stephanian.We suggest that the MoneyComplex may had been located to the east of the main river drainageinside the Zone Houillère basin or alternatively may represent a smallbasin, located on the east of the Zone Houillère.

27 pages; International audience; Several diagenetic models have been proposed for Middle and Upper Jurassic carbonates of the eastern Paris Basin. The paragenetic sequences are compared in both aquifers to propose a diagenetic model for the Middle and Late Jurassic deposits as a whole. Petrographic (optical and cathodoluminescence microscopy), structural (fracture orientations) and geochemical (δ18O, δ13C, REE) studies were conducted to characterize diagenetic cements, with a focus on blocky calcite cements, and their connection with fracturation events. Four generations of blocky calcite (Cal1-Cal4) are identified. Cal1 and Cal2 are widespread in the dominantly grain-supported facies of the Middle Jurassic limestones (about 90% of the cementation), whereas they are limited in the Oxfordian because grain-supported facies are restricted to certain stratigraphic levels. Cal1 and Cal2 blocky spars precipitated during burial in a reducing environment from mixed marine-meteoric waters and/or buffered meteoric waters. The meteoric waters probably entered aquifers during the Late Cimmerian (Jurassic/Cretaceous boundary) and Late Aptian (Early Cretaceous) unconformities. The amount of Cal2 cement is thought to be linked to the intensity of burial pressure dissolution, which in turn was partly controlled by the clay content of the host rocks. Cal3 and Cal4 are associated with telogenetic fracturing phases. The succession of Cal3 and Cal4 calcite relates to the transition towards oxidizing conditions during an opening of the system to meteoric waters at higher water/rock ratios. These meteoric fluids circulated along Pyrenean, Oligocene and Alpine fractures and generated both dissolution and subsequent cementation in Oxfordian vugs in mud-supported facies and in poorly stylolitized grainstones. However, these cements filled only the residual porosity in Middle Jurassic limestones. In addition to fluorine inputs, fracturation also permitted inputs of sulphur possibly due to weathering of Triassic or Purbeckian evaporites or H2S input during Paleogene times.