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Controls on sedimentary deposits in the coastal environments of the Paris Basin at the Eocene-Oligocene transition.
No full textInternational audienceThe Eocene-Oligocene Transition (‘EOT’) marks a global deterioration in climate associated with the establishment of the Antarctic polar ice cap, but is poorly constrained in continental areas. In Europe, a marked seasonality and a major replacement of European flora and fauna by Asian species (the ‘Grande Coupure’ described by Stehlin, 1909) were recorded during this period. Deposits at the ocean-continent interface are recorded in the Paris Basin at the EOT, from the lagoon-marine to the lacustrine domains. Lithology and facies distribution are therefore controlled by mechanisms on a global and local scale (tectono and glacio-eustatism, climate, tectonic), which need to be differentiated and highlighted. We present a mineralogical, elemental and isotopic geochemistry record of three Upper Priabonian to Upper Rupelian sections located in the northern Paris basin (Cormeilles-en-Parisis, Le Pin-Villeparisis and Saint-Soupplets), near the Bray anticline. Cormeilles-en-Parisis, the westernmost, is located in the Saint-Denis synclinal and shows the most complete sedimentary sequence, more clayey and carbonaceous. It is fossiliferous but not very diverse. The Saint-Soupplets section, located on the eastern flank of the perianticlinal end of the Bray, shows the same sequence of formations as the Cormeilles-en-Parisis section, but is characterised by sandier deposits with current and erosive figures. The Le Pin-Villeparisis section, located on the western flank of the Bray anticline and between the two other sections, is truncated in its upper part and relatively condensed. It is essentially clayey and mostly barren of fossils.In the Upper Priabonian, the sedimentary record shows a tectonic pulse at the origin of terrigenous inputs and the creation of positive topography, then the Late Eocene regression and the decrease of the tectonic activity inducing the progradation of continental deposits. In the Lower Rupelian, the long-term increase in detrital terrigenous deposits and the environmental changes suggested by floral and faunal data are probably due to the combination of tectonics and eustatism. To the west (Cormeilles-en-Parisis section), a few evaporitic levels show a lagoonal environment that is almost always submerged. To the east, the sections are incomplete (erosive levels and missing formations), influenced by the structure of the anticline, which forms a topographic barrier and a positive relief. The absence of certain formations and the presence of a clearly lacustrine formation at the top of the Le Pin-Villeparisis section show the proximity of the coastline, which is more prone to emersion when subjected to tectonic uplift. Reference: Stehlin, H., 1909. Remarque sur les faunules de mammifères des couches éocènes et oligocènes du Bassin de Paris. Bull. Société Géologique Fr. 19, 488–520
CLIMAAX - Deliverable Phase 1 – Climate risk assessment
No full textRéunion Island’s Climate Risks Atlas project (RISC-RA) aims to carry out an assessment of climate risks on Réunion Island, a French overseas territory exposed to intense natural hazards. Réunion Island’s Regional council, hereafter called Region Réunion, a local public authority in charge of sustainable development and regional planning, has been managing the project since 1st October 2024 in collaboration with a scientific research group.This deliverable presents the organization, methodology and results of the RISC-RA project at the end of the first 6 months of work. The initial climate risks assessment has prioritized two main climate hazards: Droughts and Heavy Rainfall events, each already posing substantial and growing threats to socio-economic stability, infrastructure integrity, public health, and environmental sustainability. The general CLIMAAX methodology was adapted to the local context, using high-resolution climate data and local exposure and vulnerability datasets. The first phase of RISC-RA was also devoted to setting up the team's operational organization, establishing project governanceand making initial contacts with external stakeholders.Regarding the two main risks addressed during this phase, the following observations and results can be drawn:(1) Drought Risk: Droughts on Réunion Island are slow-onset hazard Island caused by prolonged periods of below-normal rainfall. The territory experienced extreme drought in December 2024 and January 2025, the driest months recorded for over 50 years. The analysis using regional climate projections indicates an increase in both intensity and spatial extent of drought risk, particularly in the northern and northwestern regions.(2) Extreme Rainfall Risk: the island holds most world records for rainfall duration over time intervals ranging from 12 hours (1144 mm) to 15 days (6083 mm). Heavy rainfall is a sudden-onset hazard expected to intensify, with projections indicating extreme rainfall events becoming more frequent, notably affecting northern, eastern, and southern coastal regions. Historical analysis identified a threshold of approximately 220 mm/day, regularly triggering catastrophic events.Phase 1 provided significant insights into regional climate vulnerabilities and risks, particularly highlighting drought and extreme rainfall as pressing concerns. This year 2025 was a perfect example of this, with a persistent heatwave during the first’s months, a severe drought in the northeastern areas, including water unavailability and water restrictions usages. This was followed by Cyclone Garance, one of the strongest cyclones experienced in La Reunion with devastating impacts.The climate risks analysis produced during phase 1 will serve as the first version of the Risk Atlas, which will be refined and discussed with local public authorities and practitioners. The findings of deliverable no. 1 will be used as the basis for the first local workshop to present the RISC-RA projectto local stakeholders, such as the Drought Committee, for example. The preliminary results for both historical data and projection will be improved in Phase 2 with case studies for the validation of vulnerability indicators and the extended analysis of heavy rainfall. At the same time, one or two new Workflow(s) will be explored
Identification of molybdenum immobilization mechanisms in naturally contaminated excavated rocks and soils stabilized with zero-valent iron
No full textInternational audienceChemical stabilization of naturally contaminated excavated materials could be used to limit environmental risks. Nevertheless, due to the low levels of contamination in such materials a more precise characterization of immobilization mechanisms is required. To overcome this lack of data, zero valent iron (Fe 0 ) was used as a stabilizing agent at rates of 1 or 3 wt% in four different sets of excavated rock and soil from the Paris basin that were contaminated with low levels of molybdenum (with a total content of from 2 to 11 mg Mo kg -1 ) but that involved leachability issues. Molybdenum (Mo) release was reduced by at least one order of magnitude after adding Fe 0 over a wide pH range (i.e. 2 < pH < 12). Geochemical modeling of pH-dependent leaching tests was done to identify potential immobilizing mechanisms. For Mo, experimental results were well represented at pH close to and below the natural pH of the samples by considering surface adsorption with iron (hydr-)oxides involving non-, mono-and bi-protonated Mo surface species. Zero valent iron stabilization remained relatively significant under alkaline conditions where complexation of anionic species was not favored. These results suggested that stronger binding mechanisms are likely to occur concomitantly with surface adsorption. Finally, thanks to their high sensitivity, μ-particle-induced X-ray emission (μ-PIXE) and μ-Rutherford backscattering spectroscopy (μ-RBS) were successfully used to directly observe Mo presence in iron (hydr-)oxides formed after addition of Fe
Geochemical footprints of IOA and IOCG deposits in Northern Norrbotten, Sweden, and Cloncurry District, Australia
No full textInternational audienceThis paper addresses the complex hydrothermal evolution of Metasomatic Iron and Alkali-Calcic (MIAC) mineral systems based on a review of the lithogeochemical footprints of IOA and IOCG deposits in the northern Norrbotten province (Sweden) and the Cloncurry district (Australia). The use of Na-Ca-Fe-K-Mg molar barcodes on a lithogeochemical diagram tailored for these mineral systems allows to depict the evolution of MIAC systems along diagnostic metasomatic paths from high (HT) to low temperature (LT) alteration facies as follows: 1) HT or LT Na alteration (300–1000 °C); 2) HT Casingle bondFe alteration (400–1000 °C); 3) HT Ksingle bondFe alteration (350–450 °C); 4) HT K and HT K-Ca-Mg alteration; 5) LT Ksingle bondFe, Na-Ca-Mg-Fe, and/or Na-Ca-Mg alteration (≤ ~350 °C); and 6) epithermal alteration (≤ 150 °C) and later stage hydrothermal veining. A distinct range of whole rock compositions and metal associations characterizes each alteration facies and can be captured by diagnostic molar barcodes and alteration indices. In northern Norrbotten, the IOA deposits are hosted in HT Casingle bondFe alteration facies but regionally intensely albitized regions are overprinted by Ksingle bondFe alteration. The IOCG deposits are hosted in MIAC systems with zones of early Na (single bondCa) alteration related to the regionally extensive albitite or scapolite alteration (Facies 1) and localized skarns. These are overprinted by HT Casingle bondFe alteration (Facies 2) and HT to LT Ksingle bondFe alteration (Facies 3 and 5). The Cusingle bondAu mineralization is not systematically associated with the iron oxide-rich breccias and the intense K-feldspar- or sericite-rich Ksingle bondFe alteration typical of many IOCG deposits worldwide. Instead, the lesser intensity of alteration and the abundance of mafic and ultramafic rocks in the environment lead to pattern enriched in Mg with relic of amphibole-rich alteration remaining in the assemblage as demonstrated for the Nautanen North IOCG deposit (Sweden). Consequently, the geochemical footprints of the Norrbotten Cusingle bondAu deposits are distinct from magnetite-group (e.g., Great Bear magmatic zone, Canada) and hematite-group (e.g., Olympic Dam, Australia) IOCG deposits even if they have all the known alteration facies of MIAC systems. Conversely, IOCG deposits in northern Norrbotten show similarities to certain deposits in the Cloncurry district of Australia. In both regions, the IOCG deposits are associated with HT Casingle bondFe and Ksingle bondFe alteration facies that commonly overprint early Na and/or Nasingle bondCa alteration. In northern Norrbotten, IOA deposits are characterized by early Na alteration evolving towards Nasingle bondCa alteration, then Fe-rich Casingle bondFe alteration. These hydrothermal alteration types are subsequently superimposed by later Ksingle bondFe alteration. We conclude that the use of Na-Ca-Fe-K-Mg molar barcodes provides new insights to understand the evolution of MIAC systems and is a powerful approach for unraveling superimposed alteration trends, which can serve as an exploration targeting tool from the district- to the deposit-scale in complex metasomatized area
Leaching and transport of PFAS from aqueous film-forming foam in porous media under saturated and unsaturated conditions: New insights from combining column experiments and reactive transport modelling
No full textInternational audiencePoly- and perfluoroalkyl substances (PFAS) have become significant emerging contaminants of concern due to their widespread presence in the environment and potential human health impacts. A major area of interest is understanding their fate and mobility in the environment. PFAS sorption depends on the molecular structure of the PFAS, the physical and chemical properties of the geomedia, and the chemical characteristics of the aqueous solution. A broad range of field and laboratory-scale experiments, as well as modeling efforts, have been conducted to quantify the mobility of an increasing number of PFAS in various porous media. However, most of these studies have used artificial solutions containing a limited number of PFAS, mainly PFOA and PFOS, which do not fully capture the real complexity of actual emission sources, such as aqueous film-forming foam (AFFF). Therefore, these results are difficult to apply for predicting the spatial and temporal extent of PFAS in real contaminated sites. This study aims to accurately assess the mobility of PFAS contained in AFFF in porous media by combining column experiments and reactive transport models. Column experiments were conducted with an AFFF containing mainly 6:2 FTAB, 6:2 FTS, and 6:2 FTSAam, along with smaller amounts of other PFAS. These experiments were performed on a man made sandy geomedia containing clay and organic matter, under both saturated and unsaturated conditions. For each saturation condition, two stages were conducted: the injection of diluted AFFF for 6 pore volumes, followed by the injection of a free-PFAS input solution for 7 pore volumes. A CaCl2 solution (10^-2 M) was used as the background electrolyte. Two AFFF dilutions were used for the input solution: a "low" dilution to ensure high PFAS concentrations (the concentration of the most abundant PFAS was 5 mg/L) and a "high" dilution representing diffuse contamination conditions (the concentration of the most abundant PFAS was 5 µg/L). Before the PFAS injection, a non-reactive tracer was injected to characterize the solute transport properties of the geomedia. A 1D multicomponent reactive transport model was developed to account for variably saturated/saturated flow, advection-dispersion, rate-limited diffusive transfer between mobile immobile domains, and thermodynamic equilibrium and/or kinetically constrained sorption reactions at the solid-water interface (SWI) and air-water interface (AWI). At low AFFF dilution, PFAS sorption was similar under both unsaturated and saturated conditions. Sorption varied according to the molecular structure of the PFAS. 6:2 FTAB and 6:2 FTSAam, which exhibit higher hydrophobicity and longer carbon chains, were strongly sorbed, while the breakthrough curve for 6:2 FTSA was close to that of the non-reactive tracer. These two former PFAS can be assumed to sorb onto clay minerals and organic matter. A comparison between unsaturated and saturated conditions highlighted that PFAS are mainly sorbed onto the surfaces of solid phases, and sorption at the AWI can be neglected. At high AFFF dilution, both saturation conditions and PFAS molecular structure influenced their mobility. For 6:2 FTSA, sorption was greater under unsaturated conditions than under saturated conditions, suggesting that sorption processes at the AWI play a key role at environmental PFAS concentrations. Since almost all the injected 6:2 FTAB and 6:2 FTSAam were sorbed in both saturation conditions, partitioning between AWI and SWI could not be distinguished. The entire set of PFAS breakthrough curves was accurately simulated. Simulation results showed that the amounts of PFAS sorbed at the SWI and AWI remained low compared to the amounts in the aqueous phase at low AFFF dilution. PFAS mobility was controlled by flow rate, dispersivity, and transfer between mobile-immobile domains. Under high AFFF dilution, the amount of sorbed PFAS onto SWI in saturated conditions, and at both SWI and AWI in unsaturated conditions, largely exceeded the PFAS concentration in the pore solution. Model calibration also highlighted that non linear and non-ideal equations must be used to simulate sorption processes onto SWI and AWI, suggesting the need for a numerical formalism more complex than linear isotherms. This trend was more pronounced for 6:2 FTAB and 6:2 FTSAam. The results reported here emphasize the value of conducting an integrated set of column experiments to refine the understanding of PFAS mobility in variably saturated porous media contaminated by AFFF and to better assess PFAS contamination in real-contaminated site
Lithium mines ores and concentrates traceability using portative XRF instruments
No full textInternational audienceTraceability of mineral raw materials is a highly topical issue for today’s society, and the impact of this industry can no longer be ignored. Environmental and social issues, as well as supply shortage and geopolitical concerns are rising the need to trace the origin of primary materials to encourage and promote a more sustainable production.Lithium is critical for the energy transition as it is used in most energy storage devices, in particular for electric vehicles. Lithium-Ion batteries (LiBs) are for now the only plausible alternative to fossil fuels engines, responsible of a consequent part of greenhouse gases emissions and air pollution.LiBs traceability is requested by the sector and policies for aforementioned concerns but is challenging due to the multiple process steps and ownership changes from the mine to the end product. Several solutions are being studied, based on digital technologies.However, it is key to develop geochemical intrinsic traceability of lithium along battery supply chain, to understand and prevent possible frauds: falsification of the declared origins and material mixings. In this regard, lithium isotopy can be used to verify the origin of a given material1 but is both expensive and time consuming. Analyzing the production of a mine plant site or incoming concentrate samples into a lithium refinery to verify the origin and check for anomalies requires fast and easy to set-up instruments.In this regard, the potential of portable X-Ray Fluorescence (pXRF) devices is investigated in this work by analyzing lithium ore and concentrate samples from lithium hard rock mines around the world. Two handheld pXRF and a portable Energy Dispersive XRF instrument were used and compared in terms of capability, precision and practicability. The effects on results of sample preparation and analytical parameters were studied. Results are also compared to ICP-MS analysis. Both classical data treatments and more advanced ones like machine learning have been in use.The results suggest that it is possible to differentiate deposit origins using on-site XRF instruments and the possibility to determine the provenance of materials of unknown origins. This study is part of EU-funded "MaDiTraCe" project.[1] Desaulty, AM., Monfort Climent, D., Lefebvre, G. et al. Tracing the origin of lithium in Li-ion batteries using lithium isotopes. Nat Commun 13, 4172 (2022)
Optimization of high-resolution hyperspectral data processing for the description of drill cores
No full textInternational audienceExploring ground resources has become challenging as the need for raw materials or for characterization of underground pollution has increased. Hyperspectral imaging of drill cores has been gaining popularity, especially in mining field, as it allows a fast and reliable estimation of mineral distribution1. However, with the increasing resolution of hyperspectral images, the size of the datasets (> 1 Tb) to process is exploding, impairing the capacity of the mineral mapping algorithms to work in near real-time2.The Sonic On-Line Sampling & Analysis (SOLSA) is a combination of sonic drilling and automated mobile analyses that highlights multiple insights of the ore body knowledge, on site and in real-time, to aid in the exploration, mining processing and decision-making (https://solsa-dem-up.eu/en). Chemical and mineralogical information is provided by profilometric, X-ray fluorescence (XRF), RGB and hyperspectral (HSI) sensors.To ensure runtimes compliant with the operational requirements, we develop a framework allowing to reduce the computational cost of hyperspectral images processing of a drill-core and to generate mineral maps. It embeds different algorithms for hyperspectral data pre-processing, spectral and spatial reductions as well as mineral matching. These last two treatments heavily rely on similarity metrics (i.e., clustering). Finally, comparisons with chemical and roughness data of the other devices are also proposed to refine the location of ore deposits.We demonstrate the capabilities of this framework to generate reliable and precise maps by processing a 10-meter core sampled at the closed tin mining site located in Abbaretz (France).References1Thiele et al., (2021), Ore Geology Reviews 136, 104252 : https://doi.org/10.1016/j.oregeorev.2021.1042522 Jacq et al., (2022), Quaternary 5(28) : https://doi.org/10.3390/quat502002
Étude du transfert des nitrates dans la zone non saturée des aires d’alimentation des captages AEP de Ligaine (Deux-sèvres)
No full textInternational audienceTwo groundwater catchments in Ligaine (north of Deux-Sèvres, France) are exploited for drinking water supplying of 54 municipalities in the North of Deux-Sèvres (western France).A hydrogeological assessment carried out in 2015 as part of the revision of the protection perimeters of the catchments highlighted an excess of nitrates (> 100 mg/L) in the raw water of the two catchments and requested specific investigations.An evaluation of nitrates stocks still present in the unsaturated zone and transfer rates, was performed to anticipate nitrates trends over the coming years. Indeed, the existence of a stock solutes (nitrates, phytosanitary products) in the unsaturated zone and aquifers necessarily leads to a delay between the implementation of water quality recovery programs and their effects</p
Biometeorological feedbacks on peatlands: Raising the water table to reduce meteorologically-related stress on cattle
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Using Pleiades Satellite Imagery to Monitor Multi-Annual Coastal Dune Morphological Changes
No full textInternational audienceIn the context of sea levels rising, monitoring spatial and temporal topographic changes along coastal dunes is crucial to understand their dynamics since they represent natural barriers against coastal flooding and large sources of sediment that can mitigate coastal erosion. Different technologies are currently used to monitor coastal dune topographic changes (GNSS, UAV, airborne LiDAR, etc.). Satellites recently emerged as a new source of topographic data by providing high-resolution images with a rather short revisit time at the global scale. Stereoscopic or tri-stereoscopic acquisition of some of these images enables the creation of 3D models using stereophotogrammetry methods. Here, the Ames Stereo Pipeline was used to produce digital elevation models (DEMs) from tri-stereo panchromatic and high-resolution Pleiades images along three 19 km long stretches of coastal dunes in SW France. The vertical errors of the Pleiades-derived DEMs were assessed by comparing them with DEMs produced from airborne LiDAR data collected a few months apart from the Pleiades images in 2017 and 2021 at the same three study sites. Results showed that the Pleiades-derived DEMs could reproduce the overall dune topography well, with averaged root mean square errors that ranged from 0.5 to 1.1 m for the six sets of tri-stereo images. The differences between DEMs also showed that Pleiades images can be used to monitor multi-annual coastal dune morphological changes. Strong erosion and accretion patterns over spatial scales ranging from hundreds of meters (e.g., blowouts) to tens of kilometers (e.g., dune retreat) were captured well, and allowed to quantify changes with reasonable errors (30%). Furthermore, relatively small averaged root mean square errors (0.63 m) can be obtained with a limited number of field-collected elevation points (five ground control points) to perform a simple vertical correction on the generated Pleiades DEMs. Among different potential sources of errors, shadow areas due to the steepness of the dune stoss slope and crest, along with planimetric errors that can also occur due to the steepness of the terrain, remain the major causes of errors still limiting accurate enough volumetric change assessment. However, ongoing improvements on the stereo matching algorithms and spatial resolution of the satellite sensors (e.g., Pleiades Neo) highlight the growing potential of Pleiades images as a cost-effective alternative to other mapping techniques of coastal dune topography