Rare metals (e.g. Li, Ta, Sn) are critical components for the renewable energy technologies. In Europe, a significant part of the resources issues from rare-metal granites and pegmatites (RMPG), especially those known in the Variscan belt remnants, such as the French Massif Central (FMC) and Iberian Massif. In order to achieve the green high-technology revolution, a sustainable European supply of Li and Ta needs the exploitation of the European RMPG deposits. However, the economic, environmental and societal impacts of such exploitation must be clarified. Furthermore, the geological processes involved in the genesis of such peculiar magmatic rocks and their extreme metal enrichment, e.g. the metallogenic model, remain poorly understood. This makes difficult the prediction of favourable areas for new discoveries. The TRANSFAIR project is a stimulating consortium that gathers a transdisciplinary expertise from geosciences to human sciences. It will provide a comprehensive metallogenic model for RMPG, enhancing district to deposit-scale mineral prospectivity mapping. To reach these objectives, TRANSFAIR will rely on two typical examples known in the FMC and Iberia, common learning fields for all the project activities. Based on recent results, TRANSFAIR propose to study the hypothesis of the RMPG origin from partial melting of Li-rich sedimentary source(s), combining innovative melting experiments and the characterization of natural objects following several approaches (petrology, geochemistry and geochronology). Ascent and emplacement processes, key parameters to explain the locations of the deposits, will be better constrained thanks to a coupled work of experimental petrology and numerical modelling. These results will be compared to natural case studies by a 3D understanding of the tectonic and structural contexts of ascent and emplacement of the deposits, reached by the acquisition of new geophysical and field data. Geochemistry (including stable and radiogenic isotope systematics) and geochronology will draw a better knowledge of the magmatic history of RMPG fields, from partial melting to emplacement of barren rocks and ore deposits. The integration of all these results will build predictive maps of favourable areas for RMPG. In the context of a significant increase of the needs for Li, which will lead to a strong increase of mining activities. TRANSFAIR will also draw the sociologic, economic benefits and disadvantages of new operations of RMPG in Europe and the strategy for societal engagement for renewed mining activities in Europe. Thus, TRANSFAIR will decipher the economic parameters linked to the valorisation of European RMPG by an econometric approach. Based on life cycle analysis, environmental impacts of these domestic operations will be compared to the actual global market. At last, levels of potential acceptability of mining projects in France, Portugal and Spain will be evaluated determining the concerned territories profiles, mapping stakeholders and adapting the social risk index. Simultaneously, TRANSFAIR will assess imaginaries linked to lithium, actually essential for the energy transition, making the link with the cartography of the geological potential issued from the project. As an answer to the actual needs of critical metals, TRANSFAIR will bring solutions towards better knowledge and valorisation of the European potential of RMPG, giving the keys both for a more efficient exploration, but also the bases for a better understanding between all stakeholders (citizens, public institutions and industries).

Beyond their role in artistic creation and symbolic expression of prehistoric societies, colouring materials were involved in different kind of activities related to technical and subsistence practices. The analytical developments of recent years, founded on the combination of naturalist (geology/ petrography) and archaeometric (mineralogical and elemental analysis) approaches, have provided a better understanding of the nature of these materials and allowed to investigate their geological origin. However, the application of these studies remains rare, even if colouring materials constitute an important potential of information for the understanding of technical and cultural behaviours, and the circulation of people and materials. There are several reasons for this scarcity of applications: 1/ the lack of knowledge about the evolutionary chains, i.e. the modifications of their characteristics due to bio-geochemical, anthropic and taphonomic transformations that occur from the deposit to their discovery: these modifications of their composition constitute biases that can limit the identification of the geological and geographical origin of the colouring materials; 2/ the diversity of the analytical protocols and the heterogeneity of data produced between laboratories and research teams: these biases limit the comparison of data between studies and limit the generalisation of these approaches; 3/ the difficulty of analysing and comparing the composition of blocks of colouring matter with that of residues on the surface of archaeological remains: while the protocols for analysing cohesive blocks are efficient and hardly invasive, the analysis of residues remains difficult and the analytical techniques used on the blocks do not provide the necessary spatial resolution for analysing these thin layers; 4/ the lack of robust geological references: the establishment of geological references at a regional or supra-regional scale requires considerable investment. The geological reference collections, established independently by researchers or teams as a result of projects centred on archaeological sites, are not easily accessible and reusable, notably because of standardisation issues. The objective of the Color-Sources project is to overcome these constraints in order to provide a new dynamic to the study of the origins of prehistoric colouring materials at a national and international scale, by developing and sharing knowledges and methodologies necessary to build geological reference collections and to compare them with archaeological collections. This objective will be achieved by developing an "open science" dynamic and the production of "FAIR" (Easy to Find, Accessible, Interoperable, Reusable) data. To this aim, Color-Sources will be supported by an interdisciplinary consortium in order a) to share the experience acquired in our various archaeological fields in order to better understand the evolutionary chains, to develop a common methodology for studying colouring materials and to implement it in a common field: the Dordogne and its periphery; b) to develop interoperable data acquisition protocols, to improve the statistical processing protocols for the data produced (particularly elementary data), and to develop an elementary analysis methodology by LA-ICP-MS/MS that could be applied to both blocks and residues of colouring materials in order to limit the biases induced by the use of several different techniques, c) to design an information system to save, reuse and disseminate the data acquired by the French community on the sources of raw colouring materials used in the Palaeolithic period.

Artificial fallout radionuclides from nuclear weapons testing and, more locally, from nuclear power plant accidents are found ubiquitously in the environment around the world and they provide the privileged marker candidates (“golden spikes”) of the Anthropocene stratigraphic layers. The onset of their emissions coincided with the period of Great Acceleration that took place after World War II and that is characterized by an increase in soil degradation, which was mostly triggered by land use change. Particle-bound radiocaesium and plutonium are widely used to date modern sediment archives and reconstruct soil redistribution rates during this period. However, the fallout chronology is better constrained in the Northern Hemisphere, and much less is known regarding the timing and the spatial distribution of their deposition in the Southern Hemisphere. The Franco-Swiss AVATAR project consortium will therefore fill this important knowledge gap through the compilation of all data available in the literature and in recently released declassified military archives. Our main objectives are to (i) provide the first detailed reference map for land surface in the Southern Hemisphere of both 137Cs and 239+240Pu fallout and the associated uncertainties, (ii) disentangle – through the use of rigorous end-member un-mixing models – fission product signatures of 137Cs and Pu isotopic ratios, which depend on the different atmospheric nuclear tests conducted near the Equator and in the Southern Hemisphere and (iii) to apply the refined baseline data to reconstruct on-site soil erosion rates, validating soil erosion modelling assessments and dating of environmental archives during the Anthropocene in the Southern Hemisphere. Based on a comprehensive literature survey, we will conduct soil and sediment sampling in zones identified as data gaps, analyze these samples for cesium and plutonium to calculate their fallout radionuclide inventories and sources (i.e. the proportion of global fallout due to USSR and USA atmospheric nuclear bomb tests with a peak in 1963 vs. the proportion of fallout due to French nuclear tests conducted between 1966 and 1974 in the South Pacific). Spatial analyses will be conducted to provide the first reference map of radiocesium and plutonium fallout in the southern hemisphere and to improve sediment core dating through the incorporation of additional time markers related to the late French atmospheric bomb tests (1966-1974). The improved fallout distribution knowledge over space and time will be used to reconstruct soil redistribution during the Anthropocene through an innovative combination of conversion and erosion models in two pilot large river basins of the southern hemisphere. We selected the Uruguay River basin in Brazil/Uruguay/Argentina, and the Piura/Catamayo River basin in Ecuador/Peru where we have preliminary experience and knowledge on FRN distribution and erosion modelling. The AVATAR project will propose original methods to validate the spatial and the temporal distribution of sediment transfer reconstructions in these large river basins during the Anthropocene. Finally, the compiled databases and maps will be shared with a wide community including atmosphere scientists, climatologists, radio-toxicologists and soil scientists. A participative network to update and upgrade a fallout radionuclide database at the global scale will be launched at the end of the project.

Chemical weathering is a central biogeochemical process that shapes the Earth’s Critical Zone (CZ), regulates the global carbon cycle and sets the pace for nutrient delivery to soils and ecosystems. Most knowledge on the rates and controls on chemical weathering are from laboratory experiments and from the short-term observation of modern soil and river systems. In contrast, little is known about past changes of chemical weathering over hundreds to thousands of years, which limits our understanding of how long-lasting human-climate-ecosystem interactions have impacted the CZ trajectories. Because of this knowledge gap, it is not possible to fully understand the response and feedbacks of the CZ to the climatic and environmental perturbations of the Holocene period, nor to predict their future evolution during the Anthropocene. To fill this gap, LAKE-SWITCH aims to produce new quantitative weathering records over 10^2-10^4 year timescales, with a temporal focus on the Holocene period. There are 3 main challenges: 1) developing quantitative proxies of chemical weathering, 2) calibrating these proxies for paleo-reconstructions, 3) measuring these proxies in paleo-archives of 10^2-10^4 year timescale integration. To provide these records, we will measure lithium and strontium isotopic proxies in lake detrital and authigenic – carbonates and biogenic silica – sediment archives. To calibrate these proxies and archives, we will use a source-to-sink approach and track weathering product pathways from soils, through rivers, to lake deposits. Then we will apply these proxies back in time in Holocene lake cores. As rapidly-eroding mountain dominate the global chemical erosion budget, we will focus on the study of the European Alps. New data from Alpine watersheds and lake records spanning gradients in erosion, runoff and land use will serve to quantify and model the impact of climate and human drivers on soil trajectories from the onset of the Holocene to the Anthropocene.

The aim of the HUNIWERS project is dual: i) to use urban speleothems and “classical” archives to determine and compare the past and current quality and availability of groundwaters (water table but also infiltrating diffuse water) in the Paris conurbation in order to identify the sources and spread of pollutants; ii) evaluate the state/quality of the perched aquifers, evaluate the efficiency of environmental policies (impacts on pollutant sources) and evaluate, in relation with public authorities and stakeholders, the possible use of these waters as alternative water supply. The impact of urban development on water resources is a major issue. It is particularly acute for near surface urban groundwater. In Paris, these groundwater, once providing drinking water, are now disused. Understanding their present and past chemical status would be extremely useful to assess past public remediation policies and to open discussion for their use as non-conventional water resource. Determining urbanization/industrialization impacts on water quality is hampered by two majors scientific locks: i) knowing the initial (pre-urbanization) state; ii) identifying key elements and natural archives suitable to reconstruct pollution sources and levels through time. Over the past 5 years, we have developed a pioneer approach to reconstruct the past evolution of groundwater quality in urban environments. By coupling the analysis of “urban speleothems” (calcareous crusts) formed in a historical underground aqueduct with today’s water analysis, we obtained a 300 years record of selected chemical pollutant (lead, sulfur, rare earth elements) in a small watershed of NE Paris and identified today’s pollution sources but also back in the 18th century. With the HUNIWERS project, we propose to apply and extend this dual and innovative approach to the city of Paris and its conurbation in order to (1) reconstruct the origin and the quality of past groundwater by using urban speleothems in different undergrounds and (2) compare past and current quality and availability of groundwater table and infiltrating diffuse water. The HUNIWERS consortium involves 41 staffs from 7 main partners: LSCE, CRPG, ISTO, EDYTEM, GEOPS (cutting edge laboratories involved in environmental research) but also Cerema (a governmental scientific and technical resource center with a strong regional integration) and HT2S/CNAM (relation between science-technology and society). The main objectives of HUNIWERS are organized in 5 tasks: : 1) Hydrological cycle modelling in 2 contrasted Parisian watersheds: water budget and comparison between land use, outflow and climatic data (measurement and historical archives) 2) Characterize the current groundwater physico-chemistry; 3) Obtaining time series of the geochemical evolution of past water geochemistry using speleothems in different sites; 4) Determine the sources and mechanisms of pollutant transfer today and in the past; 5) explore the possibilities for the re-use of sub-surface waters from Oligocene strata, as alternative water supply. HUNIWERS combines a highly innovative approach (we are the only group to use urban speleothems worldwide) with a relatively low risk, because we have already used the methodology on smaller - and now completed - investigations HUNIWERS’ outputs include fundamental aspects such as the legacy of human activities in the urban environment and the perspective to assess the impact of urban and industrial development and public remediation policies. HUNIWERS will also intend to develop operational tools for water management such as: - heavy metal and organic pollution mapping to determine the most sensitive groundwaters; - assessment on whether subsurface groundwaters are suitable for “non-conventional” uses; - geochemical tools for establishing, the presence of leakages from the networks. Extending the HUNIWERS methodology to other European cities will pave the way for a participation to the H2020 call.