Planetary atmospheres are fundamental reservoirs controlling the habitability of planets. The chemical and isotopic compositions of atmospheric constituents also hold clues on the geological evolution of the entire planetary body. Today, the terrestrial atmosphere contains about 80% dinitrogen and 20% dioxygen. Yet, there is no scientific consensus on how and why these two molecules emerged and persisted in the Earth's atmosphere. The interactions between the atmosphere and the continental crust also play a major role in controlling the bio-availability of nutrients and the composition of the atmosphere, and thus the climate. However, the evolution of the volume of continental crust over time is strongly debated. Project ATTRACTE will significantly improve our knowledge of the main drivers of atmospheric evolution over time. This will be achieved by going back in time and following the evolution of the composition of the Earth's atmosphere over geological eons. Analyses of gases contained in traditional and new paleo-atmospheric proxies, the post-impact hydrothermal minerals, will be carried out with innovative mass spectrometry techniques. The isotopic composition of paleo-atmospheric xenon will provide new constraints on the history of hydrogen escape for the Archean Earth. Coupled argon and nitrogen measurements will allow to determine, for the first time, the evolution of the partial pressure of atmospheric dinitrogen. Paleo-atmospheric data gathered during the project will be fed in numerical models of Earth's atmospheric and crustal evolution. This will allow to reconstruct how volatile elements have been exchanged between the silicate Earth and the atmosphere through time. Results gathered during project ATTRACTE will ultimately provide a new dataset for climate studies of the ancient Earth but will also help building the scientific framework required to interpret future observations of exoplanetary atmospheres and to portray the geology of extrasolar planets.

The deep carbon cycle is the recycling of carbon toward the deep Earth, i.e., mantle and core. Preventing all of the Earth's carbon from entering the atmosphere, it maintains suitable conditions for life existence. In the modern Earth, the transfer of carbon from surface to depth is limited to subduction zones, where the oceanic lithosphere is recycled into the mantle. It has long been considered that most of the subducting carbon was inorganic (in the form of solid carbonates), which abundance largely exceeds the quantities of organic carbon of biological origin trapped in seafloor sediments. However, the recent years have seen considerable changes in deep carbon cycle paradigms, with notably the first thermodynamic evidences for abiotic synthesis of organics at high pressure at plate boundaries. These new models suggest that organic carbon may represent an important, although largely unconstrained, fraction of carbon in the deep Earth. The CARBioNic project aims at revisiting the deep organic carbon cycle by exploring the mechanisms of abiotic organic carbon synthesis in subduction zones. To achieve this goal, the PI will characterize the diversity of organic materials that can be preserved and/or formed in high pressure natural samples from Western Alps meta-ophiolites by implementing new tools of rock-hosted carbon characterization from micro- to nano- scales at the Institut de physique du globe de Paris. The mechanism of abiotic carbon synthesis, their stability and potential link with organic minerals and diamonds will be explored through a series of high-pressure experiments involving synthetic organic compounds over a large range of pressure (3-10 GPa) and temperature (500-100°C). The mobility of organic carbon in metamorphic fluids at high pressure will be determine using a combination of bulk rock and in situ stable isotope analyses (?13C). These results will be used to quantify and compare the efficiency of organic versus inorganic carbon recycling in the deep mantle.

Phreatic or hydrothermal eruptions are relatively frequent phenomena on active volcanoes hosting shallow hydrothermal systems, where heat and fluids are transferred from the magmatic source to the surface through a porous and fractured rock. Such a flow of fluids promotes the increase of interstitial pressure as well as the alteration and weakening of the host rock, potentially leading to conditions of mechanical failure. The deriving phreatic explosions are able to generate jets of gas and particles, often accompanied by intense fallout of large (10-40 cm) lithic blocks. Due to the complex interaction of the magmatic and hydrothermal systems, phreatic explosions are among the most sudden and unpredictable volcanic phenomena. Their study is hindered by the largely incomplete stratigraphic record, the partial understanding of the underlying physical processes, and by the fact that such eruptions often manifest few, low-amplitude and unclear precursors in geophysical and geochemical signals. This project aims to develop a new physical and numerical model for the simulation of phreatic eruptions, and to apply it to the estimate of volcanic hazard and risk at La Soufrière de Guadeloupe (Lesser Antilles, FR), where the recent unrest episodes have increased the alert level for the resident population and for tourists, who increasingly visit the volcanic area. The project will focus on 1) aspects related to establishment and stability of initial conditions in the porous and fractured environment hosting the hydrothermal system; 2) the role of liquid water in the explosion, involving the explosive phase transition (flashing) of overheated water; 3) the 3D simulation of the phreatic explosion dynamics, with focus on potential blast generation and ballistic ejection. The scientific objective is to better understand the mechanism that triggers the explosion of the hydrothermal system under forcing by a deep magmatic source and to predict its dangerous effects.

In the context of the Earth's global warming, the fragile equilibrium between cryosphere, ocean and biology that exists in Antarctica is at risk. The ice sheet covering most of the continent retains more than 80% of fresh water on Earth and its melting would generate a 60-meter sea-level rise. Ocean not only plays a key role in the global warming but is also a major contributor in the melting of the Antarctic floating ice. Antarctic coastal regions host very rich and diverse ecosystems but represent also places where living organisms have developed extreme adaptation to face the most extreme conditions on our planet. In these area, any environmental change will have major consequences on biological populations, on the ecological equilibrium, and on the trophic chain, from the krill to the large mammals. In order to better understand the close and complex relationship between cryosphere, ocean and life in Antarctica and to foresee future consequences of the current climate changes on sea level, ecosystems and ocean circulation, we propose to build a strong and multidisciplinary scientific consortium (Geophysics, Oceanography and Biology-Ecology) working toward the objective of submitting an ambitious program to the 2019 ERC-SYNERGY call. Our program, called ICEOLIA (Ice - Ocean - Life Interplay in Antarctica) will focus on Terre Adélie and George V Land coastal areas. It will be built around three interdependent topics namely the ice, the ocean and the Antarctic ecosystems and will combine seismic, oceanographic and bio-acoustic observations to monitor: i) the ice activity using land and ocean-bottom cryo-seismic observations, ii) the physical and biological oceanography parameters and in particular the influence of the sea-ice development on the local ecology and on the food web, and iii) the ecology of the large mammals in a poorly known region and their behaviour in their changing environment, using bio-acoustic recording. This region is of particular interest because: i) it presents typical land-to-sea ice outflow via small to large glacial outlets draining a large portion of a major ice basin of East Antarctica (Wilkes Subglacial Basin). With a rock basement below sea level, it is particularly vulnerable to marine warming and the ice sheet instability may significantly contribute to sea level rise; ii) it corresponds to a region poorly studied and instrumented by geophysics compared to West Antarctica, but it has been the locus of oceanography and marine experiments, and iii) the presence of the Dumont d'Urville French polar base will provide a key logistical platform to make this project successful. The Astrolabe supply and research vessel also represents a key vector to explore and instrument the Terre Adélie coastal areas, and also potentially the neighbouring George V and Wilkes lands. From its multidisciplinary approach, this project is particularly well suited to build up a ground-breaking ERC-SYNERGY proposal. The present MRSEI proposal will support our group in exchanging, in sharing and in meeting together to mull the project over, build and prepare it for the submission in November 2019.

In GPX Paris, two world class research and teaching institutes in Earth Science, Institut de Physique du Globe de Paris (IPGP) and French Grande Ecole, Ecole des Mines de Paris (Mines ParisTech), propose to create a world-class group in the field of exploration geophysics in Paris in partnership with the leading French geophysical companies, CGGVeritas and TOTAL. The project also involves the Indian Institute of Technology Madras, one of the top engineering institutes in India. The main objective of this project is to create an international level Master of Research in Exploration Geophysics, attracting the best students from France and around the world and retaining them for research through Ph.D. program. The project will consist of two complementary parts: (1) Master of Research in Exploration Geophysics (MREG) and (2) research on quantitative imaging using coupled seismic and electromagnetic methods training Ph.D. students. The MREG program will consist of taught courses, several weeks of hands-on training in the field (land and marine) and in companies, and research stage relevant to industry at the partner institutions. We propose to take 10 students each year. The best of these graduating students will be offered Ph.D. fellowships to carry on doing industrial research in exploration geophysics. The IPGP will be the host institution. Together with the Mines ParisTech group, it will prepare and implement a new advanced curriculum in Exploration Geophysics in close cooperation with industrial partners. The two core institutions will actively participate both in teaching and research. IPGP has decided to create a new Department of Exploration Geophysics (DEG) and to recruit several new scientists to develop GPX Paris and enhance the partnership with industry. It has also decided to create Associate Professorships for colleagues from Industry who will actively participate in the GPX Paris project. The IPGP new purpose-built building at rue Curvier with a state of the art lecture rooms, research and computing facilities is an ideal site for developing a new research and training project. TOTAL and CGGVeritas will be the industry partners. They each will contribute 300,000 euros for four years. Leading scientists from these companies will take-up Associate Professorships at IPG Paris and will allocate 10-20% of their time to the GPX Paris project. CGGVeritas will provide a week of training at its centre in Massy to the Master Students in data acquisition and processing. Both TOTAL and CGGVeritas will host Master and Ph.D. students at their research centres and will actively participate in their supervisions. Professor Satish Singh, an eminent scientist, will be Head of the DEG and will lead the GPX Paris project. He will work closely with colleagues from IPGP and Mines ParisTech in designing the courses, teaching and supervising the students. A Management Committee, consisting of members from all partners will meet every three months and will direct the project. Teaching Committee will supervise and follow teaching program. A Scientific Advisory Board, consisting of scientists from other French institutions and partners will meet once a year and advise the Management Team. The total cost of the project is 1,200,000 euros, of which 600,000 euros will be funded by the industry partners and we request 607,000 euros from the ANR.