Recent signatures of feldspar minerals in Mars VNIR spectroscopic data raise questions about the origin of the host rocks and about the true nature of Mars earliest crust. These detections could indicate the presence of anorthositic rocks from a floatation crust, or felsic remnants of a continental crust. The nature of the feldspar-bearing rocks remains enigmatic due to numerous uncertainties regarding the effect of feldspar composition and grain size/ textures/mineral assemblages on the final rock spectrum. The present project aims at investigating Mars crust composition by improving the analysis of Mars remote sensing data and combining it with laboratory investigations of the VNIR properties of a range of fully characterized, potential analog, terrestrial feldspathic rocks. Additional fieldwork at key analog sites and spectral modeling will allow us to further discuss the influence of the scale of observations and relate the spectral signature of a rock to its composition and texture. A unique reference library, acquired on whole rocks, will be generated through the MARS-Spec project, and publicly shared with the science community via the CRPG “Mirabelle” database. In turn, the project should shed light on the nature of the feldspar detections, their implication for Mars magmatic history, but will also impact future exploration of Mars by orbiters and rovers.

Chondrites are solid remnants of the formation of the solar system 4.56 Ga ago. They provide a direct glimpse into the astrophysical conditions under which the Sun was formed and into the dynamics and evolution of the accretion disk. After their formation however, chondrites experienced secondary fluid alteration that caused important changes to their textures, mineralogy, and chemical and isotopic compositions. Even though it is widely acknowledged that chondrites underwent this secondary modification, the physicochemical conditions under which it took place and the timing and duration of the alteration process are still only partially understood. This gap in our understanding severely restricts interpretation of meteorite data. In view of the multi-faceted complexity of the problem, three young researchers, specialists in cosmochemistry, terrestrial alteration, fluid-rock interactions and thermodynamics, have been brought together in order to merge their respective skills and resources and create a highly capable scientific team with which to tackle this issue. Two groups of chondrites will be used as a common theme in this project. These are thought to represent the two main types of fluid alteration that occurred on asteroidal parent bodies: (i) low temperature hydrothermal alteration (CM group) and (ii) fluid-assisted metamorphism (CV group). Within these groups, specific minerals (olivines and carbonates) and mineral associations (tochilinite/cronstedtite associations and fayalitic-magnetite-troilite veins) will serve as probes with which to address fundamental first-order questions on the alteration processes: What were the compositions of the fluids that affected primitive chondrites? Under what physico-chemical conditions did alteration take place? How long did the alteration process last in the early Solar System? Finally, and more generally, what is the intrinsic role of secondary alteration processes in establishing chondrite characteristics? Resolving these questions would provide us with important constraints on the types of geological activity experienced by asteroids and on the links between the diversity of meteorite groups and the diversity of asteroids. In addition, understanding the nature of the alteration fluids could help to decipher the spatial distribution of water in the early Solar System and the conditions under which water was delivered to Earth. The strength of the SAPINS project lies in a multidisciplinary approach that combines the analytical, experimental and thermodynamic modeling expertise of three young researchers – a team that is therefore equipped with the multiple skills needed to attack a problem such as this. In addition, SAPINS will apply powerful analytical and experimental instruments and techniques that have been developed on terrestrial rocks to the mineral assemblages observed in chondrites. On completion, this project will provide us with a new understanding of alteration conditions and processes in the early Solar System. This knowledge will be of key importance in the preparation and data interpretation of space missions devoted to the visit and/or sampling of hydrated celestial body surfaces (e.g. Rosetta, Dawn, OSIRIS-Rex, Hayabusa). ANR funding is essential for the undertaking of multidisciplinary research such as SAPINS as these projects require a combination of expertise, notably in the fields of petrography, geochemistry and experimental petrology for SAPINS. In summary, the SAPINS project will stimulate scientific advances by combining different disciplines and stimulating interaction among the different communities involved.

Hydrogen is the most abundant element in the solar system; nonetheless its distribution in the planetary solids remains poorly known and its origin on Earth and the other rocky planets enigmatic. HYDRaTE proposes to shed light on the distribution of hydrogen in the protoplanetary disk 4.56 billion years ago by studying the hydrogen-bearing phases of primitive solar system materials including primitive meteorites (chondrites), micrometeorites and dust particles retrieved from hydrated bodies by space missions. Conjugating the complementary skills of a team led by L. Piani at Centre de Recherches Pétrologiques et Géochimiques (CRPG) in Nancy and composed of lab managers, engineers, students, and of three external researchers, HYDRaTE will use a multifaceted approach to (i) estimate the hydrogen concentration and isotopic composition (D/H ratio) of H-bearing phases in extraterrestrial samples, (ii) experimentally determine the conditions in which hydrogen is incorporated in primordial dusts and, (iii) quantify the contribution of chondritic material to the hydrogen-budget of the Earth and other rocky planets. The project will benefit from the presence at CRPG of state-of-the-art analytical instruments and experimental devices. Among them, the Secondary Ion Mass Spectrometers (SIMS) Cameca IMS1280-HR equipped with the new Hyperion oxygen sources will be at the heart of the project allowing the in-situ analysis of hydrous and nominally anhydrous minerals. For the most hydrated samples, we will use a method based on in-situ measurements of the C/H and D/H ratios by SIMS to estimate the isotopic composition of water-bearing minerals. This method, recently developed by HYDRaTE's PI, allows for the first time the D/H ratios of hydrous chondritic minerals to be determined without hindrance from hydrogen in adjacent organic materials. Coupled with ion imaging for measuring the D/H composition of organic particles, this will permit an exhaustive assessment of the origin of volatile-rich molecules in primitive solar system materials. We will investigate the distribution of hydrogen in the major high-temperature components of chondrites, the chondrules, via laboratory experiments and analytical measurements. We will build an experimental device to melt and crystallize chondrule analogues under conditions close to those estimated for the protoplanetary disk (low total pressure, low oxygen fugacity) and high partial pressures of H2 and/or H2O. Through these experiments, we will study the consequences of the presence of hydrogen-rich gases on chondrule formation and provide for the first time thermodynamical data on hydrogen partitioning and isotopic fractionation under conditions close to those estimated for the protoplanetary disk. These experimental results will be compared to the hydrogen compositions of natural samples. Indeed, a major achievement of HYDRaTE will be to quantify the hydrogen abundance and isotopic composition of chondrule silicates, with particular focus on enstatite chondrites, the best candidate for the Earth's building blocks, and to estimate the contribution of the different categories of chondrites to the H budget of Earth and the other terrestrial planets.

Scientific rationale: Since the Earth surface is up to now the only viable place for humanity, it is critical to predict how it will respond to future climatic variations. This requires a good understanding of how past climate changes have affected continental surfaces. One of the key factors controlling the surface dynamic and the long-term climate is denudation (or erosion), i.e. the sum of physical erosion and chemical alteration. However, the impact of climatic variations on denudation during geological time remains poorly understood and controversial (Herman and Champagnac, 2016 vs Willenbring and Jerolmack, 2016). This is particularly critical regarding the impact of glacial-interglacial cycles on denudation. These climatic cycles affected the Earth with a rhythmicity of 100 kyr and temperature amplitudes of ca. 8°C (with significant regional disparities) during the last million of year. According to certain authors (e.g. Molnar, 2004; Herman et al., 2013), the apparition of these glacial fluctuations induced a major increase of denudation worldwide, while other scientists (e.g. Willenbring and von Blanckenburg, 2010) argue that these climatic changes had no effect on denudation. This controversy is in part due to methodological biases and to the fact that tectonics may hide the pure climate forcing on long time scales. To overcome this debate, there is a need of high-resolution data based on unequivocal proxies of denudation, applied to archives that precisely document the effect of glacial-interglacial cycles, independently from the tectonic forcing. In recent years, our CRPG research group has been a pioneer in showing that cosmogenic nuclides (e.g. 10Be) can be used as powerful geochemical tools to quantitatively reconstruct paleo-denudation rates over geological time scales. Goals of the project: In this project, we will study the impact of glacial-interglacial variations on erosion. To this end, we will quantify paleo-denudation rates using in situ10Be, a robust denudation proxy that is not affected by the same bias as other methods. Our effort will focus both on large glacial-interglacial cycles (100 kyr periods) and both on short-term millennial climatic fluctuations (Dansgaard-Oeschger events), using well-dated marine sedimentary records in contexts that have undergone major and variable changes in glacial extents. Over this time scale, the impact of uplift may safely be assumed as negligible. Secondary questions will also be addressed: what is the seasonal effect on the cosmogenic 10Be concentrations? What is the impact of the watershed size on the sediment transfer time? Does the sediment granulometry have a predictable effect on the cosmogenic nuclides concentrations in quartz? Material and methods: We will apply this approach on modern and ancient sediments of 3 Mediterranean river watersheds having different sizes, elevations and climatic characteristics: the Rhône (over a 0-25 ka period), the Var (0-70 ka) and the Golo (0-500 ka). Our approach will combine several complementary methods: (i) field geology to collect samples in modern watersheds, (ii) GIS (Geographical Information Systems) analysis of watershed, (iii) rock source tracking (e.g. Nd isotopes), iv) marine sedimentology, v) analysis of in situ cosmogenic 10Be, 26Al (and 14C) in quartz of cored sediments, vi) numerical modelling to constrain and classify the effects of several key parameters: equilibrium line altitude of glaciers, temperature, the amount and time repartition of rainfall, geology substratum, vegetation. Societal impacts of future results: Our ability of understanding the soil resilience to external climatic changes is crucial to anticipate the impact of global warming on the stability of the Critical Zone. This knowledge may have major implications on risk evaluation, urbanization and agricultural policies.

Refractory inclusions (Ca, Al-rich inclusions and amoeboid olivine aggregates) and chondrules found in primitive meteorites (chondrites) are ancient solids formed at high temperature during the first few millions years of the early Solar System. Because they are the buildings blocks of larger bodies, deciphering their origin, processes and timings of formation is of fundamental importance to understand the dynamical evolution of the young protoplanetary disk and the formation of planetary embryos. In spite of numerous studies and significant improvements during the last decades, the message carried by these solids is still not clearly understood and therefore the way these primordial solids and planetesimals formed remains very enigmatic and controversial. The CASSYSS project is an innovative and ambitious multidisciplinary project mixing petrological, cosmochemical, experimental and astrophysical approaches. Targeted object will be representative chondrules and refractory inclusions from least-altered chondrites from the carbonaceous, ordinary and enstatite groups. We have performed analytical developments allowing for the first time to study almost every kind of primordial objects, and thus to avoid sampling biases inherent to most studies. As a result, this project will provide the first accurate and unbiased chronology of formation coupled with a comprehensive petrographic, chemical and isotopic characterization of primordial solids. Thus we believe that the innovative and ambitious approach proposed in this project will produce results with first order implications in cosmochemistry, planetology and astrophysics.