Papers by Chrystele Sanloup
Frontiers in Earth Science, 2019
Frontiers in Earth Science, 2019
Our understanding of the deep carbon cycle has witnessed amazing advances in the last decade, inc... more Our understanding of the deep carbon cycle has witnessed amazing advances in the last decade, including the discovery of tetrahedrally coordinated high pressure (P) carbonate phases. However, little is known about the physical properties of their molten counterpart at moderate depths, while their properties at lower mantle conditions remain unexplored. Here, we report the structure and density of FeCO 3 melts and glasses from 44 to 110 GPa by means of in situ x-ray synchrotron diffraction, and ex situ Raman and x-ray Raman spectroscopies. Carbon is fully transformed to 4-fold coordination, a bond change recoverable at ambient P. While low P melts react with silica, resulting in the formation of silico-carbonate glasses, high P melts are not contaminated but still quench as glasses. Carbonate melts are therefore polymerized, highly viscous and poorly reacting with silicates in the lower mantle, in stark opposition with their low P properties.
Geochemistry, Geophysics, Geosystems, 2019
The Xe-SiO2 system is studied by in situ high pressure and temperature experiments and ab initio ... more The Xe-SiO2 system is studied by in situ high pressure and temperature experiments and ab initio calculations. • Xe is incorporated in quartz and a new (Xe,Si)O2 phase is identified. 1 • These findings emphasize the need to consider Xe storage in crust minerals in the framework of the 'missing xenon' issue.
Nature
Our understanding of atmosphere formation essentially relies on noble gases and their isotopes, x... more Our understanding of atmosphere formation essentially relies on noble gases and their isotopes, xenon (Xe) being a key tracer of the early planetary stages. A long standing issue however is the origin of atmospheric depletion in Xe 1 and its light isotopes for the Earth 2 and Mars 3. Here, we report that feldspar and olivine samples confined at high pressures (P) and high temperatures (T) with diluted Xe and krypton (Kr) in air or nitrogen are enriched in heavy Xe isotopes by +0.8 to +2.3‰ per a.m.u., and strongly enriched in Xe over Kr. The upper +2.3‰ per a.m.u. value is a minimum since quantitative trapping of unreacted Xe either in bubbles or adsorbed on the samples is likely. In the light of these results, we propose a scenario solving the missing Xe problem involving multiple events of magma ocean stage at the proto-planetary stage combined with atmospheric loss. Each of these events results in trapping Xe at depth and preferential retention of its heavy isotopes. In the case of the Earth, the heavy Xe fraction was later added to the secondary CI chondritic atmosphere through continental erosion and/or recycling of an Hadean felsic crust. Atmospheric Xe is elementally depleted by a factor of 24 relative to Kr in CI chondrites (Table 1), and isotopically depleted by 35 ‰ per a.m.u., which is known as the missing Xe problem 1. The loss of elemental Xe occurred very early on 4 (<100 My). Its isotopic fractionation in the terrestrial atmosphere is recorded continuously throughout the Archean 5 , a situation settled before 4 Gy for
mas are produced at depth in the Earth, and occurrences of their presence at greater depths are r... more mas are produced at depth in the Earth, and occurrences of their presence at greater depths are reported based on seismological information, such as the 410 discontinuity or atop the core-mantle boundary. Understanding the presence and eventual stability of magmas in the deep mantle requires a knowledge of their physical properties. However, this has been impeded for a long time due to the challenging nature of the experiments. In the recent years, structural and density information on silica glass have been obtained up to record pressures of up to 100 GPa, a first major step towards obtaining data on the molten state. Here, the structure of molten basalt is reported up to 60 GPa by means of in situ x-ray diffraction, and structural changes are evidenced. Silicon coordination increases from 4 at ambient conditions to 6 at 35 GPa, similarly to what has been reported in silica glass. Compressibility of the melt above completion of Si coordination change is lower than at lower pressure (P) conditions, implying that a single equation of state can not accurately describe density evolution of silicate melts over the whole mantle P-range. It also implies that melts can be buoyantly stable circa 35-40
This chapter describes how the structure of molten silicates under high pressures may be measured... more This chapter describes how the structure of molten silicates under high pressures may be measured by synchrotron X-ray diffraction, using either large-volume presses or diamond-anvil cells, the latter combined with resistive-heating or laser-heating techniques. A brief summary of the data obtained so far is given, followed by a description of both energy-dispersive and angle-dispersive techniques, including challenges and how they may be overcome. Three areas of research are then highlighted: (1) structural measurements at extreme pressure conditions up to 100 GPa, (2) tracking the structural environment of minor/trace elements in magmas, and (3) the different ways to obtain the density of melts from X-ray diffraction data. Finally, some future prospects are discussed.
A 2011 NASA study [1] of moonquakes, based on seismometer measurements made during the Apollo mis... more A 2011 NASA study [1] of moonquakes, based on seismometer measurements made during the Apollo missions, revealed a surprising new view of the lunar interior: the deepest parts of the rocky mantle of the Moon, at depths between 1200 and ~1350 km, appear to contain large amounts of molten rock (magma). In fact, up to 30 per cent of this deep layer may be molten. On Earth, such melt percentages would be accompanied by the formation of volcanoes, because magma formed in the interior of the Earth is less dense than the rock it originates from. This density difference provides a driving force for upward transport, leading to volcanic eruptions at the surface. However, despite the presence of large amounts of magma in its interior, the Moon has no active volcanoes. We have found an explanation for this apparent discrepancy by subjecting synthetic Moon rocks to extreme pressures and temperatures and measuring the density of the resulting magma using in situ techniques at beamline ID27.
Magmas Under Pressure, 2018
This chapter describes how X-ray structural measurements can be done on molten silicates under hi... more This chapter describes how X-ray structural measurements can be done on molten silicates under high pressures, using either large volume presses or diamond-anvil cells, the latter combined with resistive heating or laser heating techniques. A brief summary of the data obtained so far is given, followed by a description of both energy-dispersive and angle-dispersive techniques, including challenges and how they may be overcome. Three areas of research are then highlighted: 1) structural measurements at extreme pressure conditions up to 100 GPa, 2) tracking the structural environment of minor/trace elements in magmas, and 3) the different ways to obtain the density of melts from X-ray diffraction data. Finally, some future prospects are discussed.
Goldschmidt Abstracts, 2020
Acta Crystallographica Section A Foundations and Advances, 2019
Xenon (Xe) is the most reactive amongst noble gases, with over hundred compounds synthesised at a... more Xenon (Xe) is the most reactive amongst noble gases, with over hundred compounds synthesised at ambient pressure. Increasing pressure is an efficient way to induce Xe reactivity, especially with oxides, resulting in the formation of covalent Xe-O bonds. Some examples will be given, ranging from stoechiometric compounds to silicate minerals doped in Xe at the % level, the latter being stable at remarkably low P conditions. Xe reactivity with silicates extends to compressed magmas, molten materials that were also shown to react with krypton. The search for noble gases compounds has for long been fuelled for their high energy storage capacity, but implications in Earth's sciences are also large as the latter rely on noble gases to trace key planetary processes such as atmospheric formation or underground nuclear tests. Therefore, we will finally discuss the implications of heavy noble gases reactivity under P, i.e. at the conditions of planetary interiors, on isotopic fractionation.
Journal of Physics: Condensed Matter, 2018
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Frontiers in Physics, 2020
While the field of noble gas reactivity essentially belongs to chemistry, Earth and planetary sci... more While the field of noble gas reactivity essentially belongs to chemistry, Earth and planetary sciences have brought a different perspective to the field. Indeed, planetary interiors are natural high pressure (P) and high temperature (T) laboratories, where conditions exist where bonding of the heaviest noble gases may be induced thermodynamically through volume reduction (Le Châtelier's principle). Earth and planetary sciences besides generate numerous and precise observations such as the depletion of the terrestrial and martian atmospheres in xenon, pointing to the potential for Xe to be sequestered at depth, potentially induced by its reactivity. More generally, this paper will review the advances on noble gas reactivity at the extreme P-T conditions found within planetary interiors from experiments and theoretical investigations. This review will cover the synthesis of cage compounds, stoichiometric oxides and metals, and non-stoichiometric compounds where noble gases are only minor or trace elements but could be essential in solving some Earth and planetary puzzles. An apparent trend in noble gas reactivity with P emerges. In the case of Xe which is the most documented, metals are synthesized above 150 GPa, i.e., at terrestrial core conditions, stoichiometric Xe-oxides between 50 and 100 GPa, i.e., in the P-T range of the Earth's lower mantle, but Xe-O high energy bonds may also form under the modest pressures of the Earth's crust (<1 GPa) in non-stoichiometric compounds. Most planetary relevant noble gas compounds found are with xenon, with only a few predicted helium compounds, the latter having no or very little charge transfer between helium and neighboring atoms.
American Mineralogist, 2020
Reactions involving carbon in the deep Earth have limited manifestations on Earth's surface, ... more Reactions involving carbon in the deep Earth have limited manifestations on Earth's surface, yet they have played a critical role in the evolution of our planet. The metal-silicate partitioning reaction promoted carbon capture during Earth's accretion and may have sequestered substantial carbon in Earth's core. The freezing reaction involving iron-carbon liquid could have contributed to the growth of Earth's inner core and the geodynamo. The redox melting/freezing reaction largely controls the movement of carbon in the modern mantle, and reactions between carbonates and silicates in the deep mantle also promote carbon mobility. The 10-year activity of the Deep Carbon Observatory has made important contributions to our knowledge of how these reactions are involved in the cycling of carbon throughout our planet, both past and present, and has helped to identify gaps in our understanding that motivate and give direction to future studies.
Chemical Geology, 2019
Abstract Equilibrium 37Cl/35Cl fractionation factors in selected molecules, Cl-bearing crystallin... more Abstract Equilibrium 37Cl/35Cl fractionation factors in selected molecules, Cl-bearing crystalline solids, and silicates in which Cl occurs at trace or minor concentration level are determined from first-principles calculations, within the density functional theory (DFT) scheme. Results on benchmarking molecules and crystalline solids are consistent with the previous theoretical study of Schauble et al. (2003) . The present study further documents the control of the isotopic fractionation properties of chlorine by its local bonding environment. Chloromagnesite and chlorapatite display similar isotopic fractionation properties due to relatively similar bonding environment. In contrast, trace Cl in Mg-serpentine (lizardite) and Mg-amphibole (anthophyllite) are enriched in 37Cl with respect to chloromagnesite, due to the structural constraints exerted by the host structure on the substituted ion. This effect is even more pronounced when Cl is associated to hydroxylated cationic vacancies in forsterite. An effect of the local bonding environment on the Cl isotopic fractionation properties is also inferred for Cl− ions in saturated aqueous solutions. It explains the systematic departure between theoretical and empirical reduced partition function ratio observed for the alkaline chlorides, differing from the agreement observed for the hydrated Cl salts. The reduced partition function ratio of Cl− ions in concentrated solution of alkaline chlorides is smaller from that observed in dilute solutions by an amount potentially reaching 1‰ at 22 °C. Finally, the calculation of fractionation factors between gas (HCl(g), NaCl(g), KCl(g)) and solids (sodalite, chlorapatite, halite, HCl trihydrate) which likely prevailed in the solar nebula, sustains a model in which the 37Cl enrichment of HCl(g) is produced by a Rayleigh type fractionation during chlorine condensation at temperatures between 400 and 500 K. This model could explain the heavier isotopic composition observed for bulk Earth and various chondrites compared to the nebular gas.
MRS Proceedings, 2006
The x-ray structure factor of water has been measured along the melting line to 57 GPa and 1500 K... more The x-ray structure factor of water has been measured along the melting line to 57 GPa and 1500 K using focused monochromatic synchrotron radiation and laser heated diamond anvil cell. The oxygen radial distribution function, g(r) is determined from these data. We have also calculated g(r) using ab initio methods and find a good agreement with the experiment. Based of the similarity of the measured and calculated structure factors determined density of water under extreme conditions unattainable previously.
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Papers by Chrystele Sanloup