Marion Louvel

Institut des Sciences de la Terre d'Orleans

Rare earth elements (REE), essential metals for the transition to a zero-emission economy, are mostly extracted from REE-fluorcarbonate minerals in deposits associated with carbonatitic and/or peralkaline magmatism. While the role of high-temperature fluids (100 < T < 500 °C) in the development of economic concentrations of REE is well-established,...

Chlorine is the most common ligand in geofluids, and one of the most important complexing agents for rare earth elements. The geometry and thermodynamic properties of La(III)-Cl complexes determined by previous experimental studies show inconsistency especially at temperature over 350 C. Here, ab initio molecular dynamics (MD) simulations were empl...

Rare Earth elements (REE) are gaining importance due to their increasing industrial applications and usefulness as petrogenetic indicators. REE-sulfate complexes are some of the most stable REE aqueous species in hydrothermal fluids, and may be responsible for REE transport and deposition in a wide variety of geological environments, ranging from s...

Earth's deep carbon cycle affects atmospheric CO 2 , climate, and habitability. Owing to the extreme solubility of CaCO 3 , aqueous fluids released from the subducting slab could extract all carbon from the slab. However, recycling efficiency is estimated at only around 40%. Data from carbonate inclusions, petrology, and Mg isotope systematics indi...

We present a new autoclave that enables in situ characterization of hydrothermal fluids at high pressures and high temperatures at synchrotron x-ray radiation sources. The autoclave has been specifically designed to enable x-ray absorption spectroscopy in fluids with applications to mineral solubility and element speciation analysis in hydrothermal...

Modelling the reservoirs and fluxes of Zn in Earth's crust and mantle requires data on the solubility of its mineral hosts and ores in coexisting fluids, as well as on the complexation of Zn in these fluids as a function of fluid composition, pressure, and temperature. However, due to experimental challenges, the availability of such data is limite...

We present a new analytical method, which allows the simultaneous analysis of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) in geological samples. To account for interferences of Fe on the spectral lines of F, of Al on Br-lines, and of Ca on I-lines, we prepared four new halogen-free calibration glasses. The new method is used to analyz...

Understanding the behavior of halogens (Cl, Br, and I) in subduction zones is critical to constrain the geochemical cycle of these volatiles and associated trace metals, as well as to quantify the halogen fluxes to the atmosphere via volcanic degassing. Here, the partitioning of bromine between coexisting aqueous fluids and hydrous granitic melts a...

The volcanic degassing of halogens, and especially of the heavier Br and I, received increased attention over the last 20 years due to their significant effect on atmospheric chemistry, notably the depletion of stratospheric ozone. While the effect of melt composition on halogen diffusion, solubility, or fluid-melt partitioning in crustal magma cha...

Accurate knowledge of rare earth elements (REE) speciation in high pressure – high temperature fluids is required to model REE transport and precipitation in subduction zones and magmatic-hydrothermal environments, and the formation of rare metal deposits. Recent experiments (lanthanum, ytterbium, erbium) have demonstrated that REE chloride complex...

A new diamond-anvil cell apparatus for in situ synchrotron X-ray diffraction measurements of liquids and glasses, at pressures from ambient to 5 GPa and temperatures from ambient to 1300 K, is reported. This portable setup enables in situ monitoring of the melting of complex compounds and the determination of the structure and properties of melts u...

Abstract. Understanding the behavior of halogens (Cl, Br, and I) in subduction zones is critical to constrain the recycling of trace elements and metals, and to quantify the halogen fluxes to the atmosphere via volcanic degassing. Here, the partitioning of bromine between coexisting aqueous fluids and hydrous granitic melts and its speciation in sl...

We report a new diamond anvil cell apparatus for in situ synchrotron X-ray diffraction and absorption measurements of liquids and glasses at pressures from ambient to 5 GPa and temperatures from ambient to 1300 K. This portable set-up enables in situ monitoring of melting of complex compounds, and the determination of the structure and properties o...

Here we report the results of multiple analytical techniques on sub-mm particulate material derived from Unit 1 of the Fukushima Daiichi Nuclear Power Plant to provide a better understanding of the events that occurred and the environmental legacy. Through combined x-ray fluorescence and absorption contrast micro-focused x-ray tomography, entrapped...

Volatiles fluxes in subduction zones play a critical role in the Earth’s chemical evolution, contributing not only to the hydrous melting of the mantle wedge and development of arc volcanism, but also to the composition of our atmosphere. While halogens are minor volatiles compare to H2O and CO2, their ability to complex with other elements makes t...

The effect of S on the solubility of Cu in high-temperature fluids at conditions relative to porphyry and epithermal ore deposit formation has been investigated conducting in situ X-ray absorption (XAS) and Raman spectroscopy from 325 to 600 °C at 300 bars. The experimental results identify the Cl or S-complexes responsible for Cu transport in high...

Vibrational spectroscopy is a fundamental tool to investigate local atomic arrangements and the effect of the environment, provided that the spectral features can be correctly assigned. This can be challenging in experiments and simulations when double peaks are present because they can have different origins. Fermi dyads are a common class of such...

The increasing demand for Rare Earth elements (La to Yb, +Sc and Y) from the green and communication industries calls for a better understanding of the processes leading to their concentration in the Earth’s crust and especially those that may favor enrichment in the most valuable LREEs (Nd, Pr and Eu) or HREEs (Tb, Dy and Y) in different environme...

Volatiles released to the mantle-wedge by slab-derived fluids (aqueous fluids, hydrous melts or solute-rich supercritical liquids) are expected to have a significant impact on the chemistry of the mantle wedge, and have been suggested to favor the development of oxidative conditions in the sub-arc mantle [1]. The actual composition of such fluids r...

Despite the continuously growing demand for rare metals, the role of high temperature fluids in the formation of HFSE and REE economic enrichments in magmatic-hydrothermal systems (e.g., Bayan Obo, China; Thor Lake, Canada; Brockman/Hastings, Australia) remains poorly understood. For instance, current knowledge of those fluids' composition and the...

High pressure-high temperature experiments are used to investigate the effect of temperature, pH and fluid composition on the transport and deposition of REE and provide constraints on the role of hydrothermal fluids in the formation of rare metal deposits. In situ X-ray absorption (XAS) measurements were conducted at 50 MPa to determine simultaneo...

The effect of temperature, composition and pH on the solubility and speciation of REE in high temperature fluids has been determined by in situ X-ray absorption measurements (XAS) up to 600 °C and 100 MPa to investigate the potential role of hydrothermal fluids in the transport, segregation and deposition of REE in carbonatitic and peralkaline igne...

A high-pressure/high-temperature cell dedicated to Raman spectroscopy is presented. The P and T ranges are op-timized for the study of supercritical fluids (T ≤ 975 K, P ≤ 200 MPa); the P and T parameters are controlled in-dependently. The autoclave was adapted from a previous cell (designed for X-ray absorption and scattering spectroscopies) to an...

abstraCt The partitioning of Zr between high P-T aqueous fluids and melts has been investigated in situ in the haplogranite-H 2 O and haplogranite-(F)-H 2 O systems to assess the mobilization of high field strength elements (HFSE) in magmatic-hydrothermal processes in subduction zones. The partition coefficients D f/ Z m r were determined from Zr c...

Aqueous fluids and vapors that exsolve from silicate melt as magma rises through the upper crust are of critical importance in volcanic arcs. They can for instance affect the dynamics of magma ascent and trigger eruption or favor the mobilization of metals as Cu, Au and Mo at the origin of the formation of porphyry ore deposits [1, 2]. Up to now, c...

Field observations and solubility experiments show evidence for the efficient mobilization of nominally insoluble HFSE (i.e., Ti, Zr, Nb and Hf) by high pressure fluids, probably via complexation with polymerized alkali-silica dissolved species and halogens (F and Cl). Here we investigate the complexation of Zr in subduction-related fluids (aqueous...

Accelerated ageing of dental TZP were investigated at 134 degrees C for 2 h under 2.3 bar water vapor pressure. The TZP blanks were sintered in the range from 1350 to 1580 degrees C. The average grain size of 1350 and 1400 degrees C sintered materials were <0.3 mu m whereas higher sintering temperatures led to larger grain sizes. The grain size and...

A combined magneto-mineralogical approach is used to diagnose maghemitization in magnetic grains of basaltic rock fragments from sand dunes in the Namibian desert in SW Africa. Data were obtained from static magnetic analysis, ferromagnetic resonance (FMR) spectroscopy, micro-Raman spectroscopy and electron microscopy. Micro-Raman spectroscopy show...

Although halogens are minor volatiles in the Earth's crust, they are important tracers of magmatic and degassing processes and provide insights about subsurface magma movement and eruption likelihood in subduction-related volcanism [1]. Additionally, their ability to complex with other elements has also considerable implications on the formation an...