Nathalie Bolfan

Nathalie Bolfan
Université Clermont Auvergne | Univ BPC · Laboratoire Magmas et Volcans

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124
Publications
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Publications

Publications (124)
Article
Full-text available
A significant portion of the Earth’s water is found at trace levels in nominally anhydrous rock forming minerals in the crust and mantle. Its distribution has far-reaching implications in melt-generating processes, mantle rheology and the stability of the lithosphere. We report petrographic, major and trace element, Fourier transform infrared spect...
Article
The internal or deep water cycle controls the volume of the oceans at the surface of the Earth. The advent of subduction 2–3 billion years ago initiated the transport of water back to the Earth's interior. With one ocean mass injected into the deep mantle over the last 2–3 billion years, some mantle regions must have become saturated and thus turne...
Article
Full-text available
Antigorite is considered as the most important source of water in subduction zones, playing a key role during arc magma genesis. Although, these magmas seem more oxidized than mid-oceanic ridge basalts (MORB), the possible inherent link between the oxidation state of arc magmas and serpentinite-derived hydrous fluids is still not well established....
Article
Full-text available
Open access: https://doi.org/10.1038/s41467-020-17442-8 Trace amounts of water dissolved in minerals affect density, viscosity and melting behaviour of the Earth’s mantle and play an important role in global tectonics, magmatism and volatile cycle. Water concentrations and the ratios of hydrogen isotopes in the mantle give insight into these proces...
Article
Full-text available
Olivine-hosted melt inclusions (MIs) provide samples of magmatic liquids and their dissolved volatiles from deep within the plumbing system. Inevitable post-entrapment modifications can lead to significant compositional changes in the glass and/or any contained bubbles. Re-heating is a common technique to reverse MI crystallisation; however, its ef...
Article
Iron speciation is linked to oxygen fugacity; hence the Fe³⁺/ΣFe ratio of glasses can reveal the oxygen fugacity of the system where they last equilibrated. Previous studies using X-ray Absorption Near Edge Structure (XANES) spectroscopy in silicate glasses and olivine-hosted melt inclusions have shown that arc basalts are more oxidized than mid-oc...
Article
The study of nominally anhydrous minerals with vibrational spectroscopy, despite its sensitivity, tends to produce large uncertainties (in absorbance or intensity) if the observed dispersion of the values arising from the anisotropy of interaction with light in non-cubic minerals is not assessed. In this study, we focused on Raman spectroscopy, whi...
Article
Full-text available
Plain Language Summary Mercury's weak magnetic field intensity that persisted over the last 3.9 billion years has long baffled the planetary science community. Various explanations have been proposed; nevertheless, there has been no consensus on how intrinsic dynamo with such weak energetics have existed in Mercury for prolonged period. In our subm...
Article
Full-text available
Phase relations for a natural serpentinite containing 5 wt% of magnetite have been investigated using a multi-anvil apparatus between 6.5 and 11 GPa and 400–850 °C. Post-antigorite hydrous phase assemblages comprise the dense hydrous magnesium silicates (DHMSs) phase A (11.3 wt% H2O) and the aluminous phase E (Al-PhE, 11.9 wt% H2O). In addition, a...
Conference Paper
Full-text available
Volatile abundances in magmas control the style, dynamics and intensity of volcanic eruptions. Reliable assessment of pre-eruptive conditions and degassing budget depends on correct estimation of the original volatile contents of magmas. Phenocryst-hosted melt inclusions (MI) record the volatile contents of the magma at the time of MI entrapment. D...
Poster
Island arc basalts (IAB) typically show a higher Fe3+/ΣFe ratio compared to that of ocean island basalts and mid-ocean ridge basalts [1-4]. It is argued that the sub-arc mantle is globally more oxidized than the depleted mantle [1-4]. Fe3+ enrichment in IABs was suggested to be caused by metasomatic agents expelled from the slab and percolati...
Article
Full-text available
Hydrous wadsleyite, ringwoodite, and phase D have been synthesized in the MgO-SiO2-H2O and MgO-FeO-SiO2-H2O systems at mantle transition zone conditions (15–21 GPa and 1,100–1,700°C) to investigate their water incorporation using Elastic Recoil Detection Analysis (ERDA), which is an absolute quantitative method. Wadsleyite and ringwoodite water con...
Article
New series of alumino-silicate glasses spanning a wide range of chemical compositions (basanites, tholeiitic basalts, calcalkaline andesites, peraluminous and peralkaline rhyolites) and with water contents from 0.02 to 6.70 wt% were used for improving the method of quantification of dissolved water with a highly confocal Raman micro-spectrometer. A...
Article
Full-text available
Hydrogen has been thought to be an important light element in Earth’s core due to possible siderophile behavior during core-mantle segregation. We reproduced planetary differentiation conditions using hydrogen contents of 450 to 1500 parts per million (ppm) in the silicate phase, pressures of 5 to 20 GPa, oxygen fugacity varying within IW-3.7 and I...
Article
Full-text available
The transition from the Archaean to the Proterozoic eon ended a period of great instability at the Earth’s surface. The origin of this transition could be a change in the dynamic regime of the Earth’s interior. Here we use laboratory experiments to investigate the solidus of samples representative of the Archaean upper mantle. Our two complementary...
Article
Full-text available
The low-velocity layer (LVL) atop the 410-km discontinuity has been widely attributed to dehydration melting. In this study, we experimentally reproduced the wadsleyite-to-olivine phase transformation in the upwelling mantle across the 410-km discontinuity and investigated in situ the sound wave velocity during partial melting of hydrous peridotite...
Article
We report concentrations of Chlorine (Cl) in synthetic wadsleyite (Wd) and ringwoodite (Rw) in the system NaCl–(Mg, Fe)2SiO4 under hydrous and anhydrous conditions. Multi-anvil press experiments were performed under pressures (14–22 GPa) and temperatures (1100–1400 °C) relevant to the transition zone (TZ: 410–670 km depth). Cl and H contents were m...
Article
The behavior of argon in H2O-CO2 bearing basaltic melts was experimentally investigated in the pressure range 1-5GPa and at temperatures between 1350 and 1600°C. Our experimental data simulate the partitioning of argon between an Ar-H2O-CO2 bearing fluid and a silicate melt occurring during magma ascent and degassing. The experimental results show...
Article
In the upper mantle, diamonds can potentially grow from various forms of media (solid, gas, fluid) with a range of compositions (e.g. graphite, C-O-H fluids, silicate or carbonate melts). Inclusions trapped in diamonds are one of the few diagnostic tools that can constrain diamond growth conditions in the Earth's mantle. In this study, inclusion-be...
Article
The kinetics of hydrogenation of dry iron-bearing olivine single crystals was determined by performing hydration experiments under hydrothermal conditions at high pressure. The experiments were performed in a multi-anvil press at 3 GPa, for a temperature range between 900 and 1200 °C and for various durations. The oxygen fugacity was buffered along...
Article
This study investigates the metal-silicate partitioning of Ni, Co, V, Cr, Mn and Fe during core mantle differentiation of terrestrial planets under hydrous conditions. For this, we equilibrated a molten hydrous CI chondrite model composition with various Fe-rich alloys in the system Fe-C-Ni-Co-Si-S in a multi-anvil over a range of P, T, and water c...
Article
Full-text available
Using large volume press, samples of bridgmanites (Bg) in equilibrium with both silicate melt and liquid Fe-alloy were synthesized to replicate the early period of core-mantle segregation and magma ocean crystallization. We observe that the Fe partition coefficient between Bg and silicate melt varies strongly with the degree of partial melting (F...
Data
Full-text available
Supplementary Tables for Boujibar et al. (2016, American Mineralogist 101(7):1560-1570) (Incorporation of Fe 2+ and Fe 3+ in bridgmanite during magma ocean crystallization)
Data
Full-text available
Supplementary Figures for Boujibar et al. (2016, American Mineralogist 101(7):1560-1570) (Incorporation of Fe 2+ and Fe 3+ in bridgmanite during magma ocean crystallization)
Article
Full-text available
Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (~1 S/m) that hasoften been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurementsof the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readilyexplain the g...
Article
It is now recognized that the transition zone (TZ) is a significant repository for water. This means that other volatile species may also be stored in this region such as halogen elements. We have measured the solubility of fluorine in wadsleyite (Wd) and ringwoodite (Rw) under hydrous and anhydrous conditions at different pressures and temperature...
Article
Full-text available
The plasticity of the dense hydrous magnesium silicate (DHMS) phase A, a key hydrous mineral within cold subduction zones, was investigated by two complementary approaches: high-pressure deformation experiments and computational methods. The deformation experiments were carried out at 11 GPa, 400 and 580 °C, with in-situ measurements of stress, str...
Article
Full-text available
The minerals constituting the Earth's upper mantle are nominally anhydrous silicates (NAMs). However they do contain hydrogen as a trace element, decorating point defects in their crystalline structure. Experimental petrology and mineralogy have quantified the maximum concentration under several compositional and thermodynamic conditions, but syste...
Article
Full-text available
Early in the Solar System’s history, energetic collisions of differentiated bodies affected the final composition of the terrestrial planets through partial destruction. Enstatite chondrites (EC) are the best candidates to represent the primordial terrestrial precursors as they present the most similar isotopic compositions to Earth. Here we report...
Data
Supplementary Figures 1-2, Supplementary Tables 1-2, Supplementary Notes 1-2 and Supplementary References
Article
Lawsonite is a calcium-aluminum bearing hydrous silicate mineral with CaAl2Si2O7(OH)2.H2O stoichiometry. It is thermodynamically stable in the hydrated oceanic crust. Low velocity anomalies observed in the cold subducted slabs have been related to the unusual shear wave velocities of lawsonite eclogite. However, electrical conductivity of lawsonite...
Article
We investigated the H2O content of olivine and garnet inclusions still trapped in seven uncut and unpolished kimberlitic diamonds from Udachnaya (Siberain craton). Fourier Transform Infrared (FTIR) spectroscopy analyses of the inclusions show spectra similar to those observed for the same minerals in mantle xenoliths. The olivine inclusions are fou...
Article
Full-text available
To test if hydrogen incorporation by ionic diffusion can occur between a volatile-rich kimberlitic liquid and forsterite, results of high-pressure and high-temperature experiments using a piston-cylinder apparatus at 1200-1300 °C and 1 GPa for durations of 1 min, 5 h, and 23 h, are reported here. Kimberlitic liquid in the system CaO-MgO-Al2O3-SiO2-...
Presentation
Full-text available
The oxydation state of Earth’s upper mantle (OSEUM) is a key thermodynamic parameter as it influences, among other variables, the depth of melting initiation, the liquidus/solidus temperatures and the composition of mantle melts, the speciation of numerous species (e.g., Fe, S, V…), the phase relations, the trace element partitionning, the volcanic...
Conference Paper
Full-text available
The solubility of Ar in H2O-CO2 bearing basaltic melts was experimentally determined in the pressure range 1-5 GPa and at temperatures between 1350 and 1600 °C. We used piston-cylinder apparatus (1-3 GPa) and multi-anvil apparatus (5 GPa). The argon concentrations in the quenched glasses were determined with electron microprobe, and the H2O and CO2...
Article
Full-text available
The Cerro del Almirez massif (Spain) represents a unique fragment of serpentinized oceanic lithosphere that has been first equilibrated in the antigorite stability field (Atg-serpentinites) and then dehydrated into chlorite-olivine-orthopyroxene (Chl-harzburgites) at eclogite facies conditions during subduction. The massif preserves a dehydration f...
Article
Full-text available
Serpentinites are an important component of the oceanic lithosphere that formed at slow to ultra-slow spreading centers. Serpentine could thus be one of the most abundant hydrous minerals recycled into the mantle in subduction zones. Prograde metamorphism in subducted serpentinites is characterized by the destabilization of lizardite into antigorit...
Article
Full-text available
The geological materials in Earth's lowermost mantle control the characteristics and interpretation of seismic ultra–low velocity zones at the base of the core-mantle boundary. Partial melting of the bulk lower mantle is often advocated as the cause, but this does not explain the nonubiquitous character of these regional seismic features. We explor...
Article
Full-text available
The geological materials in Earth's lowermost mantle control the characteristics and interpretation of seismic ultra–low velocity zones at the base of the core-mantle boundary. Partial melting of the bulk lower mantle is often advocated as the cause, but this does not explain the nonubiquitous character of these regional seismic features. We explor...
Article
Full-text available
Partitioning of sulphur between liquid Fe-rich metals and silicates ( ) was investigated at temperatures from 1800 °C to 2400 °C, pressures from 2 to 23 GPa and oxygen fugacities from 3.5 to 1.5 log units below the iron-wüstite buffer, using multi-anvil apparatus. The results are combined with previous experimental works to refine a multi-variable...
Data
Excel file calculating sulfur partition coefficient between metal and silicate based on Eq. 11 in Boujibar et al. (2014, 391:42-54)
Article
Full-text available
Compressibility of perovskite-structured Ca3Al2Si3O12 grossular (GrPv) was investigated at high pressure and high temperature by means of angle-dispersive powder X-ray diffraction using a laser-heated diamond anvil cell. We observed the Pbnm orthorhombic distortion for the pure phase above 50 GPa, whereas below this pressure, Al-bearing CaSiO3 pero...
Article
Full-text available
Crystals of ferrous and ferric iron-bearing hydrous wadsleyite have been synthesized at 1400 ºC and 12–13.5 GPa in a multi-anvil press. Crystal structures (atom positions, occupancies, and cell parameters) have been refined by single-crystal X-ray diffraction at ambient conditions. Assuming cation vacancies to be in the M3 site only, their concentr...
Article
We have measured the water contents in forsterites and olivines synthesized in the multi-anvil press using confocal Raman spectroscopy. These samples were previously characterized for water contents by polarized FTIR and contain from 75 to 1300 ppm wt H2O. We find that both forsterite and olivine follow the same trend in water content vs. integrate...
Article
This study investigates the metal–silicate partitioning of Pb and U (DPb and DU, respectively) during core-mantle differentiation of terrestrial planets. For this, we equilibrated a molten CI-chondrite model mantle-composition with various Fe-rich alloys in the system Fe–C–Ni–Si–S in a multi-anvil over a range of P, T, fO2 (3–8 GPa, 2073–2373 K and...
Article
The mechanism and kinetics of the α-β transformation in San Carlos olivine α-Mg1.8Fe0.2SiO4 containing ca. 526 wt.ppm H2O were studied in situ by time-resolved synchrotron X-ray diffraction (XRD) in the range 12.5 - 14.5 GPa and 870 - 1150 K. Time series of XRD spectra reveal the early formation of an intermediate phase that further transforms to w...
Article
Experiments were performed under water-saturated conditions in the MFSH (MgO–FeO–SiO2–H2O) and MFASH (MgO–FeO–Al2O3–SiO2–H2O) systems at 2.5, 5, 7.5 and 9 GPa, at temperatures from 1175 to 1400 °C and H2O initial abundance of 0.5–5 wt%. One experiment was performed at 13.5 GPa at a temperature of 1400 °C in the MFSH system. Water contents were anal...
Article
Full-text available
Wadsleyites with various iron contents were synthesized at ~12–14 GPa and 1400 °C under oxidizing and hydrous conditions in coexistence with enstatite. The samples were studied using micro-X-ray absorption near edge structure (XANES) and micro-Mössbauer spectroscopy to determine the ferric iron contents in polyphasic samples and secondary ion mass...
Article
We investigated the melting properties of a synthetic chondritic primitive mantle up to core-mantle boundary (CMB) pressures, using laser-heated diamond anvil cell. Melting criteria are essentially based on the use of X-rays provided by synchrotron radiation. We report a solidus melting curve lower than previously determined using optical methods....
Article
Trace amounts of hydrogen dissolved as defects in nominally anhydrous minerals (NAMs) in the mantle are believed to play a key role in physical and chemical processes in the Earth's upper mantle. Hence, the estimation of water storage in mantle phases and solubility mechanisms are important in order to better understand the effect of water. Experim...
Presentation
The 410 km-discontinuity is often invoked to bare a great deal of information about the chemical and thermal state of the Earth's mantle. Indeed the olivine to wadsleyite transformation is sensitive to many parameters such as temperature, iron content, water content and oxygen fugacity. However, it is yet difficult to state on what is the chemistry...