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223 results on '"Bruno Scaillet"'

1. On the Budget and Atmospheric Fate of Sulfur Emissions From Large Volcanic Eruptions

Author

Bruno Scaillet and Clive Oppenheimer

Subjects
sulfur, volcanoes, atmosphere, climate, eruption, petrology, Geophysics. Cosmic physics, QC801-809
Abstract

Abstract Today, volcanic sulfur emissions into the atmosphere are measured spectroscopically from the ground, air and space. For eruptions prior to the satellite era, two main sulfur proxies are used, the rock and ice core records, as illustrated by Peccia et al. (2023, https://doi.org/10.1029/2023gl103334). The first approach is based on calculations of the sulfur content of the magma, while the second uses traces of sulfur deposited in ice. Both approaches have their limitations. For glaciochemistry, the volcano responsible for a sulfur anomaly is often unknown and the atmospheric pathway by which the sulfur reached the ice uncertain. The petrologic method relies, too, on uncertain estimates of eruption size and a number of geochemical assumptions that are hard to verify. A deeper knowledge of processes occurring both within magma bodies prior to eruption, and within volcanic plumes in the atmosphere is needed to further our understanding of the impacts of volcanism on climate.

Published
2024
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2. CO2‐Undersaturated Melt Inclusions From the South West Indian Ridge Record Surprisingly Uniform Redox Conditions

Author

Yves Moussallam, Guillaume Georgeais, Estelle F. Rose‐Koga, Kenneth T. Koga, Margaret E. Hartley, Bruno Scaillet, Clive Oppenheimer, and Nial Peters

Subjects
oxygen fugacity, undersaturated melts, XANES, melt inclusions, mid‐ocean ridge basalts, Geophysics. Cosmic physics, QC801-809, Geology, QE1-996.5
Abstract

Abstract The behavior of Fe3+ during mantle partial melting strongly influences the oxidation state of the resulting magmas, with implications for the evolution of the atmosphere's oxidation state. Here, we challenge a prevailing view that low‐degree partial melts are more oxidized due to the incompatible behavior of Fe3+. Our study is based on measurements of Fe3+/∑Fe along with major, minor, trace and volatile elements in olivine‐ and plagioclase‐hosted melt inclusions of CO2 undersaturated mantle melts in South West Indian Ridge lava. These inclusions record minimum entrapment pressures equivalent to depths up to 10 km below the seafloor, record magma ascent rates of 0.03–0.19 m/s, and display exceptionally high CO2/Ba, CO2/Rb, and CO2/Nb ratios, indicative of a CO2‐rich mantle source. Accounting for fractional crystallization, we find a uniform melt oxidation state (with an Fe3+/ΣFe at 0.140 ± 0.005 at MgO = 10 wt.%) that displays no systematic variation with major, minor, volatile or trace element contents, thus providing no evidence for a relationship between the degree of partial melting and Fe3+/ΣFe. This can be explained by efficient buffering of Fe3+/∑Fe and fO2 of mid‐ocean ridge basalt melts by their surrounding mantle and/or a decrease in the bulk peridotite‐melt Fe2O3 partition coefficient with increasing partial melting. We conclude that changes in the Earth's upper mantle temperature over geological time need not have affected the oxidation state of volcanic products or of the atmosphere.

Published
2023
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3. Modest volcanic SO2 emissions from the Indonesian archipelago

Author

Philipson Bani, Clive Oppenheimer, Vitchko Tsanev, Bruno Scaillet, Sofyan Primulyana, Ugan Boyson Saing, Hilma Alfianti, and Mita Marlia

Subjects
Science
Abstract

Indonesia is the country with the most active volcanoes, several of which are renowned for climate-changing eruptions. Here the authors show a rather moderate sulfur emissions budget and reinforce the idea that sulfur-rich eruptions reflect long-term accumulation of volatiles in the reservoirs.

Published
2022
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4. Pre-eruptive excess volatiles and their relationship to effusive and explosive eruption styles in semi-plugged volcanoes

Author

Sri Budhi Utami, Juan Andùjar, Fidel Costa, Bruno Scaillet, Hanik Humaida, and Simon Carn

Subjects
experimental petrology, Kelud, Kelut, eruption style, volatiles, volcano monitoring, Science
Abstract

Understanding the role of various factors influencing eruption style is challenging, but it can aid in adapting different hazard mitigations and crisis responses for explosive or effusive events. Here, we focus on the role of magma storage conditions in controlling eruption styles at basaltic andesite volcanoes, and how they can be related to monitoring data. We study the cycle of explosive (1990, sub-Plinian) → effusive (2007, dome) → explosive (2014, sub-Plinian) eruptions from Kelud (Kelut) volcano, Indonesia. We conducted petrological analyses of the eruption products and phase equilibria experiments using pumice and explored a range of temperatures, pressures, oxygen fugacity, and volatile contents. We show that we can reproduce the main mineral assemblage (plagioclase ± pyroxenes ± magnetite ± amphibole ± olivine) and phenocryst content (30–50 wt%) of the magmas from the three eruptions at T = 975 ± 39°C, p = 175 ± 25 MPa, fO2 = nickel–nickel oxide buffer, and about 4–6 wt% water in the melt (ca. 3 to 5 wt% and ca. 4 to 7 wt% for the 1990 and 2014 eruptions, respectively). However, geothermobarometric results also indicate that some crystals of amphibole were sourced from higher pressures. We infer from a synthesis of our data and historical observations that the high phenocryst content of the 2007 dome (∼70 wt%) likely resulted from slow magma ascent toward the surface alongside progressive degassing and re-equilibration at a lower volatile content (∼1 wt% water in the melt). Mass balance calculations on the sulfur budget of the 1990, 2007, and 2014 magmas show that the explosive events contained an excess fluid phase at pre-eruptive conditions, and we propose that this led to their higher explosivity compared to the 2007 dome. The accumulation of excess fluids during decadal-long repose depends on how plugged the volcanic system is, or its ability to passively release magmatic fluids, prior to eruption. Such condition could be inferred from monitoring records, including changes in gravity of the plumbing system over time, and thus contribute to better anticipate eruptive style.

Published
2022
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5. Crystallization Kinetics of Alkali Feldspar in Peralkaline Rhyolitic Melts: Implications for Pantelleria Volcano

Author

Fabio Arzilli, Paola Stabile, Alessandro Fabbrizio, Patrizia Landi, Bruno Scaillet, Eleonora Paris, and Michael R. Carroll

Subjects
alkali feldspar, peralkaline rhyolite, nucleation delay, crystallization kinetics, Pantelleria volcanic system, Science
Abstract

Peralkaline rhyolites, associated with extensional tectonic settings, are medium to low viscosity magmas that often produce eruptive styles ranging from effusive to highly explosive eruptions. The role of pre-eruptive conditions and crystallization kinetics in influencing the eruptive style of peralkaline rhyolitic magmas has been investigated and debated considering equilibrium conditions. However, experimental constraints on the effect of disequilibrium in crystallization in such magmas are currently lacking in the literature. Therefore, we performed isobaric cooling experiments to investigate alkali feldspar crystallization kinetics in peralkaline rhyolitic melts. Experiments were performed under water-saturated, water-undersaturated, and anhydrous conditions between 25 and 100 MPa, at 670–790°C and with experimental durations ranging from 0.5 to 420 h. Here we present the first data on crystallization kinetics of alkali feldspar, which is the main crystal phase in peralkaline rhyolitic melts, in order to improve our understanding of the evolutionary timescales of these melts and their ability to shift between effusive and explosive activity. Our experimental results indicate that the alkali feldspar nucleation delay can range from hours to several days as a function of undercooling and H2O content in the melt. Thus, a peralkaline rhyolitic magma can be stored at the pre-eruptive conditions for days without important variations of its crystal fraction. This suggests that crystallization may not necessarily play the main role in triggering fragmentation during explosive eruptions of peralkaline rhyolitic magmas.

Published
2020
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6. Melting conditions in the modern Tibetan crust since the Miocene

Author

Jinyu Chen, Fabrice Gaillard, Arnaud Villaros, Xiaosong Yang, Mickael Laumonier, Laurent Jolivet, Martyn Unsworth, Leïla Hashim, Bruno Scaillet, and Guillaume Richard

Subjects
Science
Abstract

Crustal melting may play a fundamental role in orogenic processes, but quantifying crustal melt remains difficult. Here, the authors combine pressure-temperature paths, electrical conductivity and geophysical data to elucidate the melting conditions in Tibet since the Miocene.

Published
2018
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7. Publisher Correction: Melting conditions in the modern Tibetan crust since the Miocene

Author

Jinyu Chen, Fabrice Gaillard, Arnaud Villaros, Xiaosong Yang, Mickael Laumonier, Laurent Jolivet, Martyn Unsworth, Leїla Hashim, Bruno Scaillet, and Guillaume Richard

Subjects
Science
Abstract

The original PDF version of this Article contained an error in which Fig. 3 and its legend were omitted and Equations 5 and 6 contained errors.This has been corrected in the PDF version of the Article. The HTML version was correct from the time of publication.

Published
2018
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12. A novel approach to volcano surveillance using gas geochemistry

Author

Yves Moussallam, Clive Oppenheimer, and Bruno Scaillet

Subjects
General Earth and Planetary Sciences, General Environmental Science
Abstract

Identifying precursory phenomena is central to the short-range assessment and anticipation of volcanic hazards. The chemistry of gases, which may separate from magma at depth, is operationally monitored at many volcanoes worldwide to manage risk. However, owing to the complexity of volcanic degassing, decoding the message of gas geochemistry has proven challenging. Here, we report an approach to restoration of measured volcanic gas compositions that enables tracking of variations in the temperature and/or oxidation state of the source magma. We validate the approach with reference to independent estimates of melt oxidation state obtained by X-ray absorption near-edge structure (XANES) spectroscopy at the iron K-edge. We then apply the method to a global database of high temperature volcanic gases and to extended gas geochemical timeseries at Unzen, Aso, and Asama volcanoes, identifying hitherto unreported but significant changes in magma intensive parameters that preceded or accompanied changes in volcanic activity. Restoration of volcanic gas compositions offers a promising complement to monitoring strategies at active volcanoes, calling for more systematic operational surveillance of redox-sensitive gas species., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

16. Redox Controls during Magma Ocean Degassing

Author

Fabien Bernadou, Mathieu Roskosz, Yves Marrocchi, Giada Iacono-Marziano, Mohamed Ali Bouhifd, Bruno Scaillet, Manuel A. Moreira, Grégory Rogerie, Fabrice Gaillard, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), ANR-18-CE31-0021,GASTON,Les constituants volatils dans les processus magmatiques du noyau aux atmosphères(2018), and ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010)

Subjects
010504 meteorology & atmospheric sciences, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Astrobiology, Atmosphere, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, Geochemistry and Petrology, Lithosphere, Earth and Planetary Sciences (miscellaneous), Volatiles, 0105 earth and related environmental sciences, Crust, magma ocean, Outgassing, Geophysics, volatiles, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], redox, Magma, atmosphere, Terrestrial planet, Geology, mantle
Abstract

International audience; Nitrogen, carbon, hydrogen and sulfur are essential elements for life and comprise about 1 % of terrestrial planet masses. These elements dominate planetary surfaces due to their volatile nature, but the Earth's interior also constitutes a major C-H-N-S reservoir. Resolving the origin of the surficial versus deep volatile reservoirs requires the past 4.5 Giga-years of mantle outgassing and ingassing processes to be reconstructed, involving many unknowns. As an alternative, we propose to define the primordial distribution of volatiles resulting from degassing of the Earth's magma ocean (MO). The equilibrium partitioning of C-H-ON -S elements between the MO and its atmosphere is calculated by means of solubility laws, extrapolated to high temperatures and over a large range of redox conditions. Depending on the redox conditions, the amount of volatiles, and the size of the MO considered, we show that the last MO episode may have degassed 40-220 bar atmospheres, whereas hundreds to thousands of ppm of C-H-ON -S can be retained in the magma. Two contrasting scenarios are investigated: reduced vs. oxidized MO. For reduced cases (IW+2) would be dry and C-N-S-rich. An intermediate redox state produces a C-N atmosphere. In many cases, the present-day surficial abundances (atmosphere+ocean+crust) of C and N, the most volatile elements, are very close to the calculated primordial MO-atmosphere distribution. This probably means that lithospheric recycling and post-magma ocean degassing only moderately alter the surficial abundances of these elements. Sulfur, in contrast, must have been mostly outgassed by post-MO events. Changes in redox conditions during magma ocean degassing played a first order role in the composition of the primordial atmosphere of planets. We suggest that the more oxidized conditions on Venus due to H-loss may have played a role in the growth of a dry MO atmosphere on this planet compared to an H-bearing one on Earth. To verify these first order assertions, constraints on volatile behaviour under extreme magma ocean conditions and upon magma ocean solidification are urgently needed.

Published
2022

19. The Role of Magma Storage Conditions and Excess Fluids in the Effusive to Explosive Eruption Styles

Author

Fidel Costa, Hanik Humaida, Bruno Scaillet, Sri Budhi Utami, and Joan Andújar

Subjects
geography, Basaltic andesite, geography.geographical_feature_category, Explosive eruption, Explosive material, Volcano, Monitoring data, Magma, Excess fluids, Petrology, Geology
Abstract

We investigate the role of pre-eruptive magma conditions in controlling eruption styles at basaltic andesite volcanoes, and their relationship to monitoring data. We focus on a cycle of explosive (...

Published
2021

20. Modest volcanic SO

Author

Philipson, Bani, Clive, Oppenheimer, Vitchko, Tsanev, Bruno, Scaillet, Sofyan, Primulyana, Ugan Boyson, Saing, Hilma, Alfianti, and Mita, Marlia

Abstract

Indonesia hosts the largest number of active volcanoes, several of which are renowned for climate-changing historical eruptions. This pedigree might suggest a substantial fraction of global volcanic sulfur emissions from Indonesia and are intrinsically driven by sulfur-rich magmas. However, a paucity of observations has hampered evaluation of these points-many volcanoes have hitherto not been subject to emissions measurements. Here we report new gas measurements from Indonesian volcanoes. The combined SO

Published
2021

21. Experimental characterization of heavy halogens behavior in alkaline magmas

Author

Joan Andújar, Carmela Faranda, Gaëlle Prouteau, Bruno Scaillet, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC)

Subjects
13. Climate action, Chemistry, [SDU]Sciences of the Universe [physics], Inorganic chemistry, Halogen, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Characterization (materials science)
Abstract

International audience; Halogens are minor volatile species emitted during volcaniceruptions, whose injection into the atmosphere contributes to thediminution of the stratospheric ozone layer and causes majorclimatic impacts. However, the lack of detailed understandingconcerning halogens behavior in magmas – especially bromineand iodine - and their degassing during magma ascent, prevents afull assessment of halogen cycling in the Earth’s system.Previous studies on iron-free synthetic systems have shown thatthe partitioning of Cl, Br and I between fluids and silicate meltsincreasingly favors the former as the ionic radii of the halogenideions increases [1]. These results suggest that bromine and iodinefluxes to the atmosphere are probably underestimated. Toevaluate this phenomenon, additional experimental constraints onBr and I behavior in natural magmas are urgently needed. In thisstudy, the Br partitioning between fluids and natural silicatemelts has been investigated experimentally as a function of meltcomposition, pressure, temperature and oxygen fugacity.Composition investigated and corresponding geodynamicsettings are representative of alkaline/hyperalkaline magmaticsystems worldwide. Experiments were performed in internallyheated pressure vessels (IHPV) under controlled oxygen fugacityand allowing drop quench. Bromine abundances weredetermined by μ-XRF, LA-ICP-MS or nanoSIMS, while fluidcomposition was estimated by mass balance calculations. Ourresults confirm the preference of bromine for the fluid phase,whatever the experimental conditions investigated, being inagreement with previous studies on metaluminous compositions[2], DBrf/m increasing with melt silica content. Due to its very lowconcentration in magmas, iodine behavior remains particularlypoorly known. To address this issue, we have carried out HP-HTsolubility experiments to synthesize a series of reference glasses,in order to test several sensitive analytical techniques for iodinequantification, such as LA-ICP-MS, nanoSIMS or neutronirradiation noble gas mass spectrometric technique. Dataacquired in this study will enrich a still fragmentary knowledgeof deep halogens geochemistry and therefore constitute part ofthe essential basis to develop the first physically-basedquantitative framework for volcanic heavy halogen emissions.[1] Bureau et al., (2000), Earth And Planetary Science Letters183, 51-60.[2] Cadoux et al., (2018), Earth And Planetary Science Letters498, 450–463.

Published
2021

22. The Role of Sulphur on the Melting of Ca-Poor Sediment and on Trace Element Transfer in Subduction Zones: An Experimental Investigation

Author

Bruno Scaillet, Anne-Aziliz Pelleter, Gaëlle Prouteau, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), CNRS-INSU - TellusS - SYSTER, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), and ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011)

Subjects
010504 meteorology & atmospheric sciences, Mantle wedge, Partial melting, Trace element, Analytical chemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Silicate, Phengite, chemistry.chemical_compound, Geophysics, chemistry, [SDU]Sciences of the Universe [physics], 13. Climate action, Geochemistry and Petrology, Phase (matter), Pelite, engineering, Biotite, Geology, 0105 earth and related environmental sciences
Abstract

We performed phase equilibrium experiments on a natural Ca-poor pelite at 3 GPa, 750–1000°C, under moderately oxidizing conditions, simulating the partial melting of such lithologies in subduction zones. Experiments investigated the effect of sulphur addition on phase equilibria and compositions, with S contents of up to ∼ 2.2 wt. %. Run products were characterized for their major and trace element contents, in order to shed light on the role of sulphur on the trace element patterns of melts produced by partial melting of oceanic Ca-poor sediments. Results show that sulphur addition leads to the replacement of phengite by biotite along with the progressive consumption of garnet, which is replaced by an orthopyroxene-kyanite assemblage at the highest sulphur content investigated. All Fe-Mg silicate phases produced with sulphur, including melt, have higher MgO/(MgO+FeO) ratios (relative to S-free/poor conditions), owing to Fe being primarily locked up by sulphide in the investigated redox range. Secular infiltration of the mantle wedge by such MgO and K2O-rich melts may have contributed to the Mg and K-rich character of the modern continental crust. Addition of sulphur does not affect significantly the stability of the main accessory phases controlling the behaviour of trace elements (monazite, rutile and zircon), although our results suggest that monazite solubility is sensitive to S content at the conditions investigated. The low temperature (∼ 800 °C) S-bearing and Ca-poor sediment sourced slab melts show Th and La abundances, Th/La systematics and HFSE signatures in agreement with the characteristics of sediment-rich arc magmas. Because high S contents diminish phengite and garnet stabilities, S-rich and Ca-poor sediment sourced slab melts have higher contents of Rb, B, Li (to a lesser extent), and HREE. The highest ratios of La/Yb are observed in sulphur-poor runs (with a high proportion of garnet, which retains HREE) and beyond the monazite out curve (which retains LREE). Sulphides appear to be relatively Pb-poor and impart high Pb/Ce ratio to coexisting melts, even at high S content. Overall, our results show that Phanerozoic arc magmas from high sediment flux margins owe their geochemical signature to the subduction of terrigenous, sometimes S-rich, sediments. In contrast, subduction of such lithologies during Archean appears unlikely or unrecorded.

Published
2021

23. Spectral Emissivity of Phonolite Lava at High Temperature

Author

Clive Oppenheimer, Aneta Slodczyk, Patrick Echegut, Hao Li, Jonas Biren, Bruno Scaillet, Joan Andújar, Domingos De Sousa Meneses, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université d'Orléans (UO), University of Cambridge [UK] (CAM), TelluS program of CNRS/INSU with RADIABAR project, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), and ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011)

Subjects
Infrared, Lava, Mineralogy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 02 engineering and technology, 01 natural sciences, Temperature measurement, Spectral line, remote sensing, 0103 physical sciences, Emissivity, Radiative transfer, Electrical and Electronic Engineering, 010302 applied physics, biology, Erebus, 021001 nanoscience & nanotechnology, biology.organism_classification, 13. Climate action, radiative transfer, [SDU]Sciences of the Universe [physics], Radiance, phonolite lava, General Earth and Planetary Sciences, thermal infrared, 0210 nano-technology, Geology, temperature measurement
Abstract

International audience; The rheology and thermodynamical evolution of magma, either in reservoirs, conduits or at the surface, are governed by temperature. To determine the field temperature, remote sensing methods based on measuring the infrared radiance are widely applied, but they are subject to assumptions and caveats that can propagate into large uncertainties. This is related to the poor knowledge of one of the most critical parameters, namely the spectral emissivity. In this work we aim at filling this gap through in situ spectral emissivity measurements performed over wide temperature (700-1600 K) and spectral ranges (1.25-25 µm) on two representative phonolitic compositions from Erebus (Antartica) and Teide (Spain) volcanoes. The laboratory spectra allow to determine precisely spectral emissivity in the thermal infrared (TIR), middle infrared (MIR), and shortwave infrared (SWIR) ranges. The results reveal the complexity and contrasted behavior of the radiative properties of the two rocks melts, despite their broadly similar composition. The spectral emissivity varies significantly as a function of temperature, composition, crystallinity, thickness, and thermal history. Altogether, the data reveal that emissivity cannot be considered as a constant value and question previous arguments that active lava always has lower emissivity than frozen lava. Finally, the laboratory-measured values of spectral emissivity were used to refine the temperature of Erebus lava lake gathered from previous remote sensing methods.

Published
2021

24. Experimental constraints on pre-eruption conditions of the 1631 Vesuvius eruption

Author

Raffaello Cioni, Ilaria Bardeglinu, Bruno Scaillet, Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), and ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011)

Subjects
Vesuvius, experimental petrology, 1631 eruption, alkaline magmas, Felsic, 010504 meteorology & atmospheric sciences, Geochemistry, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Geophysics, 13. Climate action, Geochemistry and Petrology, Mineral redox buffer, [SDU]Sciences of the Universe [physics], engineering, Plagioclase, Saturation (chemistry), Tephra, Leucite, Geology, Amphibole, Biotite, 0105 earth and related environmental sciences
Abstract

International audience; We established the phase equilibria of a representative tephriphonolitic sample of the 1631 eruption of Vesuvius (Italy). Experiments were conducted at 100 MPa, in the temperature range 950–1050 °C for melt water content ranging from 1.3 to 3.2 wt%, and at an oxygen fugacity (fO2) of NNO+1 to NNO+3 (one to three log unit above the fO2 of the Ni-NiO solid redox buffer). Results show that clinopyroxene, biotite and leucite dominate the crystallizing phase assemblage, with minor proportions of plagioclase and amphibole, in agreement with the petrological attributes of the tephra. Comparison between the phase proportions and compositions obtained in experiments and those observed in the rock indicates a pre-eruptive temperature of 950 ± 30° and a melt water content H2Omelt = 2.3 ± 0.3 wt%, for an oxygen fugacity around NNO+1. These T-H2O estimates are confirmed by empirical geothermometers based on experimental clinopyroxene and melt compositional trends. As for other Vesuvius eruptions, the most felsic part of the 1631 reservoir appears to have reached pre-eruptive leucite saturation, although a large amount of leucite microcrystals in the studied samples likely grew syn-eruptively. Our results confirm that magma storage conditions beneath Vesuvius became hotter, shallower, and more CO2-rich after the AD 79 Pompeii Plinian event.

Published
2020

25. Crystallization Kinetics of Alkali Feldspar in Peralkaline Rhyolitic Melts: Implications for Pantelleria Volcano

Author

Patrizia Landi, Fabio Arzilli, Paola Stabile, Alessandro Fabbrizio, Michael R. Carroll, Bruno Scaillet, and Eleonora Paris

Subjects
Explosive eruption, Chemistry, nucleation delay, Nucleation, Peralkaline rock, alkali feldspar, law.invention, peralkaline rhyolite, Pantelleria volcanic system, law, Rhyolite, Magma, General Earth and Planetary Sciences, lcsh:Q, crystallization kinetics, Crystallization, lcsh:Science, Supercooling, Petrology, Alkali feldspar
Abstract

Peralkaline rhyolites, associated with extensional tectonic settings, are medium to low viscosity magmas that often produce eruptive styles ranging from effusive to highly explosive eruptions. The role of pre-eruptive conditions and crystallization kinetics in influencing the eruptive style of peralkaline rhyolitic magmas has been investigated and debated considering equilibrium conditions. However, experimental constraints on the effect of disequilibrium in crystallization in such magmas are currently lacking in the literature. Therefore, we performed isobaric cooling experiments to investigate alkali feldspar crystallization kinetics in peralkaline rhyolitic melts. Experiments were performed under water-saturated, water-undersaturated and anhydrous conditions between 25 and 100 MPa, at 670-790 °C and with experimental durations ranging from 0.5 to 420 hours. Here we present the first data on crystallization kinetics of alkali feldspar, which is the main crystal phase in peralkaline rhyolitic melts, in order to improve our understanding of the evolutionary timescales of these melts and their ability to shift between effusive and explosive activity. Our experimental results indicate that the alkali feldspar nucleation delay can range from hours to several days as a function of undercooling and H2O content in the melt. Thus, a peralkaline rhyolitic magma can be stored at the pre-eruptive conditions for days without important variations of its crystal fraction. This suggests that crystallization may not necessarily play the main role in triggering fragmentation during explosive eruptions of peralkaline rhyolitic magmas.

Published
2020

26. High intensity ignimbritic activity in the Central sector of the Main Ethiopian Rift

Author

Zara Franceschini, Federico Sani, Abate Assen Melaku, Giacomo Corti, Stéphane Scaillet, Raffaello Cioni, Bruno Scaillet, Gaëlle Prouteau, University of Pisa - Università di Pisa, Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Paleontology, Rift, [SDU]Sciences of the Universe [physics], High intensity, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 15. Life on land, Geology, ComputingMilieux_MISCELLANEOUS
Abstract

The volcano-tectonic evolution of the Main Ethiopian Rift (MER) is punctuated with periods of intense silicic volcanism, characterized by large explosive caldera-forming eruptions and the production of several ignimbrite deposits. These volcanic paroxysms require large volume of evolved silicic magma accumulated in shallow chambers into the continental crust; however, the relations between magmatism and tectonics during rifting, and the influence of the distribution and timing of regional tectonics on the ascent of magma and its stalling in large magmatic reservoirs remain poorly defined.We present new geochronological data (40Ar/39Ar dataset of 29 samples) providing new constraints on the timing, evolution and characteristics of volcanism in the Central sector of the MER, where large ignimbrite deposits and remnants of several calderas testify the recurrence of silicic flare-ups. Specifically, we investigate in detail the eastern margin of the rift, where a voluminous, widespread, crystal-rich ignimbrite (Munesa Crystal Tuff, MCT) has been described. This deposit has been correlated to a thick ignimbrite occurring at the bottom of geothermal wells in the rift, pointing to a giant eruptive event attributed to a huge caldera structure, presumably buried beneath the rift floor. At least other two widespread ignimbrite units are present along the same margin for several tens of kilometres, testifying the high volcanicity of this sector of the MER.Our survey and analyses suggest that, at least in the eastern margin of the rift, activity was clustered in periods of large magma production and emission, resulting in the recurrence of intense volcanic phases interspersed with periods of rest of volcanism. Ignimbrites and other volcanic deposits occur in the investigated area, spanning an age interval from 3.5 Ma to as recent as 150 ka. The MCT emission, around 3.5 Ma, was followed, after a long quiescence, by an important phase with the emplacement of both mafic (lava flows and scoria cone) and evolved (ignimbrites) products between 1.9-1.6 Ma. After that, volcanism occurred more frequently, possibly with a lower amount of erupted magma and still alternating with quiescent periods, with volcanism clusters at ~ 1.3-1.2 Ma, ~ 0.8-0.7 Ma and ~ 0.3-0.2 Ma. This clustered volcanic activity will be compared with the episodic rifting of this sector of the Main Ethiopian Rift.

Published
2020

27. Understanding volcanic systems and their dynamics combining field and physical volcanology with petrology studies

Author

Marco Pistolesi, Raffaello Cioni, Bruno Scaillet, Massimo Pompilio, Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), University of Pisa - Università di Pisa, Istituto Nazionale di Geofisica e Vulcanologia – Sezione di Pisa (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), and ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011)

Subjects
geography, Experimental petrology, Data collection, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Volcanology, Hazard analysis, 010502 geochemistry & geophysics, 01 natural sciences, Field (geography), Volcano geology, Volcano, [SDU]Sciences of the Universe [physics], Physical volcanology, Dynamics of magmatic processes, Volcanic systems, Petrology, Intensive and extensive properties, Geology, 0105 earth and related environmental sciences
Abstract

International audience; Hazard assessment and definition of the eruptive scenarios at active volcanoes are mostly based on the elaboration of a large set of information collected with different disciplines and multiple analytical approaches. We discuss here how the reconstruction of the main processes acting at a volcano during its life should be based on the direct knowledge of its activity and products, in the view that each volcano is characterized by its own “personality.” Comparison with analogue volcanoes can add further important information on the expected variability of the different processes, but this should never substitute specific data collection at the volcano of interest. Field volcanology and petrology studies are the base for collecting large datasets on past, recent, and on-going activities and products. Based on these data, intensive and extensive physical parameters that control the dynamics of the activity can then be derived through focused physical volcanology investigations. Experimental petrology on the products of well-characterized eruptions finally returns a set of additional physical and compositional parameters that heavily contribute to enlarge our knowledge of the activity and evolution of a given volcano.

Published
2020

28. PHONOLITES, S-SOLUBILITY, AND SODALITE-HAÜYNE STABILITY

Author

Juan Andujar, Bruno Scaillet, Michael R. Carroll, and Camerino UniversityGeology Division

Subjects
Hauyne, Anhydrite, Chemistry, Analytical chemistry, chemistry.chemical_element, engineering.material, Sulfur, Silicate, chemistry.chemical_compound, Magma, engineering, Sodalite, Fugacity, Melt inclusions
Abstract

Sulfur solubility in magmas is known to strongly depend on such factors as melt composition, magma oxidation state (fO 2), P, and T. Unlike the more common magmatic volatiles (H 2 O, CO 2), sulfur can occur in a variety of forms, mainly controlled by magma oxidation state; the most important S-species in natural systems appear to be H 2 S, S 2 , and SO 2 as gas/fluid phase components, and S 2-, HS-, or SO 4 2-, as species dissolved in silicate melts. As a result of this complexity (and possible S-rich crystals), it is not always easy to interpret the significance of observed variations in S-emissions in active volcanic systems in terms of what is happening at depth. Furthermore, estimation of S-yields to the atmosphere in older volcanic eruptions requires accurate knowledge of not only how much S was in the pre-eruptive melt (e.g., via melt inclusions), but also an estimate of the mass and fugacities of sulfur species in any pre-eruptive magmatic fluid phase. We have conducted experiments on S-solubility in a sodic phonolitic melt composition (with, in wt% ~60 SiO 2 , 18.8 Al 2 O 3 , 10 Na 2 O, 5.5 K 2 O), at T= 930°C, P = 50-390 MPa, using mainly IHPV with controlled H2 fugacity and S fugacity roughly controlled by using samples with different amounts of S added as elemental S. Oxidation states range from approximately-3 to +3 log fO2 units relative to the NNO buffer. Depending on the amount of S added, the experiments range from nearly water saturated (low S added) to significantly H 2 O undersaturated (P(H 2 O) down to ~0.5*P total), with significant fugacities of H 2 S or SO 2 in the fluid phase, depending on experimental oxidation state. Sulfur solubilities in these alkali-rich phonolites are generally higher than those for dacitic to rhyolitic melts reported in other studies at similar fO 2 and fS 2 conditions. While previous studies have reported anhydrite stable in oxidized, S-rich andesitic to rhyolitic melts, in the studied phonolite we observe the stabilization of S-rich Sodalite (Hauyne) with up to ~12 wt% SO 3 at pressures up to 150 MPa, whereas at higher pressures the phonolitic melts coexist with an oxygen-rich Fe-SO immiscible liquid, but no anhydrite was observed. Additional work will help understand if Sodalite-Hauyne S (and Cl) contents in natural samples may be useful for estimating pre-eruptive S and Cl activities in magmas.

Published
2020

29. Role of inherited structure on granite emplacement: An example from the Late Jurassic Shibei pluton in the Wuyishan area (South China) and its tectonic implications

Author

Yan Chen, Saskia Erdmann, Hongsheng Liu, Bruno Scaillet, Guillaume Martelet, Bo Wang, Fangfang Huang, Michel Faure, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, State Key Laboratory for Mineral Deposits Research, Nanjing University (NJU), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), and ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011)

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Shibei Pluton, Magma emplacement, 010504 meteorology & atmospheric sciences, Pluton, Geochemistry, Classification of discontinuities, Structural inheritance, 010502 geochemistry & geophysics, 01 natural sciences, South China Block, Tectonics, Lineation, Gravity modelling, Geophysics, Group (stratigraphy), Magma, Period (geology), AMS, Bouguer anomaly, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

International audience; The Shibei pluton is a Late Jurassic granitic body in the South China Block (Fujian province), featured by macroscopically isotropic granite and undeformed margins, which are also characteristics for most of the Late Jurassic plutons in southeastern China. Our field observations, fabric investigations and gravity modelling allow us to decipher the internal structure, overall geometry, magma accumulation and emplacement processes of the Shibei pluton. Magnetic fabrics of the Shibei pluton can be divided into two distinct groups. The first one, observed in the southern-central part of the pluton, is characterized by high-angle to sub-vertical (54°-90°) NE-SW-striking magnetic foliations and variably plunging magnetic lineation. The second group, recognized in the northern part of the pluton, shows variably dipping (22°-88°) magnetic foliation, which generally strikes subparallel to pluton-country rock contacts, and irregularly oriented magnetic lineation. The Bouguer gravity modelling demonstrates that the pluton has a tabular geometry with a N-S-striking long axis, and a length-width-thickness ratio of ~32:8:1. The intrusion thickness gradually decreases from the southwest margin (ca. 2.5 km) to the northeast margin (ca. 0.5 km). Moreover, an undulating bottom with one or more convex intruding roots can be observed. Integrating published geochronological and regional tectonic data, we propose that the Shibei pluton was constructed by successive NE-SW-striking magma injections. Emplacement of early magma batches started in the SW part of the pluton by magma injection, which was guided by inherited structures produced by pre-emplacement tectonic events. Continuous magma injections were laterally accreted to earlier emplaced magma intrusions, and/or injected along lithological and/or structural discontinuities within the country rocks at upper crustal level without producing ductile deformation in the pluton-country rock contact zone. Our structural and fabric investigations indicate that the SE South China Block was not subjected to a major tectonic deformation during the Late Jurassic period.

Published
2020

30. Controls of magma chamber zonation on eruption dynamics and deposits stratigraphy: The case of El Palomar fallout succession (Tenerife, Canary Islands)

Author

María Jiménez-Mejías, Bruno Scaillet, Stéphane Scaillet, Joan Martí, Dario Pedrazzi, Silvia Zafrilla, Domenico M. Doronzo, Joan Andújar, Institute of Earth Sciences Jaume Almera, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Centro Geofísico de Canarias, Instituto Geografico Nacional, Magma - UMR7327, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Martí Molist, Joan [0000-0003-3930-8603], Pedrazzi, Dario [0000-0002-6869-1325], Doronzo, Domenico Maria [0000-0002-6866-8870], Martí Molist, Joan, Pedrazzi, Dario, and Doronzo, Domenico Maria

Subjects
010504 meteorology & atmospheric sciences, Geochemistry, Pyroclastic rock, Magma chamber, Eruption dynamics, Eruption column, 010502 geochemistry & geophysics, 01 natural sciences, Las Cañadas Edifice, Geochemistry and Petrology, El Palomar pumice fall, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, 0105 earth and related environmental sciences, geography, Explosive eruption, geography.geographical_feature_category, Tenerife, Teide, Magma chamber zonation, Geophysics, Volcano, 13. Climate action, Magma, Mafic, Geology
Abstract

Anticipating volcanic eruptions at central volcanoes require knowing how magma chambers prepare for new eruptions. Pre-eruptive processes that occur in such magma chambers are recorded in the products of these eruptions, so their characterisation in terms of magma composition and physics offers the clues to understand past eruptions and predict future ones. Here, we study the very well preserved pyroclastic succession of El Palomar Member (712 ± 41 ka), in Las Cañadas caldera, Teide, Canary Islands. This deposit resulted from a single explosive eruption of a phonolitic magma that started with a sustained eruption column (sub-plinian or plinian) that formed a massive, 40 m thick non-welded fallout deposit, progressively changing into a lower intensity fire fountain that deposited a 25 m thick fallout succession of non-welded to strongly welded pumices. Stratigraphic and petrological data suggest that this eruption was related to a thermally-compositionally zoned and relatively shallow magma chamber in which the arrival of a hotter and more mafic magma rapidly triggered the eruption. The studied deposit shows how this zoned structure was maintained during the whole process, which allows one to reconstruct what happened during the eruption. Comparison of this eruption with the current situation at Teide volcano alerts on the potential rapid preparation for new eruptions in the case that sufficient phonolitic magma was available in the shallow plumbing system of this active volcano if new inputs of deeper magma take place.

Published
2020

31. Storage conditions of the mafic and silicic magmas at Cotopaxi, Ecuador

Author

Patricia Mothes, Indira Molina, Joan Andújar, Bruno Scaillet, Caroline Martel, Michel Pichavant, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), instituto Geofísico, Escuela Politécnica Nacional (EPN), and European Project: 282759,EC:FP7:ENV,FP7-ENV-2011,VUELCO(2011)

Subjects
Rhyolite, Experimental petrology, 010504 meteorology & atmospheric sciences, Cotopaxi, Lava, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Silicic, Pyroclastic rock, 010502 geochemistry & geophysics, 01 natural sciences, Eruptive dynamics, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 0105 earth and related environmental sciences, Fractional crystallization (geology), biology, Andesites, Andesite, biology.organism_classification, Geophysics, [SDU]Sciences of the Universe [physics], 13. Climate action, Phenocryst, Scoria, Mafic, Geology
Abstract

International audience; The 2015 reactivation of the Cotopaxi volcano urges us to understand the complex eruptive dynamics of Cotopaxi for better management of a potential major crisis in the near future. Cotopaxi has commonly transitioned from andesitic eruptions of strombolian style (lava flows and scoria ballistics) or nuées ardentes (pyroclastic flows and ash falls) to highly explosive rhyolitic ignimbrites (pumiceous pyroclastic flows), which entail drastically different risks. To better interpret geophysical and geochemical signals, Cotopaxi magma storage conditions were determined via existing phase-equilibrium experiments that used starting materials chemically close to the Cotopaxi andesites and rhyolites. The results suggest that Cotopaxi's most mafic andesites (last erupted products) can be stored over a large range of depth from ~7 km to ≥16 km below the summit (pressure from ~200 to ≥400 MPa), 1000 °C, NNO +2, and contain 4.5–6.0±0.7 wt% H2O dissolved in the melt in equilibrium with ~30–40% phenocrysts of plagioclase, two pyroxenes, and Fe-Ti oxides. These mafic andesites sometimes evolve towards more silicic andesites by cooling to 950 °C. Rhyolitic magmas are stored at 200–300 MPa (i.e. ~7–11 km below the summit), 750 °C, NNO +2, and contain ~6–8 wt% H2O dissolved in a nearly aphyric melt (

Published
2018

32. Magmatic epidote in Archean granitoids of the Carajás Province, Amazonian craton, and its stability during magma rise and emplacement

Author

Luan Alexandre Martins de Sousa, Ingrid Roberta Viana da Cunha, Roberto Dall'Agnol, Bruno Scaillet, Federal University of Para - Universidade Federal do Para [Belem - Brésil], Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), and ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011)

Subjects
Archean, Pluton, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, 010503 geology, Epidotes, Magmatic epidote, 0105 earth and related environmental sciences, Earth-Surface Processes, geography, Sanukitoid, geography.geographical_feature_category, Viscosity, Carajás province, Geology, Crust, Epidote, Craton, [SDU]Sciences of the Universe [physics], Magma, engineering, Incremental growth, Dissolution
Abstract

International audience; In the Rio Maria and Sapucaia Domains of the Carajás Province, during the Mesoarchean, tonalite-trondhjemite-granodiorite (TTG) series (2.98–2.92 Ga; Colorado Trondhjemite) and sanukitoid rocks (∼2.87 Ga; Rio Maria Suite of Ourilândia do Norte) were formed. They were followed, in the Neoarchean (2.75–2.73 Ga), by numerous stocks of granitoids similar to A-type granites (Vila Jussara Suite). Despite the compositional differences between these granitoids, epidote is a mineral phase common to all of them, with pistacite contents of 26–29 mol% in TTGs, 22–33 mol% in sanukitoids and 25–30 mol% in Neoarchean granitoids. The study of the dissolution kinetics of Archean epidotes of the Carajás Province reveals that the partial dissolution time of their crystals was ∼4–10 years, with corresponding magma ascent rates of 4–8 km/year. Magma viscosities at liquidus temperature were estimated at 105.3 Pa s for TTG magma and 102.5 Pa s for sanukitoid magma, whereas monzogranitic magmas of the Vila Jussara Suite exhibited a viscosity of 104.4 Pa s. In contrast, the viscosity of tonalitic magma of the Vila Jussara Suite was 103.5 Pa s. The preservation of magmatic epidote in Archean granitoids requires that the plutons grew in an incremental way, similar to their Phanerozoic counterparts, with the stacking of small sill-dykes of about 100 m thickness each intruded in a rather cold crust, allowing fast cooling rates so as to prevent complete dissolution of epidote at the final emplacement level.

Published
2021

33. Phase equilibria of Pantelleria trachytes (Italy): constraints on pre-eruptive conditions and on the metaluminous to peralkaline transition in silicic magmas

Author

Bruno Scaillet, Nunzia Romengo, Silvio G. Rotolo, Pierangelo Romano, Joan Andújar, Ida Di Carlo, Pierangelo Romano, Joan Andujar, Bruno Scaillet, Nunzia Romengo, Ida di Carlo, Silvio G. Rotolo, Dipartimento DiSTeM, Università di Palermo, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo (INGV), and Istituto Nazionale di Geofisica e Vulcanologia

Subjects
trachyte, pantellerite, 010504 meteorology & atmospheric sciences, liquid line of descent, Analytical chemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Liquidus, engineering.material, metaluminous–peralkaline transition, 010502 geochemistry & geophysics, 01 natural sciences, Peralkaline rock, law.invention, Geochemistry and Petrology, law, experimental petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 62 pantellerite, Crystallization, peralkaline silicic magmatism, 0105 earth and related environmental sciences, Basalt, Felsic, Fractional crystallization (geology), Olivine, Settore GEO/07 - Petrologia E Petrografia, Geophysics, [SDU]Sciences of the Universe [physics], 13. Climate action, 63 liquid line of descent, metaluminous-peralkaline transition, engineering, Alkali feldspar, Geology, Pantelleria
Abstract

Pantelleria Island is the type locality of pantellerite, an iron and alkali-rich rhyolite (P.I=molar Na2O+K2O/Al2O3 >1.05). Peralkaline rhyolites (i.e pantellerite and comendite) and trachytes usually represent the felsic end-members in continental rift systems (e.g., Pantelleria, Tibesti, Ethiopia, Afar, Kenya, Bain and Range, South Greenland) and in oceanic sland settings (Socorro Is., Easter Is., Iceland and Azores). The origin of peralkaline rhyolites in the different tectonic settings is still a matter of debate and three hypotheses have been suggested: (a) crystal fractionation of alkali-basalt in a shallow reservoir to produce a trachyte which subsequently gives rise to a pantellerite (e.g., Barberi et al., 1975, Mungall & Martin 1995, Civetta et al., 1998,) (b) partial melting of cumulate gabbros to form a trachyte which then produces pantellerite (e.g., Lowestern & Mahood 1991; Bohrson & Reid 1997), (c) partial melting of different lithospheric sources fluxed by volatiles which add the excess alkalies to the melt (Bailey & Macdonald, 1975, 1987). Recent petrological work has helped to define the temperature range and redox conditions of pantellerite magmas (Scaillet & Macdonald 2001, 2003, 2006; White et al., 2005, 2009; Di Carlo et al., 2010,) as well as their pre-eruptive volatile contents (e.g., Gioncada & Landi 2010, Neave et al., 2012, Lanzo et al., 2013). In contrast little is known about the conditions of storage and evolution of the associated trachytes. At Pantelleria, trachytes and pantellerites constitute most of the outcropping rocks, the former being erupted dominantly as lava flows while pantellerites are erupted either explosively or effusively. We have experimentally investigated the phase relationship of two representative trachytes from Pantelleria island in order to shed light on their pre-eruptive conditions (pressure, temperature, H2Omelt, oxygen fugacity) and define their liquid lines of descent toward more evolved compositions. We have established the phase relationships over a P-T fO2-H2Omelt range of T=750-950°C, P=0.5-1.5 kbar, fO2=~FMQ and XH2Ofluid (H2O/H2O+CO2, in moles) between 1 and 0. By comparing the experimental phase assemblages, abundances and compositions with the natural products we set constraints on the storage conditions of trachytic magmas at Pantelleria and more generally, on the putative parent-daughter relationship between trachytic and pantelleritic magmas. Our results lay thebasis to understand the long debated petrological issue regarding the link 94 between silica oversaturated peralkaline and metaluminous magmas.

Published
2018

34. New aspects of magma storage and transfer

Author

Fabrice Gaillard, Bruno Scaillet, and Laurent Arbaret

Subjects
Global and Planetary Change, General Earth and Planetary Sciences, Petrology, Magma (computer algebra system), computer, Geology, computer.programming_language
Published
2019

35. Experimental constraints on intensive crystallization parameters and fractionation in A‐type granites: a case study on the Qitianling Pluton, South China

Author

Lei Xie, Saskia Erdmann, Fangfang Huang, Michel Faure, Jinchu Zhu, Yan Chen, Bo Wang, Hongsheng Liu, Rucheng Wang, Bruno Scaillet, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), State Key Laboratory for Mineral Deposits Research, Nanjing University (NJU), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), and ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011)

Subjects
South china, 010504 meteorology & atmospheric sciences, Phase equilibrium, Pluton, Geochemistry, Fractionation, 010502 geochemistry & geophysics, amphibole stability, 01 natural sciences, law.invention, Geophysics, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, law, [SDU]Sciences of the Universe [physics], experimental petrology, Earth and Planetary Sciences (miscellaneous), Ferroan (A-type) granite, Crystallization, phase equilibrium, emplacement conditions, South China, Geology, 0105 earth and related environmental sciences
Abstract

International audience; Phase equilibrium experiments are essential for robustly and accurately constraining the intensive parameters of magma systems and their fractionation history, which is particularly true for A‐type granites crystallized from H2O‐rich melts and at reducing conditions. Here, we constrain the crystallization conditions of the ferroan (A‐type), Sn‐mineralized Qitianling granite of South China which formed during a major event of crustal formation and reorganization in the Mesozoic. To characterize the magma system conditions and fractionation, we have carried out a series of experiments on three representative, amphibole‐bearing samples. The experiments were performed at 100‐700 MPa (mainly at 200 MPa and 300 MPa), at an fO2 of ~NNO‐1.3 (1.3 log unit below the Ni‐NiO buffer) or ~NNO+2.4, at 660°C to 900°C, and at variable H2Omelt (~3‐9 wt%). They show that the Qitianling magmas last crystallized at ≥300‐350 MPa, at a H2Omelt ≥6.5‐8.0 wt%, and that magmatic fO2 was ~NNO‐1.3±0.5 at above‐solidus conditions. Amphibole texture in the rocks suggests an early crystallization of this mineral, hence that water‐rich (≥4 wt% H2O in melt) conditions prevailed early during the magmatic evolution, prior to amphibole crystallization. At all investigated conditions, amphibole crystallization requires at least 5‐6 wt% dissolved H2O, being even absent in the more potassic composition. We interpret this as resulting from the elevated K2O content of the investigated compositions that inhibits amphibole crystallization in metaluminous granitic systems. The experimental liquid line of descent obtained at 200‐300 MPa mimics the geochemical trend expressed by the pluton suggesting that fractionation occurred in the upper crustal reservoir.

Published
2019

36. Chlorine and fluorine behavior in apatite-fluid-silicate melt systems

Author

Morgane Rondet, Bruno Scaillet, Michel Pichavant, Ida Di Carlo, POTHIER, Nathalie, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Magma - UMR7327, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC)

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics], [SDU.STU] Sciences of the Universe [physics]/Earth Sciences
Abstract

International audience; The fluctuation of halogen contents (Cl, F) of volcanic gases is potentially a good precursor signal of volcanic crises, yet the Cl and F behavior in magmas is complex due to the interplay between melt, fluid and halogens-bearing crystals. In magmatic rocks, Cl and F are the main constituents of apatite, an ubiquitous accessory magmatic mineral. As a result, apatite is increasingly being used as a geochemical tool for unravelling halogen behavior as it allows to record the fugacities of key volatile species. In this context, the behavior of Cl and F in coexisting apatite, fluids and a variety of silicate melts (rhyodacite, basalt, phonolite) has been investigated experimentally as a function of pressure, temperature, oxygen fugacity, and fluid composition. Experiments have been done using internally heated pressure vessels at 50-200 MPa, 800-1100 • C, fO 2 from NNO-1 to NNO+2 and starting fluid : Cl content between 0 and 15 wt%. Run products were analysed by SEM, EPMA and Raman spectroscopy. F and Cl contents of fluids were estimated by mass-balance. The results show that chlorine and fluorine partitioning in the apatite-melt-fluid system is dependent on all investigated parameters. In detail, for the rhyodacite composition, when the Cl content in starting fluid increases, the chlorine content of apatite increases (from 0.2 to 2.5 wt%) with the Cl content of melt (between 0.1 and 1 wt%) and fluid (between 0.2 and 22 wt%). When the pressure decreases (200 to 50 MPa with temperature and Cl content of the starting fluid being constant) the Cl content in apatite increases (2.2 to 2.7 wt%) with Cl content in melt (0.7-1wt%) while the bulk Cl content in fluid decreases (from 22 to 5 wt%). Cl and F always favor apatite relative to fluid and silicate melt, though in several run products, the behavior of F is difficult to evaluate owing to analytical errors for its measurement in glasses at low contents (

Published
2019

37. Gases as Precursory Signals: Experimental Simulations, New Concepts and Models of Magma Degassing

Author

Michel Pichavant, N. Le Gall, Bruno Scaillet, Magma - UMR7327, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Joachim Gottsmann, Jürgen Neuberg, Bettina Scheu, European Project: 282759,EC:FP7:ENV,FP7-ENV-2011,VUELCO(2011), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
event.disaster_type, Basalt, Disequilibrium degassing, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Volatile diffusion, Magma ascent, Gas compositions, 010502 geochemistry & geophysics, 01 natural sciences, Volcanic Gases, Volcano, 13. Climate action, Rhyolite, Magma, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, event, Decompression experiments, Solubility, Inclusion (mineral), Petrology, Saturation (chemistry), Geology, 0105 earth and related environmental sciences
Abstract

International audience; Volatile release during magma ascent in volcanic conduits (magma degassing) forms the basis for using volcanic gases as precursory signals. Recent high temperature high pressure experimental simulations have yielded results that challenge key assumptions related to magma degassing and are important for the interpretation of glass inclusion and gas data and for using volcanic gas as precursory signals. The experimental data show that, for ascent rates expected in natural systems, pure H2O basaltic melts will evolve mostly close to equilibrium when decompressed from 200 to 25 MPa. In the same way, degassing of H2O–S species evolves at near equilibrium, although this conclusion is limited by the number of S solubility data available for basaltic melts. However, degassing of CO2 is anomalous in all studies, whether performed on basaltic or rhyolitic melts. CO2 stays concentrated in the melt at levels far exceeding solubilities. The anomalous behaviour of CO2, when associated with near equilibrium H2O losses, yields post-decompression glasses with CO2 concentrations systematically higher than equilibrium degassing curves. Therefore, there is strong experimental support for disequilibrium degassing during ascent of CO2-bearing magmas. The existence of volatile concentration gradients around nucleated gas bubbles suggests that degassing is controlled by the respective mobilities (diffusivities) of volatiles within the melt. The recently formulated diffusive fractionation model reproduces the main characteristics, especially the volatile concentrations, of experimental glasses. The model also shows that the gas phase is more H2O-rich than expected at equilibrium because CO2 transfer toward the gas phase is hampered by its retention within the melt. However, only integrated gas compositions are calculated. Similarly, only bulk experimental fluid compositions are determined in recent experiments. Thus, constraints on the local gas phase are becoming necessary for the application to volcanoes. This stresses the need for the direct analysis of gas bubbles nucleated in decompression experiments. Pre-eruptive changes in volcanic CO2/SO2 and H2O/CO2 gas ratios are interpreted to reflect different pressures of gas-melt segregation in the conduit, an approach that assume gas-melt equilibrium. However, if disequilibrium magma degassing is accepted, the use of volatile saturation codes is no longer possible and caution must be exercised with the application of local equilibrium to volcanic gases. Future developments in the interpretation of gas data require progress from both sides, experimental and volcanological. One priority is to reduce the gap in scales between experiments and gas measurements.

Published
2019

38. Titanite: A potential solidus barometer for granitic magma systems

Author

Saskia Erdmann, Fangfang Huang, Rucheng Wang, Michel Faure, Kai Zhao, Bruno Scaillet, Yan Chen, Hongsheng Liu, Magma - UMR7327, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), State Key Laboratory for Mineral Deposits Research, and Nanjing University (NJU)

Subjects
010504 meteorology & atmospheric sciences, Granite, Geochemistry, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, Titanite, Solidus, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Barometer, law.invention, law, Pressure, Plagioclase, Amphibole, Quartz, 0105 earth and related environmental sciences, Global and Planetary Change, 13. Climate action, Magma, engineering, General Earth and Planetary Sciences, Geology, Biotite
Abstract

International audience; Constraining crystallization pressure and thus intrusion depth of granites in various geodynamic settings remains challenging, yet important to further our understanding of magma system and crustal evolution. We propose that titanite, which is a common accessory in metaluminous and weakly peraluminous granites, can be used as a barometer if it crystallized in magmatic, near-solidus conditions and in equilibrium with amphibole, plagioclase, K-feldspar, quartz, biotite, and magnetite ± ilmenite. Titanite Al2O3 increases with pressure (P) according to: P (in MPa) = 101.66 × Al2O3 in titanite (in wt%) + 59.013 (R2 = 0.83) with estimated uncertainties of ~±60 to ~±100 MPa for crystallization between ~150 and 400 MPa. We highlight that the current calibration dataset is limited, and that systematic experimental studies are needed to rigorously quantify the relation. The most important use of this empirical barometer will be for rocks in which amphibole is present but significantly altered, or in combination with amphibole barometry, as titanite can be easily dated by LA-ICP-MS.

Published
2019

39. On the relationship between oxidation state and temperature of volcanic gas emissions

Author

Bruno Scaillet, Clive Oppenheimer, Yves Moussallam, Department of Geography [Cambridge, UK], University of Cambridge [UK] (CAM), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Moussallam, Y [0000-0002-4707-8943], and Apollo - University of Cambridge Repository

Subjects
010504 meteorology & atmospheric sciences, Earth science, 3705 Geology, 010502 geochemistry & geophysics, great oxidation event, 01 natural sciences, Mantle (geology), Volcanic Gases, Geochemistry and Petrology, Mineral redox buffer, Oxidation state, Earth and Planetary Sciences (miscellaneous), [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, event, Great Oxidation, 0105 earth and related environmental sciences, Event, event.disaster_type, early Earth, geography, geography.geographical_feature_category, Great Oxygenation Event, 37 Earth Sciences, oxygen fugacity, early Earth redox, Early Earth, 3703 Geochemistry, Geophysics, Volcano, 13. Climate action, Space and Planetary Science, redox, 3706 Geophysics, volcanic degassing, Geology, Exosphere
Abstract

International audience; The oxidation state of volcanic gas emissions influences the composition of the exosphere and planetary habitability. It is widely considered to be associated with the oxidation state of the melt from which volatiles exsolve. Here, we present a global synthesis of volcanic gas measurements. We define the mean oxidation state of volcanic gas emissions on Earth today and show that, globally, gas oxidation state, relative to rock buffers, is a strong function of emission temperature, increasing by several orders of magnitude as temperature decreases. The trend is independent of melt composition and geodynamic setting. This observation may explain why the mean oxidation state of volcanic gas emissions on Earth has apparently increased since the Archean, without a corresponding shift in melt oxidation state. We argue that progressive cooling of the mantle and the cessation of komatiite generation should have been accompanied by a substantial increase of the oxidation state of volcanic gases around the onset of the Great Oxidation Event. This may have accelerated or facilitated the transition to an oxygen-rich atmosphere. Overall, our data, along with previous work, show that there are no single nor simple relationships between mantle-, magma- and volcanic gas-redox states.

Published
2019

40. Mantle plumes are oxidised

Author

Clive Oppenheimer, Marc-Antoine Longpré, Alejandra Gómez-Ulla, Bruno Scaillet, Catherine McCammon, Nial Peters, Emanuela Gennaro, Estelle Rose-Koga, Yves Moussallam, Raphaël Paris, Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Queens College [New York], City University of New York [New York] (CUNY), Bayerisches Geoinstitut (BGI), Universität Bayreuth, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Department of Geography [Cambridge, UK], University of Cambridge [UK] (CAM), Instituto Nazionale di Geofisica e Vulcanologie Sezione di Palermo, CNRS INSU-TelluS-SYSTER, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC)

Subjects
010504 meteorology & atmospheric sciences, oxygen fugacity degassing XANES melt inclusions mantle plumes, Geochemistry, 010502 geochemistry & geophysics, melt inclusions, 01 natural sciences, Mantle plume, Mantle (geology), Cape verde, mantle plumes 20 21, Geochemistry and Petrology, Mineral redox buffer, Hotspot (geology), Earth and Planetary Sciences (miscellaneous), 14. Life underwater, 0105 earth and related environmental sciences, Melt inclusions, Basalt, Subduction, oxygen fugacity, degassing, XANES, mantle plumes, Geophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Geology
Abstract

International audience; From oxic atmosphere to metallic core, the Earth's components are broadly stratified with respect to oxygen fugacity. A simple picture of reducing oxygen fugacity with depth may be disrupted by the accumulation of oxidised crustal material in the deep lower mantle, entrained there as a result of subduction. While hotspot volcanoes are fed by regions of the mantle likely to have incorporated such recycled material, the oxygen fugacity of erupted hotspot basalts had long been considered comparable to or slightly more oxidised than that of mid-ocean ridge basalt (MORB) and more reduced than subduction zone basalts. Here we report measurements of the redox state of glassy crystal-hosted melt inclusions from tephra and quenched lava samples from the Canary and Cape Verde Islands, that we can independently show were entrapped prior to extensive sulphur degassing. We find high ferric iron to total iron ratios (Fe3+/∑Fe) of up to 0.27–0.30, indicating that mantle plume primary melts are significantly more oxidised than those associated with mid-ocean ridges and even subduction zone. These results, together with previous investigations from the Erebus, Hawaiian and Icelandic hotspots, confirm that mantle upwelling provides a return flow from the deep Earth for components of oxidised subducted lithosphere and suggest that highly oxidised material accumulates or is generated in the lower mantle. The oxidation state of the Earth's interior must therefore be highly heterogeneous and potentially locally inversely stratified.

Published
2019

41. A radiography of Teide-Pico Viejo active volcanic complex, Tenerife, Canary Islands

Author

Joan Marti, Adelina Geyer, Dario Pedrazzi, Olaya Dorado, Joan Andújar, María Jimenez, Bruno Scaillet, European Commission, Institute of Earth Sciences Jaume Almera, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Magma - UMR7327, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC)

Subjects
[SDU]Sciences of the Universe [physics], Volcanology
Abstract

EGU General Assembly in Viena, Austria 7–12 April 2019, The Teide-Pico Viejo active volcanic complex (TPV) started to grow up about 180 ka ago at the interior of the Las Cañadas caldera, in the island of Tenerife. This volcanic depression originated by several vertical collapses of the former Tenerife central volcanic edifice (Las Cañadas edifice) following explosive emptying of high-level magma chambers. Occasional lateral collapses of the volcano flanks also occurred and modified the northern side of the caldera depression. These twin stratovolcanoes derive from the interaction of two different shallow magma systems that evolved simultaneously, giving rise to a complete series from basalt to phonolite The structure and volcanic stratigraphy of the TPV was initially established based on a detailed field and petrological studies. However, this volcanic complex has also been the focus of a number of geophysical studies that have provided a detailed imaging of its interior, including its plumbing system. The combination of these geophysical results with those from the previous stratigraphic and petrological studies, as well as the information gathered from the geology of the subhorizontal water galleries drilled on different sector of Tenerife, and from recent experimental petrology studies, offers a unique set of data that permits to construct a detailed 3D model of one of the largest intraplate oceanic volcanoes of the World. In this contribution we present the first 3D model of the TPV complex obtained by combining the available geological and geophysical data and discuss about the implications of the resulting model on volcano evolution, eruption dynamics, and potential for future activity., This contribution is part of the European Commission grant EVE (DG ECHO Ref: 826292)

Published
2019

42. Experimental and thermodynamic constraints on mineral equilibrium inpantelleritic magmas

Author

Bruno Scaillet, Silvio G. Rotolo, John C. White, Ida Di Carlo, Pierangelo Romano, Joan Andújar, Dipartimento di Scienze della Terra e del Mare [Palermo] (DiSTeM), Università degli studi di Palermo - University of Palermo, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Eastern Kentucky University, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo (INGV), Istituto Nazionale di Geofisica e Vulcanologia, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011), Romano P., Scaillet B., White J.C., Andujar J., Di Carlo I., and Rotolo S.G.

Subjects
Mineral, Olivine, 010504 meteorology & atmospheric sciences, Anorthoclase, Settore GEO/07 - Petrologia E Petrografia, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Liquidus, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Peralkaline rock, Experimental Petrology, Aenigmatite, [SDU]Sciences of the Universe [physics], Geochemistry and Petrology, Mineral Equilibria, engineering, Fayalite, Peralkaline magmas, Pantellerite, Amphibole, 0105 earth and related environmental sciences
Abstract

Crystallization experiments on two pantellerites from Pantelleria, Italy, provide new evidence for the relationships between mineral phases in pantelleritic rocks as well as the influence of temperature and redox conditions on mineral assemblages. Experiments were performed at 1 kbar with temperature ranging between 750–900°C, and fluid saturation conditions with XH2O (=H2O/H2O+CO2) between 0 and 1. Redox conditions were fixed at, or slightly below, the FMQ buffer. Results show that at temperature of 900 °C pantelleritic magmas are well above the liquidus regardless their water content; we also observed a decrease in liquidus temperature (800°C) with increasingly reducing conditions. Mineral assemblages of the natural rocks have been successfully reproduced, particularly the relationship between fayalite and aenigmatite, which appear to be strongly controlled by melt peralkalinity, temperature and redox conditions. This is the first time that fayalitic olivine have been synthetized in experimental studies on pantellerites, which was found to be stable only for temperatures ≥750°C while amphibole can be stable at temperatures as high as 800°C at high fF2. Experimental results have been compared with the composition of mineral phases as well as with the results obtained from mineral equilibrium, geothermometry, and oxygen barometry studies on pantelleritic lava and tuffs from Pantelleria (Italy), Eburru (Kenya) and Menengai (Kenya). Petrological characteristics appear similar at different locations worldwide, with typical assemblages of anorthoclase and sodian clinopyroxene with variable fayalite, aenigmatite, Fe-Ti oxides and amphibole.

Published
2020

43. Generation Conditions of Dacite and Rhyodacite via the Crystallization of an Andesitic Magma. Implications for the Plumbing System at Santorini (Greece) and the Origin of Tholeiitic or Calc-alkaline Differentiation Trends in Arc Magmas

Author

Michel Pichavant, Timothy H. Druitt, Joan Andújar, Bruno Scaillet, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Laboratoire Magmas et Volcans (LMV), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), INSITU project of region Centre, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), ANR-08-BLAN-0249,STOMIXSAN,Stockage et mélange de magmas au Santorin(2008), ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Rhyodacite, liquid line of descent, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Magma chamber, 010502 geochemistry & geophysics, Dacite, 01 natural sciences, Geochemistry and Petrology, experimental petrology, phase equilibria, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Phreatomagmatic eruption, 0105 earth and related environmental sciences, Santorini, andesite, Andesite, tholeiitic, calc-alkaline, Geophysics, [SDU]Sciences of the Universe [physics], 13. Climate action, Magma, Magmatism, Phenocryst, Geology
Abstract

International audience; Andesitic arc volcanism is the most common type of subduction-related magmatism on Earth. How these melts are generated and under which conditions they evolve towards silica-rich liquids is still a matter of discussion. We have performed crystallization experiments on a representative andesite sample from the Upper Scoriae 1 (USC-1) eruption of Santorini (Greece) with the aim of understanding such processes. Experiments were performed between 1000 and 900 °C, in the pressure range 100–400 MPa, at fO2 from QFM (quartz–fayalite–magnetite) to NNO (nickel–nickel oxide) + 1·5, with H2Omelt contents varying from saturation to nominally dry conditions. The results show that the USC-1 andesitic magma was generated at 1000 °C and 12–15 km depth (400 MPa), migrated to shallower levels (8 km; 200 MPa) and intruded into a partially crystallized dacitic magma body. The magma cooled to 975 °C and generated the phenocryst assemblage and compositional zonations that characterize the products of this eruption. An injection of basaltic magma problably subsequently triggered the eruption. In addition to providing the pre-eruptive conditions of the USC-1 magma, our experiments also shed light on the generation conditions of silica-rich magmas at Santorini. Experimental of runs performed at fO2 ∼ NNO + 1 (± 0·5) closely mimic the compositional evolution of magmas at Santorini whereas those at reduced conditions (QFM) do not. Glasses from runs at 1000–975 °C encompass the magma compositions of intermediate-dominated eruptions, whereas those at 950–900 °C reproduce the silicic-dominated eruptions. Altogether, the comparison between our experimental results and natural data for major recent eruptions from Santorini shows that different magma reservoirs, located at different levels, were involved during highly energetic events. Our results suggest that fractionation in deep reservoirs may give rise to magma series with a tholeiitic signature whereas at shallow levels calc-alkaline trends are produced.

Published
2016

44. The Influence of Redox State On Mica Crystallization In Leucogranitic and Pegmatitic Liquids

Author

Arnaud Villaros, Mohamed Lahlafi, Michel Pichavant, Sarah Deveaud, Bruno Scaillet, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), and ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010)

Subjects
010504 meteorology & atmospheric sciences, Analytical chemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Mineralogy, pegmatite, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, micas, law.invention, Geochemistry and Petrology, law, Crystallization, leucogranite, Pegmatite, 0105 earth and related environmental sciences, Muscovite, experiments, Siderophyllite, Phengite, Leucogranite, redox state, [SDU]Sciences of the Universe [physics], 13. Climate action, engineering, Mica, Biotite, Geology
Abstract

International audience; Experiments have been performed both on a peraluminous leucogranitic (DK89) and a F-, Li-, P-rich pegmatitic (B2) melt to constrain the stability of micas in evolved crustal silicic magmas and refine mica-melt partition coefficients for F, Li, and Be. The experiments were conducted in parallel in two fO2 ranges, “oxidizing” (NNO +1 to +3) and “reducing” (NNO –1.6 to –1.4). One two-stage reducing-oxidizing experiment was conducted in a vessel fitted with a H2-permeable Shaw-type membrane. The approach toward equilibrium was tested by imposing long experimental durations and combining mica crystallization experiments with mica dissolution experiments using mica seeds. Experimental micas and melts were analyzed for major elements by electron microprobe and for light elements by nuclear microprobe. At 3 kbar, 620 °C, and under oxidizing conditions, B2 crystallized only muscovite, the biotite seeds reacting to form a new mica intermediate between phengite and Li-rich phengite. Under reducing conditions, biotite (siderophyllite composition) appeared as the stable mica. The two-stage experiment yielded a composite mica assemblage with siderophyllite cores mantled by muscovite rims. At 3.5–3.8 kbar, 720 °C, and under oxidizing conditions, DK89 crystallized only aluminous biotite and muscovite seeds reacted to form biotite-bearing assemblages; muscovite appeared together with biotite at 700 °C. Under reducing conditions, Al-rich biotite is also the stable mica at 720 °C. Partition coefficients show that F and Li are preferentially incorporated in biotite rather than in muscovite, the opposite as for Be. Biotite fractionation buffers the F and increases the Li and Be contents of the residual melt. Muscovite increases the Li content of the melt and has little influence on F and Be concentrations. Our experiments reproduce mica assemblages and compositions typical of Variscan pegmatites and leucogranites, yet very Li-rich micas (e.g., lepidolites) were not obtained. The results stress the differential influence of fO2 on mica stability in moderately and highly fractionated crustal melts. Mica crystallization in leucogranites does not appear to be strongly dependent on fO2. In contrast, a very strong influence of fO2 on stable mica assemblages is demonstrated for the pegmatitic melt. The reducing experiments emphasize the existence of a stability field for biotite in melts poor in Fe, Mg, and Ti. If fO2 is reducing, biotite must crystallize in moderately to highly evolved peraluminous crustal melts. In contrast, the crystallization of muscovite as the sole mica in evolved crustal melts constitutes an indicator of oxidizing fO2. Such an oxidizing evolution that deviates from classical buffered T-logfO2 trajectories is the consequence of a mechanism of magma “self-oxidation” that is proposed to result from dissociation of H2O in the melt.

Published
2016

45. The solubility of sulfur in hydrous basaltic melts

Author

Priscille Lesne, Michel Pichavant, Bruno Scaillet, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Italian Civil Defense INGV-DPC projects, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), European Project: 282759,EC:FP7:ENV,FP7-ENV-2011,VUELCO(2011), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Analytical chemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, chemistry.chemical_element, Mineralogy, Electron microprobe, engineering.material, Basaltic melts, 010502 geochemistry & geophysics, 01 natural sciences, chemistry.chemical_compound, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Fugacity, Solubility, Pyrrhotite, Dissolution, 0105 earth and related environmental sciences, Geology, Sulfur, Silicate, chemistry, [SDU]Sciences of the Universe [physics], 13. Climate action, engineering, Experiments, Saturation (chemistry)
Abstract

Experiments were performed to determine the sulfur solubilities of hydrous basalts from Vesuvius, Etna and Stromboli (Italy). The melts were equilibrated at 1050 and 1200 °C with H 2 O and sulfur (added as pyrrhotite), and at pressures ranging from 250 to 2000 bar. Most experiments were performed under oxidising conditions (NNO + 2), and a few under reducing conditions (NNO − 1), with melt water contents of 0.5–3.5 wt.%. Sulfur contents in glasses were determined by electron microprobe and range from 860 up to 6700 ppm. No compositional effect is found between the three alkali basaltic melts. The fugacities of S-bearing species were derived using an MRK equation of state applied to an O–H–S fluid, knowing H 2 and H 2 O fugacities, and range from 50 up to 3000 bar. A thermodynamic species-based model is derived from our results along with available data in the literature, assuming that sulfur dissolution results from the additive contributions of both H 2 S and SO 2 dissolution reactions. Compared to similar models developed for silicic melts, basalt compositions requires the incorporation of an Fe term, which accounts for the strong association between Fe and S in silicate melts, and considers the elevated Fe content of mafic melts. The model shows that, at any fixed f S 2 , the sulfur solubility in hydrous basalt displays a pronounced minimum around NNO, the position of which depends on temperature. The minimum in sulfur solubility coincides with the redox range were the abundance of S 2 in the fluid reaches its maximum compared to either H 2 S or SO 2 species. Such a minimum in solubility is in agreement with experimental constraints at 1 bar under carefully controlled f O 2 and f S 2 . Calculated proportions of dissolved species in the melt depend on the prevailing f S 2 and f O 2 , being in general agreement with available spectroscopic models. Calculations of gas saturation pressures, which classically consider only H 2 O and CO 2 dissolved volatiles, are strongly affected by S-bearing species. At f O 2 close to, or higher than, NNO + 1, omission of sulfur species may result in underestimates of gas saturation pressures of 1 kbar or more. The same happens at f O 2 below NNO − 1.

Published
2015

46. Experimental mixing of hydrous magmas

Author

Bruno Scaillet, Joan Andújar, Laurent Arbaret, Rémi Champallier, Mickael Laumonier, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), and ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011)

Subjects
Basalt, geography, Felsic, geography.geographical_feature_category, Pluton, mingling, deformation, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Mineralogy, Stratification (water), Geology, Atmospheric temperature range, shearing, hydrous, Volcano, [SDU]Sciences of the Universe [physics], 13. Climate action, Geochemistry and Petrology, enclave, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Igneous differentiation, Magma mixing, Mafic, texture
Abstract

International audience; Deformation experiments involving hydrous magmas of different compositions (basalt andhaplotonalite) have been performed in a Paterson press at 300 MPa, in the temperature range600°C-1020°C, with water-saturated melts, during 2-4 hours. Prior to deformation the twoend-member magmas were annealed at either 950°C or 1000°C, yielding magmas with crystalcontents in the range 31-53 wt% and 2 sets of viscosity contrasts. Under the experimentalconditions investigated (i.e. moderate shear rates 950°C. In the temperature range 950-985°C a few mixing and minglingtextures occur, though both end-members essentially retain their physical integrity. It is onlyat, or above, 1000°C that a dramatic jump in mingling efficiency happens, corresponding to acrystal fraction of 45 vol%. Textures include entrainment of mafic crystals into the felsicmagma, mafic-felsic banding, enclave formation, diffusion-induced interface, the latter only over limited distances (< 300 microns) due to the short run durations. In the most strainedparcels of interacting magmas, complex mixing/mingling textures were produced, similar tothose observed in volcanic and plutonic rocks in arc settings. The experiments show thatmixing between hydrous felsic and mafic magmas takes place at around 1000°C, atemperature which is almost 200°C lower than mixing under dry conditions. Magma mixingis commonly invoked as a trigger for volcanic eruptions; our experiments suggest that sucheruptions can be driven by small (~15°C) temperature fluctuation in the reservoir. Our resultsalso suggest that slow replenishment of a felsic reservoir by mafic inputs will likely result instratification between end-members rather than in a homogeneous mixture.

Published
2015

47. Melting conditions in the modern Tibetan crust since the Miocene

Author

Guillaume Richard, Martyn Unsworth, Xiaosong Yang, Fabrice Gaillard, Jinyu Chen, Mickael Laumonier, Bruno Scaillet, Laurent Jolivet, Leila Hashim, Arnaud Villaros, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration (CEA)-China Earthquake Administration (CEA), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Earth and Atmospheric Sciences [Edmonton], University of Alberta, University of Minnesota [Twin Cities] (UMN), University of Minnesota System, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), ANR-15-CE01-0001,VARPEG,Les pegmatites varisques: un nouveau type de ressources minérales(2015), European Project: 279790,EC:FP7:ERC,ERC-2011-StG_20101014,ELECTROLITH(2011), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Minnesota [Twin Cities], ANR-10-LABX-100-01/10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), ANR-15-CE01-0001,VARPEG, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), and Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
Complex field, geography, Multidisciplinary, Plateau, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Granitic rock, Science, Geochemistry, General Physics and Astronomy, Crust, General Chemistry, 010502 geochemistry & geophysics, 01 natural sciences, Article, General Biochemistry, Genetics and Molecular Biology, Tectonics, 13. Climate action, lcsh:Q, lcsh:Science, Geology, 0105 earth and related environmental sciences
Abstract

Abundant granitic rocks exposed in ancient mountain belts suggest that crustal melting plays a major role in orogenic processes. However, complex field relations and superposition of multiple tectonic events make it difficult to determine the role of melting in orogenesis. In contrast, geophysical measurements image present-day crustal conditions but cannot discriminate between partial melt and aqueous fluids. Here we connect pressure–temperature paths of Himalayan Miocene crustal rocks to the present-day conditions beneath the Tibetan plateau imaged with geophysical data. We use measurements of electrical conductivity to show that 4–16% water-rich melt is required to explain the crustal conductivity in the north-western Himalaya. In southern Tibet, higher melt fractions >30% reflect a crust that is either fluid-enriched (+1% H2O) or hotter (+100 °C) compared to the Miocene crust. These melt fractions are high enough for the partially molten rocks to be significantly weaker than the solid crust., Crustal melting may play a fundamental role in orogenic processes, but quantifying crustal melt remains difficult. Here, the authors combine pressure-temperature paths, electrical conductivity and geophysical data to elucidate the melting conditions in Tibet since the Miocene.

Published
2018

48. Incremental Emplacement of the Late Jurassic Midcrustal, Lopolith-Like Qitianling Pluton, South China, Revealed by AMS and Bouguer Gravity Data

Author

Jinchu Zhu, Nicole le‐Breton, Liangshu Shu, Saskia Erdmann, Yan Chen, Hongsheng Liu, Guillaume Martelet, Rucheng Wang, Bo Wang, Fangfang Huang, Michel Faure, Bruno Scaillet, State Key Laboratory for Mineral Deposits Research, Nanjing University (NJU), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, and Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)

Subjects
geography, geography.geographical_feature_category, Lopolith, 010504 meteorology & atmospheric sciences, Pluton, Crust, 010502 geochemistry & geophysics, 01 natural sciences, Laccolith, Geophysics, Sill, Space and Planetary Science, Geochemistry and Petrology, [SDU]Sciences of the Universe [physics], Magma, Magmatism, Earth and Planetary Sciences (miscellaneous), Petrology, Bouguer anomaly, Geology, 0105 earth and related environmental sciences
Abstract

International audience; Modes of magma emplacement may provide key information on geodynamic-tectonic settings of magmatism, when the threshold of magma volume and duration of emplacement process is crossed, brittle/ductile crustal deformation behavior, and volumes and rates of magma transfer in the crust. The majority of upper-crustal granitic intrusions are incrementally emplaced as laccoliths or sills, while midcrustal or deeper-level granitic intrusions appear to be predominantly emplaced as sills or lopoliths, but relatively few examples have been studied. We present a case study on the Jurassic Qitianling pluton from South China, which was constructed in the upper part of the middle crust (at a depth of ~10-15 km). To characterize its emplacement mechanism and evolution, we have combined field and microscopic observations, Anisotropy of Magnetic Susceptibility measurements and Bouguer gravity anomaly modeling. The main findings are (1) the generally undeformed granite-country rock contacts with a narrow thermal aureole, (2) irregularly wavy and gradational contacts between the main granite facies, (3) dominant subhorizontal magnetic fabrics in the granites with a scattered magnetic foliation, (4) rare occurrence of dykes, and (5) a subcircular surface and lopolith-like pluton geometry. Accordingly, we suggest that the Qitianling pluton forms an ~25-km wide and ~5-km thick lopolith that was incrementally emplaced during a period of tectonic quiescence, most likely by under-accretion of multiple magma sheets deflected from magma pulses that ascended through pipe-like channels. The mineralogical and compositional variation of the pluton may be the result of in situ fractionation, fractionation at deeper crustal level, or variation in source-derived melt compositions.

Published
2018

49. Publisher Correction: Melting conditions in the modern Tibetan crust since the Miocene

Author

Mickael Laumonier, Guillaume Richard, Xiaosong Yang, Bruno Scaillet, Fabrice Gaillard, Leїla Hashim, Arnaud Villaros, Laurent Jolivet, Martyn Unsworth, Jinyu Chen, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), China Earthquake Administration (CEA), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre de Paris (iSTeP), and Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Multidisciplinary, Published Erratum, media_common.quotation_subject, Science, General Physics and Astronomy, Crust, General Chemistry, Geodynamics, Legend, General Biochemistry, Genetics and Molecular Biology, GeneralLiterature_MISCELLANEOUS, Paleontology, [SDU]Sciences of the Universe [physics], ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, lcsh:Q, lcsh:Science, Geology, media_common
Abstract

International audience; The original PDF version of this Article contained an error in which Fig. 3 and its legend were omitted and Equations 5 and 6 contained errors.This has been corrected in the PDF version of the Article. The HTML version was correct from the time of publication.

Published
2018

50. The role of melt composition on aqueous fluid vs. silicate melt partitioning of bromine in magmas

Author

Bruno Scaillet, Tamsin A. Mather, Emanuela Gennaro, Giada Iacono-Marziano, David M. Pyle, Etienne Deloule, Alessandro Aiuppa, Antonio Paonita, Anita Cadoux, Cadoux, Anita, Iacono-Marziano, Giada, Scaillet, Bruno, Aiuppa, Alessandro, Mather, Tamsin A., Pyle, David M., Deloule, Etienne, Gennaro, Emanuela, Paonita, Antonio, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Dipartimento DiSTeM, Università di Palermo, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Department of Earth Sciences [Oxford], University of Oxford [Oxford], Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), and ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010)

Subjects
atmospheric chemistry, 010504 meteorology & atmospheric sciences, bromine, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Silicic, arc magma, 010502 geochemistry & geophysics, 01 natural sciences, fluid/melt partitioning, Volcanic Gases, chemistry.chemical_compound, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), event, Petrology, Geophysic, 0105 earth and related environmental sciences, Melt inclusions, event.disaster_type, Basalt, Andesite, Settore GEO/07 - Petrologia E Petrografia, degassing, Silicate, arc magmas, Settore GEO/08 - Geochimica E Vulcanologia, Geophysics, chemistry, 13. Climate action, Space and Planetary Science, Magma, Mafic, Geology
Abstract

International audience; Volcanogenic halogens, in particular bromine, potentially play an important role in the ozone depletion of the atmosphere. Understanding bromine behaviour in magmas is therefore crucial to properly evaluate the contribution of volcanic eruptions to atmospheric chemistry and their environmental impact. To date, bromine partitioning between silicate melts and the gas phase is very poorly constrained, with the only relevant experimental studies limited to investigation of synthetic melt with silicic compositions. In this study, fluid/melt partitioning experiments were performed using natural silicate glasses with mafic, intermediate and silicic compositions. For each composition, experiments were run with various Br contents in the initial fluid (H2O–NaBr), at T–P conditions representative of shallow magmatic reservoirs in volcanic arc contexts (100–200 MPa, 900–1200 °C). The resulting fluid/melt partition coefficients (DBrf/m) are: 5.0 ± 0.3 at 1200 °C–100 MPa for the basalt, 9.1 ± 0.6 at 1060 °C–200 MPa for the andesite and 20.2 ± 1.2 at 900 °C–200 MPa for the rhyodacite. Our experiments show that DBrf/m increases with increasing SiO2 content of the melt (as for chlorine) and suggest that it is also sensitive to melt temperature (increase of DBrf/m with decreasing temperature). We develop a simple model to predict the S–Cl–Br degassing behaviour in mafic systems, which accounts for the variability of S–Cl–Br compositions of volcanic gases from Etna and other mafic systems, and shows that coexisting magmatic gas and melt evolve from S-rich to Cl–Br enriched (relative to S) upon increasing degree of degassing. We also report first Br contents for melt inclusions from Etna, Stromboli, Merapi and Santorini eruptions and calculate the mass of bromine available in the magma reservoir prior to the eruptions under consideration. The discrepancy that we highlight between the mass of Br in the co-existing melt and fluid prior to the Merapi 2010 eruption (433 and 73 tons, respectively) and the lack of observed BrO (from space) hints at the need to investigate further Br speciation in ‘ash-rich’ volcanic plumes. Overall, our results suggest that the Br yield into the atmosphere of cold and silicic magmas will be much larger than that from hotter and more mafic magmas.

Published
2018

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