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We develop and implement a novel fast bootstrap for dependent data. Our scheme is based on the i.i.d. resampling of the smoothed moment indicators. We characterize the class of parametric and semi-parametric estimation problems for which the method is valid. We show the asymptotic refinements of the proposed procedure, proving that it is higher-order correct under mild assumptions on the time series, the estimating functions, and the smoothing kernel. We illustrate the applicability and the advantages of our procedure for Generalized Empirical Likelihood estimation. As a by-product, our fast bootstrap provides higher-order correct asymptotic confidence distributions. Monte Carlo simulations on an autoregressive conditional duration model provide numerical evidence that the novel bootstrap yields higher-order accurate confidence intervals. A real-data application on dynamics of trading volume of stocks illustrates the advantage of our method over the routinely-applied first-order asymptotic theory, when the underlying distribution of the test statistic is skewed or fat-tailed.

During the Cenozoic, the Menderes Massif (western Turkey) records several tectonic and thermal events from subduction to collision, then back-arc extension. But the detailed timing of the succession of different P-T regimes and deformation until today remains debated. To address this, we targeted the main shear zones, providing for the first time a full picture of the 40Ar/39Ar system across the massif. This approach is combined with Tmax, and P-T estimates tied to kinematic-structural data. Extensive sampling along the large top-S Selimiye shear zone allows constraining the deformation at least between 44 and 33 Ma. This shear zone acted as a thrust and was active under HT-MP (530 - 590 °C and 8.5 - 10 kbar). Conversely, the top-S South Menderes Detachment System is associated with a younging of 40Ar/39Ar ages related to exhumation and strain localization during the Late Oligo-Miocene in the Central Menderes Massif. The Bozdağ top-S shear zone then allowed the exhumation of the Bayındır nappe at ~ 21 Ma from high-temperature metamorphic conditions (590 °C). Based on these new elements, we propose for the first time a detailed scenario of the Menderes Massif evolution from the Late Cretaceous to the Present. We finally discuss why the Menderes Massif belongs currently to the regions with the highest geothermal potential in the world. We propose that geothermal activity here is not of magmatic origin but rather associated with active extensional tectonics (detachments) related to the Aegean slab dynamics (i.e., slab retreat and tearing).

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 SO2 output amounts to 1.15 ± 0.48 Tg/yr. We estimate an additional time-averaged SO2 yield of 0.12-0.54 Tg/yr for explosive eruptions, indicating a total SO2 inventory of 1.27-1.69 Tg/yr for Indonesian. This is comparatively modest—individual volcanoes such as Etna have sustained higher fluxes. To understand this paradox, we compare the geodynamic, petrologic, magma dynamical and shallow magmatic-hydrothermal processes that influence the sulfur transfer to the atmosphere. Results reinforce the idea that sulfur-rich eruptions reflect long-term accumulation of volatiles in the reservoirs.

International audience; This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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)

Using target-matching techniques combining Ar40/Ar39 crystal-mapping with elemental mapping and high-resolution electron microscopy, this study investigates the Ar40 behavior in very-slowly cooled muscovite from the Harney Peak Granite (HPG, South Dakota, USA). Detailed age mapping along (001) in single crystals from different localities of the HPG documents age gradients in excess of ∼ 300–400 m.y., with conspicuous internal Ar40/Ar39 zoning. This suggests (001) layer-parallel Ar40 transport driven by diffusion, consistent with previous Ar40/Ar39 crystal-mapping studies. The age distribution pattern is complex, however, and defines a mosaic of sub-grain domains with more retentive core zones, broadly ∼ 250–300 μm across, separated by zones of high diffusivity varying in shape and extent. The maximum ages preserved in the core domains are independent of their size but vary linearly with the bulk areal extent of the peripheral (or surrounding) high-diffusivity zones. Spatial Ar40/Ar39 relationships inside each grain point to a mechanism of multipath continuum-diffusion interaction between subdomains across the whole crystal, rather than via discrete non-interracting domains such as in K-feldspars. A close spatial correlation exists between younger ages, Na-depleted (K-enriched) zones, and density of microstructural defects. These defects, identified as lenticular voids and basal partings (< 100 nm–long), developed in response to inward K ↔ Na interdiffusion during late-magmatic stages, in the absence of deformation. Coupled variations in density of microstructural defects and Na–K interchange are inferred to control the bulk diffusion-domain structure of HPG muscovite. Quantitative diffusion modeling of coupled compositional–defect–isotopic variations indicates that Ar40 diffusivity may be enhanced by up to six orders of magnitude in defect-controlled high-diffusivity zones relative to less defective (pristine) domains. On the other hand, empirical diffusivity estimates required to preserve the core ages are commensurate with diffusion estimates independently derived from recent atomistic simulations., Work supported by LABEX grant VOLTAIRE (ANR-10-LABX-100-01), the Région Centre grant ARGON, and the EQUIPEX grant PLANEX (ANR-11-EQPX-0036). J. Nteme is supported by a post-doctoral grant from the project LABEX-VOLTAIRE.

In statistics, samples are drawn from a population in a data- generating process (DGP). Standard errors measure the uncer- tainty in sample estimates of population parameters. In sci- ence, evidence is generated to test hypotheses in an evidence- generating process (EGP). We claim that EGP variation across researchers adds uncertainty: non-standard errors. To study them, we let 164 teams test six hypotheses on the same sam- ple. We find that non-standard errors are sizeable, on par with standard errors. Their size (i) co-varies only weakly with team merits, reproducibility, or peer rating, (ii) declines significantly after peer-feedback, and (iii) is underestimated by participants.

We develop inferential tools for latent factor analysis in short panels. The pseudo maximum likelihood setting under a large cross-sectional dimension $n$ and a fixed time series dimension $T$ relies on a diagonal $T \times T$ covariance matrix of the errors without imposing sphericity or Gaussianity. We outline the asymptotic distributions of the latent factor and error covariance estimates as well as of an asymptotically uniformly most powerful invariant (AUMPI) test based on the likelihood ratio statistic for tests of the number of factors. We derive the AUMPI characterization from inequalities ensuring the monotone likelihood ratio property for positive definite quadratic forms in normal variables. An empirical application to a large panel of monthly U.S. stock returns separates date after date systematic and idiosyncratic risks in short subperiods of bear vs. bull market based on the selected number of factors. We observe an uptrend in idiosyncratic volatility while the systematic risk explains a large part of the cross-sectional total variance in bear markets but is not driven by a single factor. We also find that observed factors, scaled or not, struggle spanning latent factors. Rank tests reveal that observed factors struggle spanning latent factors with a discrepancy between the dimension of the two factor spaces decreasing over time.

We develop a flexible and bias-adjusted approach to jointly examine skill, scalability, and value added across individual funds. We find that skill and scalability (i) vary substantially across funds, and (ii) are strongly related as great investment ideas are difficult to scale up. The combination of skill and scalability produces a value added that (i) is positive for the majority of funds, and (ii) approaches its optimal level after an adjustment period possibly due to investors' learning. These results are consistent with theoretical models in which funds are skilled and able to extract economic rents from capital markets.

International audience; Using target-matching techniques combining Ar/Ar crystal-mapping with elemental mapping and high-resolution electron microscopy, this study investigates the Ar behavior in very-slowly cooled muscovite from the Harney Peak Granite (HPG, South Dakota, USA). Detailed age mapping along (001) in single crystals from different localities of the HPG documents age gradients in excess of 300400 m.y., with conspicuous internal Ar/Ar zoning. This suggests (001) layer-parallel Ar transport driven by diffusion, consistent with previous Ar/Ar crystal-mapping studies. The age distribution pattern is complex, however, and defines a mosaic of sub-grain domains with more retentive core zones, broadly 250300 m across, separated by zones of high diffusivity varying in shape and extent. The maximum ages preserved in the core domains are independent of their size but vary linearly with the bulk areal extent of the peripheral (or surrounding) high-diffusivity zones. Spatial Ar/Ar relationships inside each grain point to a mechanism of multipath continuum-diffusion interaction between subdomains across the whole crystal, rather than via discrete non-interracting domains such as in K-feldspars. A close spatial correlation exists between younger ages, Na-depleted (K-enriched) zones, and density of microstructural defects. These defects, identified as lenticular voids and basal partings ( 100 nmlong), are developed in response to inward K Na interdiffusion during late-magmatic stages, in the absence of deformation. Coupled variations in density of microstructural defects and NaK interchange are inferred to control the bulk diffusion-domain structure of HPG muscovite. Quantitative diffusion modeling of coupled compositionaldefectisotopic variations indicates that Ar diffusivity may be enhanced by up to six orders of magnitude in defect-controlled high-diffusivity zones relative to less defective (pristine) domains. On the other hand, empirical diffusivity estimates required to preserve the core ages are commensurate with diffusion estimates independently derived from recent atomistic simulations.

This paper proposes an original approach for backtesting systemic risk measures. This backtesting approach makes it possible to assess the systemic risk measure forecasts used to identify the financial institutions that contribute the most to the overall risk in the financial system. Our procedure is based on simple tests similar to those generally used to backtest the standard market risk measures such as value-at-risk or expected shortfall. We introduce a concept of violation associated with the marginal expected shortfall (MES), and we define unconditional coverage and independence tests for these violations. We can generalize these tests to any MES-based systemic risk measures such as the systemic expected shortfall (SES), the systemic risk measure (SRISK), or the delta conditional value-at-risk ([Formula: see text]CoVaR). We study their asymptotic properties in the presence of estimation risk and investigate their finite sample performance via Monte Carlo simulations. An empirical application to a panel of U.S. financial institutions is conducted to assess the validity of MES, SRISK, and [Formula: see text]CoVaR forecasts issued from a bivariate GARCH model with a dynamic conditional correlation structure. Our results show that this model provides valid forecasts for MES and SRISK when considering a medium-term horizon. Finally, we propose an early warning system indicator for future systemic crises deduced from these backtests. Our indicator quantifies how much is the measurement error issued by a systemic risk forecast at a given point in time which can serve for the early detection of global market reversals. This paper was accepted by Kay Giesecke, finance.

We propose an estimation methodology tailored for large unbalanced panels of individual stock returns to study the factor structure and expected returns in international stock markets. We show that the local market is necessary to capture the factor structure in both developed and emerging markets. Neither the presence of multiple world or regional risk factors, systematic currency risk factors, nor a country-specific currency subsumes the importance of the local market factor. All factors, including the local market, carry significant risk premia across a large proportion of countries. The contribution of pricing errors to total expected returns is large and time-varying.

Although they provide an important link between deep subduction and mid-crustal processes in the Saxothuringian Domain (Bohemian Massif), the medium to low-grade metasediments surrounding the well-documented (U)HP rocks of the Erzgebirge crystalline complex are scarcely studied. To constrain the Variscan evolution, the transition from the low-grade phyllites to the footwall medium-grade micaschists was investigated. Detailed geochronological (monazite U–Pb and mica 40Ar–39Ar dating), structural and petrological investigations, accompanied by thermodynamic modelling, were performed. We constrained the P–T conditions and timing of four deformation events (D1–D4) identified by structural analysis.The first M1-D1 event is characterized by HP–LT minerals (garnet, chloritoid, phengite, paragonite, and rutile) defining the S1 foliation. The calculated peak P–T conditions for M1 increase from 13 kbar and 520°C in phyllites to 25 kbar and 560°C in micaschists, suggesting a geothermal gradient of 6–11°C/km, typical for subduction environments. The M2-D2 event corresponds to the deformation and metamorphic overprint of the previous fabric during partial decompression. The M3-D3 event is mainly developed in micaschists and intensifies towards the footwall. It is accompanied by a subhorizontal S3 cleavage characterized by MP–MT assemblage bearing biotite, staurolite and ilmenite. The inferred peak P–T conditions for M3 are 5–9 kbar and 595°C representing a barrovian-type geothermal gradient from 17–30°C/km. Finally, all metamorphic fabrics were heterogeneously affected by the low-grade M4-D4 upright folding.Nine samples have been analyzed by in-situ monazite LASS ICP-MS geochronology. In phyllites, there is a prominent single group of ages around 350–340 Ma. In micaschists with intense M3 metamorphism, there are two groups of ages. The monazites located in the M3 matrix were dated at 330 Ma, while few grains in the garnet cores and within locally preserved M1 assemblages are older, around ~340 Ma. 40Ar–39Ar geochronology on micas was used to date 16 samples using step-heating and in-situ UV-laser ablation. The results are consistent with the monazite dating. The phyllites preserve ages spreading between 343–328 Ma, while in micaschists the ages cluster to ~330 Ma. The geochronological data revealed that at least part of the phyllites experienced burial and exhumation between 350–340 Ma, while the burial phase of micaschists is slightly younger (340–335 Ma). The strong M3 metamorphic overprint is restricted to micaschists and is dated around 330 Ma and interpreted as the exhumation, ductile thinning and final cooling of the wedge.The D1-D2 events (350–335 Ma) are interpreted to record the growth and evolution of the Saxothuringian orogenic wedge while its present-day architecture resulted from significant vertical shortening D3 associated with barrovian type metamorphism M3 (330 Ma) and ductile thinning. Altogether, a new tectonic model is proposed, in which the Erzgebirge part of the Saxothuringian Domain reveals a spectacular example of active margin evolution from the formation of accretionary prism to the building of the orogenic wedge by accretion of subducted continental crust and finally its extensional collapse.

Recently, inter-est in the isosteric replacement of a nitro-gen atom to selenium, sulfur or oxygen atoms has been highlighted in the design of potential inhibitors for cancer research. In this context, the structures of 5-(1

Widespread overprinting of early high-pressure/low-temperature (HP/LT) subduction stages due to subsequent collisional or late-orogenic tectono-metamorphic events is a common feature affecting the interpretation of geochronologic data from HP/LT orogens. The Betic-Rif orogen is exemplary in this connection as a great majority of published radiometric ages are found to cluster around 20 Ma. This clustering is commonly interpreted as reflecting a short, yet complex, succession of tectono-metamorphic events spanning only over a few Myr, including back-arc extension and overthrusting of the Internal Zones on the External Zones. An alternative explanation consists in the poor preservation of a much earlier HP/LT metamorphic event, presumably Eocene, coeval with subduction and crustal thickening in the Internal Zones, and particularly the Alpujárride Complex. However, this age is vividly debated due to widespread resetting by the Early Miocene HT/LP overprint. In this study, we provide new Ar/Ar evidence from white micas selected along an E-W section of the Internal Betics, from the central to the eastern Alpujárride Complex. Our new data show (a) that exceptionally well-preserved HP/LT parageneses in this unit retain a well-defined Eocene age around 38 Ma, and (b) that widespread 20 Ma ages recorded all along the section correspond to a regional stage of exhumation, coeval with a major change in the kinematics of back-arc extension. Our study provides conclusive evidence that Ar/Ar dating of carefully targeted HP/LT associations can overcome the problem of extensive late-orogenic overprinting, testifying for an Eocene HP event around 38 Ma in the Betic-Rif orogen., CAMPARIS; ISTeP; Institut des Sciences de la Terre d’Orléans; Région Centre; Yann Rolland; European Research Council 290864; Labex ANR‐10‐LABX‐100‐01, ANR‐11‐EQPX‐0036; Centre National de la Recherche Scientifique; Bureau de Recherches Géologiques et Minières; Total CGL2015‐67130‐ C2‐1‐R; Sorbonne Université

This paper studies new tests for the number of latent factors in a large cross-sectional factor model with small time dimension. These tests are based on the eigenvalues of variance-covariance matrices of (possibly weighted) asset returns, and rely on either the assumption of spherical errors, or instrumental variables for factor betas. We establish the asymptotic distributional results using expansion theorems based on perturbation theory for symmetric matrices. Our framework accommodates semi-strong factors in the systematic components. We propose a novel statistical test for weak factors against strong or semi-strong factors. We provide an empirical application to US equity data. Evidence for a different number of latent factors according to market downturns and market upturns, is statistically ambiguous in the considered subperiods. In particular, our results contradicts the common wisdom of a single factor model in bear markets.

We develop a penalized two-pass regression with time-varying factor loadings. The penalization in the first pass enforces sparsity for the time-variation drivers while also maintaining compatibility with the no-arbitrage restrictions by regularizing appropriate groups of coefficients. The second pass delivers risk premia estimates to predict equity excess returns. Our Monte Carlo results and our empirical results on a large cross-sectional data set of US individual stocks show that penalization without grouping can yield to nearly all estimated time-varying models violating the no-arbitrage restrictions. Moreover, our results demonstrate that the proposed method reduces the prediction errors compared to a penalized approach without appropriate grouping or a time-invariant factor model.

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. Ministry of Education (MOE) National Research Foundation (NRF) Published version JA and BS acknowledge support from both LabEx VOLTAIRE (ANR-10-LABX-100-01) and EquipEx PLANEX (ANR-11-EQPX0036) projects. SU acknowledges funding from the Stephen Riady Geosciences Scholarship 2018–2019. FC acknowledges support by the Earth Observatory of Singapore via its funding from the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centres of Excellence initiative. FC was funded by NRFi Award (NRFNRFI2017-06). This work comprises EOS contribution number 455. SC acknowledges funding from the NASA Interdisciplinary Research in Earth Science program (80NSSC20K1773).

Since May 2018 till the end of 2021, Mayotte island has been the locus of a major submarine volcanic eruption characterized by the offshore emission of more than 6.5 km of basanitic magma. The eruption occurred along a WNW–ESE trending submarine ridge on the east flank of the island where, in addition, several seemingly recent phonolitic bodies were also identified close to the island. To define realistic scenarios of magma ascent and potentially predict the style of an upcoming event, it is crucial to have a precise understanding on the plumbing system operating below volcanoes. The putative relationships between basanites emitted by the new volcano and these recent phonolites have been experimentally explored by performing crystallization experiments on a representative basanite over a large range of pressures (up to 400 MPa). The results show that the crystallization of basanite at crustal levels (12–15 km) yields a phonolitic residual liquid containing up to 3–4 wt% after 65 wt% of an assemblage of olivineplagioclaseamphiboleclinopyroxenebiotitemagnetiteilmeniteapatite. The final iron content of the residual phonolitic liquids is strongly controlled by the depth/pressure of fractionation. Fe-rich phonolites from the submarine ridge are produced at 6–8 km depth, while a shallower differentiation (4–5 km) results in the production of liquids with trachyte–benmoreite affinities. If the fractionation process occurs at depths higher than 8 km, the resulting phonolitic melts are progressively enriched in – but depleted in FeO*, ie unlike those erupted. We therefore conclude that phonolitic magma production and storage at Mayotte is a rather shallow process., Depuis mai 2018 et jusqu’à la fin de l’année 2021, l’île de Mayotte a été le scenario d’une éruption volcanique sous-marine majeure caractérisée par l’émission en mer de plus de 6,5 km de magma basanitique. L’éruption s’est produite le long d’une ride sous-marine orientée ONO–ESE sur le flanc est de l’île où, entre autre, plusieurs corps phonolitiques d’ aspect récent ont également été identifiés à proximité de l’île. Pour définir des scénarios réalistes d’ascension du magma et potentiellement prévoir le style d’un événement à venir, il est crucial d’avoir une compréhension précise du système de plomberie magmatique opérant sous les volcans. Les relations génétiques potentielles entre les basanites émises par le nouveau volcan et ces phonolites récentes ont été explorées expérimentalement en effectuant des expériences de cristallisation sur une basanite représentative, et ce sur une large gamme de pressions (jusqu’à 400 MPa). Les résultats montrent que la cristallisation de la basanite à des profondeurs crustales (12–15 km) produit un liquide résiduel phonolitique contenant jusqu’à 3–4 % en poids (pd.%) de HO, après la précipitation d’au moins 65 pd.% d’un assemblage d’olivineplagioclaseamphiboleclinopyroxènebiotitemagnétiteilméniteapatite. La teneur finale en fer des liquides phonolitiques résiduels est fortement contrôlée par la profondeur/pression de cristallisation. Les phonolites riches en fer de la dorsale sous-marine sont produites à 6–8 km de profondeur, tandis qu’une différenciation moins profonde (4–5 km) entraîne la production de liquides à affinités trachyte–benmoreite. Si le processus de fractionnement se produit à des profondeurs supérieures à 8 km, les liquides phonolitiques résultants sont progressivement enrichis en SiO–AlO mais appauvris en FeO*, c’est-à-dire différents des phonolites naturelles. Nous concluons donc que la production et le stockage de magma phonolitique à Mayotte est un processus plutôt superficiel.

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.

International audience; Pantelleria volcano has a particularly intriguing evolutionary history intimately related to the peralkaline composition of its explosively erupted magmas. Due to the stratigraphic complexity, studies over the last two decades have explored either only the pre-Green Tuff ignimbrite volcanism or the post-Green Tuff activity. We here focus on the whole evolutionary history, detailing the achievements since the first pioneering studies, in order to illustrate how the adoption and integration of progressively more accurate methods (40 Ar/ 39 Ar, paleomagnetism, petrography, and detailed field study) have provided many important independent answers to unresolved questions. We also discuss rheomorphism, a distinct feature at Pantelleria, at various scales and possible evidence for multiple, now hidden, caldera collapses. Although the evolutionary history of Pantelleria has shown that each ignimbrite event was followed by a period of less intense explosivity (as could be the present-day case), new geochronological and geochemical data may indicate a long-term waning of volcanic activity.

International audience; Nitrogen, carbon, hydrogen and sulfur are essential elements for life constituting less than ca. 1 % of terrestrial planet masses. While they are abundant in the atmosphere due to their volatile nature, the Earth’s interior represents the major C-H-N-S reservoirs. Capturing the origin of such distribution between surficial and deep reservoirs require deciphering 4.5 Giga-years of planetary activities, with many unknowns. Here, we show that the mass of carbon, nitrogen and presumably hydrogen outgassed by the last magma ocean episode, 4.5 Giga-years ago, is similar to the mass of these elements in Earth’s present-day exosphere (atmosphere+ocean+crust). By modelling the equilibrium partitioning of C-H-O-N-S elements between the magma ocean and its atmosphere, we show that the oxidation state is critical, yielding H2-CO dominated atmospheres under strongly reduced conditions and CO2-N2-SO2-rich ones under oxidizing conditions. On Earth, magma ocean degassing at reducing conditions must have produced a C-N-H rich atmosphere. Venus’s dry, SO2-poor, CO2-N2 atmosphere perfectly corresponds to an equilibration under slightly more oxidized conditions, possibly linked to enhanced hydrogen loss to space due to a long-lasting magma ocean stage9 . The C-H-N contents of the mantle and the atmosphere must have marginally changed since these reservoirs were born, pushing back the setting of habitability to the very first 100 millions of years of planetary systems.

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.

This chapter surveys recent econometric methodologies for inference in large dimensional conditional factor models in finance. Changes in the business cycle and asset characteristics induce time variation in factor loadings and risk premia to be accounted for. The growing trend in the use of disaggregated data for individual securities motivates our focus on methodologies for a large number of assets. The chapter starts with a historical perspective on conditional factor models with a small number of assets for comparison purpose. Then, it outlines the concept of approximate factor structure in the presence of conditional information, and reviews an arbitrage pricing theory for large dimensional factor models in this framework. For inference, we distinguish between two different cases depending on whether factors are observable or not. We focus on diagnosing model specification, estimating conditional risk premia, and testing asset pricing restrictions under increasing cross-sectional and time series dimensions. At the end of the chapter, we provide new empirical findings based on a broad set of factor models and contrast analysis based on individual stocks and standard sets of portfolios. We also discuss the impact on computing time-varying cost of equity for a firm, and summarize differences between results for developed and emerging markets in an international setting.

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.

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 (...

We describe the first case of proximal ulnar pseudoaneurysm due to extended-spectrum beta-lactamase-producing Escherichia coli. We performed an open ligation of the ulnar artery and partial excision of the aneurysmal sac. This article discusses the etiology and surgical management of ulnar-infected pseudoaneurysms according to the literature data.

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

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.

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.

Inertial sensor calibration plays a progressively important role in many areas of research among which navigation engineering. By performing this task accurately, it is possible to significantly increase general navigation performance by correctly filtering out the deterministic and stochastic measurement errors that characterize such devices. While different techniques are available to model and remove the deterministic errors, there has been considerable research over the past years with respect to modelling the stochastic errors which have complex structures. In order to do the latter, different replicates of these error signals are collected and a model is identified and estimated based on one of these replicates. While this procedure has allowed to improve navigation performance, it has not yet taken advantage of the information coming from all the other replicates collected on the same sensor. However, it has been observed that there is often a change of error behaviour between replicates which can also be explained by different (constant) external conditions under which each replicate was taken. Whatever the reason for the difference between replicates, it appears that the model structure remains the same between replicates but the parameter values vary. In this work we therefore consider and study the properties of different approaches that allow to combine the information from all replicates considering this phenomenon, confirming their validity both in simulation settings and also when applied to real inertial sensor error signals. By taking into account parameter variation between replicates, this work highlights how these approaches can improve the average navigation precision as well as obtain reliable estimates of the uncertainty of the navigation solution.

Inertial sensor calibration plays a progressively important role in many areas of research among which navigation engineering. By performing this task accurately, it is possible to significantly increase general navigation performance by correctly filtering out the deterministic and stochastic measurement errors that characterize such devices. While different techniques are available to model and remove the deterministic errors, there has been considerable research over the past years with respect to modelling the stochastic errors which have complex structures. In order to do the latter, different replicates of these error signals are collected and a model is identified and estimated based on one of these replicates. While this procedure has allowed to improve navigation performance, it has not yet taken advantage of the information coming from all the other replicates collected on the same sensor. However, it has been observed that there is often a change of error behaviour between replicates which can also be explained by different (constant) external conditions under which each replicate was taken. Whatever the reason for the difference between replicates, it appears that the model structure remains the same between replicates but the parameter values vary. In this work we therefore consider and study the properties of different approaches that allow to combine the information from all replicates considering this phenomenon, confirming their validity both in simulation settings and also when applied to real inertial sensor error signals. By taking into account parameter variation between replicates, this work highlights how these approaches can improve the average navigation precision as well as obtain reliable estimates of the uncertainty of the navigation solution.