Morphotectonics of the central Muertos thrust belt and Muertos Trough (northeastern Caribbean)

Multibeam bathymetry data acquired during the 2005 Spanish R/V Hespérides cruise and reprocessed multichannel seismic profiles provide the basis for the analysis of the morphology and deformation in the central Muertos Trough and Muertos thrust belt. The Muertos Trough is an elongated basin developed where the Venezuelan Basin crust is thrusted under the Muertos fold-and-thrust belt. Structural variations along the Muertos Trough are suggested to be a consequence of the overburden of the asymmetrical thrust belt and by the variable nature of the Venezuelan Basin crust along the margin. The insular slope can be divided into three east–west trending slope provinces with high lateral variability which correspond to different accretion stages: 1) The lower slope is composed of an active sequence of imbricate thrust slices and closed fold axes, which form short and narrow accretionary ridges and elongated slope basins; 2) The middle slope shows a less active imbricate structure resulting in lower superficial deformation and bigger slope basins; 3) The upper slope comprises the talus region and extended terraces burying an island arc basement and an inactive imbricate structure. The talus region is characterized by a dense drainage network that transports turbidite flows from the islands and their surrounding carbonate platform areas to the slope basins and sometimes to the trough. In the survey area the accommodation of the ongoing east–west differential motion between the Hispaniola and the Puerto Rico–Virgin Islands blocks takes place by means of diffuse deformation. The asymmetrical development of the thrust belt is not related to the geological conditions in the foreland, but rather may be caused by variations in the geometry and movement of the backstop. The map-view curves of the thrust belt and the symmetry of the recesses suggest a main north–south convergence along the Muertos margin. The western end of the Investigator Fault Zone comprises a broad band of active normal faults which result in high instability of the upper insular slope

Thermodynamic evidence of giant salt deposit formation by serpentinization: an alternative mechanism to solar evaporation

International audienceThe evaporation of seawater in arid climates is currently the main accepted driving mechanism for the formation of ancient and recent salt deposits in shallow basins. However, the deposition of huge amounts of marine salts, including the formation of tens of metres of highly soluble types (tachyhydrite and bischofite) during the Aptian in the South Atlantic and during the Messinian Salinity Crisis, are inconsistent with the wet and warm palaeoclimate conditions reconstructed for these periods. Recently, a debate has been developed that opposes the classic model of evaporite deposition and argues for the generation of salt by serpentinization. The products of the latter process can be called "dehydratites". The associated geochemical processes involve the consumption of massive amounts of pure water, leading to the production of concentrated brines. Here, we investigate thermodynamic calculations that account for high salinities and the production of soluble salts and MgCl2-rich brines through sub-seafloor serpentinization processes. Our results indicate that salt and brine formation occurs during serpentinization and that the brine composition and salt assemblages are dependent on the temperature and CO2 partial pressure. Our findings help explain the presence and sustainability of highly soluble salts that appear inconsistent with reconstructed climatic conditions and demonstrate that the presence of highly soluble salts probably has implications for global tectonics and palaeoclimate reconstructions

Evolution of a low convergence collisional orogen: a review of Pyrenean orogenesis

The Pyrenees is a collisional orogen built by inversion of an immature rift system during convergence of the Iberian and European plates from Late Cretaceous to late Cenozoic. The full mountain belt consists of the pro-foreland southern Pyrenees and the retro-foreland northern Pyrenees, where the inverted lower Cretaceous rift system is mainly preserved. Due to low overall convergence and absence of oceanic subduction, this orogen preserves one of the best geological records of early orogenesis, the transition from early convergence to main collision and the transition from collision to post-convergence. During these transitional periods major changes in orogen behavior reflect evolving lithospheric processes and tectonic drivers. Contributions by the OROGEN project have shed new light on these critical periods, on the evolution of the orogen as a whole, and in particular on the early convergence stage. By integrating results of OROGEN with those of other recent collaborative projects in the Pyrenean domain (e.g., PYRAMID, PYROPE, RGF-Pyrénées), this paper offers a synthesis of current knowledge and debate on the evolution of this immature orogen as recorded in the synorogenic basins and fold and thrust belts of both the upper European and lower Iberian plates. Expanding insight on the role of salt tectonics at local to regional scales is summarised and discussed. Uncertainties involved in data compilation across a whole orogen using different datasets are discussed, for example for deriving shortening values and distribution

Remote sensing using hyperspectral imaging for the mapping of the atmospheric aerosol particle emissions.

La dégradation de la qualité de l’air en raison de l’émission de particules fines dans l’atmosphère (encore nommées aérosols) est un problème environnemental et sanitaire majeur. Les sources d’émission d’aérosols sont nombreuses et diversifiées (trafic routier, industrie, chauffage, ...) et les mécanismes de dispersion et de modification physico-chimique de ces particules restent complexes à représenter dans les modèles de prévision de la qualité de l’air. L’évolution spatio-temporelle des émissions de panaches industriels reste encore mal appréhendée, mais sa connaissance demeure primordiale pour le suivi de la qualité de l'air dans le voisinage des sources. La collecte d’observations est donc essentielle pour améliorer nos connaissances sur ces émissions et de leurs impacts. Les mesures in-situ n'offrent toutefois pas une spatialisation géographique adéquate autour des sites d’émission. Plusieurs travaux menés en partie par l’ONERA ont permis de montrer la sensibilité l’imagerie hyperspectrale aéroportée dans le domaine réflectif (0.4-2.5 µm) pour la caractérisation des propriétés des particules émises par la source. L’utilisation de ces produits satellites pourrait permettre de compléter les données déjà existantes pour le suivi d’émissions d’aérosols.L’objectif de cette thèse est alors d'évaluer la sensibilité de l’imagerie hyperspectral satellitaire pour la détection et la caractérisation des propriétés physico-chimique des aérosols industriels nécessaire à la réalisation d'un bilan de masse pour les fines particules.Cela nécessite d’être capable de modéliser les interactions entre les aérosols d'un panache avec le flux solaire. De plus, une connaissance de l’information spectrale des sols en dessous du panache est nécessaire pour modéliser le signal des aérosols du panache. Ce signal ou réflectance de surface est modélisé par une méthode de fusion s’appuyant sur l’utilisation d’une donnée exogène provenant généralement d’une donnée multispectrale dont le temps de revisite est de quelques jours.Une caractérisation des propriétés des aérosols est ensuite réalisée par l’intermédiaire d’un algorithme d’optimisation utilisant le formalisme Bayésien. Cela permet de restituer conjointement des paramètres dont les signatures spectrales peuvent être partiellement similaires et d’analyser les incertitudes statistiques associées aux restitutions. Ensuite, un bilan de masse, puis une estimation du flux et de son incertitude est réalisé.Pour mener à bien cette étude, une première application de ce processus d’inversion a été réalisée sur une image hyperspectrale aéroportée d'un site sidérurgique, puis une seconde sur des images PRISMA sur différents sites industriels : une centrale à charbon, un site d’exploitation pétrolière et un site sidérurgique.Les images satellitaires PRISMA ont une résolution spatiale de 30 m et une résolution spectrale de 10 nm.Une telle approche a permis de montrer la sensibilité de la donnée hyperspectrale satellite à différents types d’aérosols tout en adaptant notre modélisation aux différentes géométries d’émissions rencontrées.Enfin, cela nous a permis de restituer des débits de particules pour le mode d'accumulation variant entre 131 et 394 g.s-1 pour des rayons médians moyens variant entre 0.10 et 0.12 µm pour les sites étudiés à partir des données PRISMA.The air quality degradation due to the fine particle emissions in the atmosphere (also called aerosols) is a major environmental and health problem. There are multiple and diversified sources of aerosol emissions (road traffic, industry, heating, ...) and the dispersion mechanisms and physico-chemical modification of these particles remain complex to represent in air quality forecasting models. The spatio-temporal evolution of industrial plume emissions is not well understood, but its knowledge remains essential for air quality monitoring in the vicinity of the sources. The collection of observations is essential to improve our knowledge of the emission and their impacts. In-situ measurements do not offer an adequate geographical spatialization around the mission sites. Several works carried out by ONERA have shown the sensitivity of airborne hyperspectral imaging in the reflective domain (0.4-2.5 µm) for the characterization of the particle properties emitted by the source. The use of these satellite products could thus allow to complete the already existing data for the monitoring of aerosol emissions.The objective of this thesis is to evaluate the sensitivity of hyperspectral satellite imagery for the detection and characterization of the physicochemical properties of industrial aerosols.This requires first the ability to model the interactions between industrial aerosols emitted into the atmosphere with the upward and downward solar flux, by taking into account the scene acquisition properties and the chemical composition of the atmosphere. In addition, knowledge of the spectral information of the soils below the plume is required to model the plume aerosol signal. This signal, also called surface reflectance, is modeled by a fusion method based on the use of an exogenous data generally coming from a multi-spectral data whose revisit time is a few days.A characterization of aerosol properties is performed after through an optimization algorithm using a Bayesian formalism. This allows first to jointly retrieve parameters whose spectral signatures can be partially similar and next to analyze the statistical uncertainties associated with the obtained restitutions. From these restitutions, a mass balance, then an estimation of the flux and its uncertainties is performed.To carry out this study, a first application of this inversion process was carried out on an airborne hyperspectral image of a sinter plant and a second one was carried out on different industrial sites: a coal-fired power plant, an oil exploitation site and a steel site. The PRISMA satellite images have a spatial resolution of 30 m and a spectral resolution of 10 nm. Such an approach allowed us to show the sensitivity of hyperspectral imagery to different types of aerosols while adapting our modeling to the different emission geometries encountered. Finally, this allowed us to retrieve particle flow rates for the accumulation mode varying between 131 and 394 g.s-1 for mean median radii varying between 0.10 and 0.12 µm for the sites studied from the PRISMA data

Industrial Plume Properties Retrieved by Optimal Estimation Using Combined Hyperspectral and Sentinel-2 Data

Stack emissions from the industrial sector are a subject of concern for air quality. However, the characterization of the stack emission plume properties from in situ observations remains a challenging task. This paper focuses on the characterization of the aerosol properties of a steel plant stack plume through the use of hyperspectral (HS) airborne remote sensing imagery. We propose a new method, based on the combination of HS airborne acquisition and surface reflectance imagery derived from the Sentinel-2 Multi-Spectral Instrument (MSI). The proposed method detects the plume footprint and estimates the surface reflectance under the plume, the aerosol optical thickness (AOT), and the modal radius of the plume. Hyperspectral surface reflectances are estimated using the coupled non-negative matrix factorization (CNMF) method combining HS and MSI data. The CNMF reduces the error associated with estimating the surface reflectance below the plume, particularly for heterogeneous classes. The AOT and modal radius are retrieved using an optimal estimation method (OEM), based on the forward model and allowing for uncertainties in the observations and in the model parameters. The a priori state vector is provided by a sequential method using the root mean square error (RMSE) metric, which outperforms the previously used cluster tuned matched filter (CTMF). The OEM degrees of freedom are then analysed, in order to refine the mask plume and to enhance the quality of the retrieval. The retrieved mean radii of aerosol particles in the plume is 0.125 μμm, with an uncertainty of 0.05 μμm. These results are close to the ultra-fine mode (modal radius around 0.1 μμm) observed from in situ measurements within metallurgical plant plumes from previous studies. The retrieved AOT values vary between 0.07 (near the source point) and 0.01, with uncertainties of 0.005 for the darkest surfaces and above 0.010 for the brightest surfaces

Télédétection par imagerie hyperspectrale pour la cartographie des émissions de particules d’aérosols dans l’atmosphère

The air quality degradation due to the fine particle emissions in the atmosphere (also called aerosols) is a major environmental and health problem. There are multiple and diversified sources of aerosol emissions (road traffic, industry, heating, ...) and the dispersion mechanisms and physico-chemical modification of these particles remain complex to represent in air quality forecasting models. The spatio-temporal evolution of industrial plume emissions is not well understood, but its knowledge remains essential for air quality monitoring in the vicinity of the sources. The collection of observations is essential to improve our knowledge of the emission and their impacts. In-situ measurements do not offer an adequate geographical spatialization around the mission sites. Several works carried out by ONERA have shown the sensitivity of airborne hyperspectral imaging in the reflective domain (0.4-2.5 µm) for the characterization of the particle properties emitted by the source. The use of these satellite products could thus allow to complete the already existing data for the monitoring of aerosol emissions. The objective of this thesis is to evaluate the sensitivity of hyperspectral satellite imagery for the detection and characterization of the physicochemical properties of industrial aerosols. This requires first the ability to model the interactions between industrial aerosols emitted into the atmosphere with the upward and downward solar flux, by taking into account the scene acquisition properties and the chemical composition of the atmosphere. In addition, knowledge of the spectral information of the soils below the plume is required to model the plume aerosol signal. This signal, also called surface reflectance, is modeled by a fusion method based on the use of an exogenous data generally coming from a multi-spectral data whose revisit time is a few days. A characterization of aerosol properties is performed after through an optimization algorithm using a Bayesian formalism. This allows first to jointly retrieve parameters whose spectral signatures can be partially similar and next to analyze the statistical uncertainties associated with the obtained restitutions. From these restitutions, a mass balance, then an estimation of the flux and its uncertainties is performed. To carry out this study, a first application of this inversion process was carried out on an airborne hyperspectral image of a sinter plant and a second one was carried out on different industrial sites: a coal-fired power plant, an oil exploitation site and a steel site. The PRISMA satellite images have a spatial resolution of 30 m and a spectral resolution of 10 nm. Such an approach allowed us to show the sensitivity of hyperspectral imagery to different types of aerosols while adapting our modeling to the different emission geometries encountered. Finally, this allowed us to retrieve particle flow rates for the accumulation mode varying between 131 and 394 g.s-1 for mean median radii varying between 0.10 and 0.12 µm for the sites studied from the PRISMA data.La dégradation de la qualité de l’air en raison de l’émission de particules fines dans l’atmosphère (encore nommées aérosols) est un problème environnemental et sanitaire majeur. Les sources d’émission d’aérosols sont nombreuses et diversifiées (trafic routier, industrie, chauffage, ...) et les mécanismes de dispersion et de modification physico-chimique de ces particules restent complexes à représenter dans les modèles de prévision de la qualité de l’air. L’évolution spatio-temporelle des émissions de panaches industriels reste encore mal appréhendée, mais sa connaissance demeure primordiale pour le suivi de la qualité de l'air dans le voisinage des sources. La collecte d’observations est donc essentielle pour améliorer nos connaissances sur ces émissions et de leurs impacts. Les mesures in-situ n'offrent toutefois pas une spatialisation géographique adéquate autour des sites d’émission. Plusieurs travaux menés en partie par l’ONERA ont permis de montrer la sensibilité l’imagerie hyperspectrale aéroportée dans le domaine réflectif (0.4-2.5 µm) pour la caractérisation des propriétés des particules émises par la source. L’utilisation de ces produits satellites pourrait permettre de compléter les données déjà existantes pour le suivi d’émissions d’aérosols.L’objectif de cette thèse est alors d'évaluer la sensibilité de l’imagerie hyperspectral satellitaire pour la détection et la caractérisation des propriétés physico-chimique des aérosols industriels nécessaire à la réalisation d'un bilan de masse pour les fines particules.Cela nécessite d’être capable de modéliser les interactions entre les aérosols d'un panache avec le flux solaire. De plus, une connaissance de l’information spectrale des sols en dessous du panache est nécessaire pour modéliser le signal des aérosols du panache. Ce signal ou réflectance de surface est modélisé par une méthode de fusion s’appuyant sur l’utilisation d’une donnée exogène provenant généralement d’une donnée multispectrale dont le temps de revisite est de quelques jours.Une caractérisation des propriétés des aérosols est ensuite réalisée par l’intermédiaire d’un algorithme d’optimisation utilisant le formalisme Bayésien. Cela permet de restituer conjointement des paramètres dont les signatures spectrales peuvent être partiellement similaires et d’analyser les incertitudes statistiques associées aux restitutions. Ensuite, un bilan de masse, puis une estimation du flux et de son incertitude est réalisé.Pour mener à bien cette étude, une première application de ce processus d’inversion a été réalisée sur une image hyperspectrale aéroportée d'un site sidérurgique, puis une seconde sur des images PRISMA sur différents sites industriels : une centrale à charbon, un site d’exploitation pétrolière et un site sidérurgique.Les images satellitaires PRISMA ont une résolution spatiale de 30 m et une résolution spectrale de 10 nm.Une telle approche a permis de montrer la sensibilité de la donnée hyperspectrale satellite à différents types d’aérosols tout en adaptant notre modélisation aux différentes géométries d’émissions rencontrées.Enfin, cela nous a permis de restituer des débits de particules pour le mode d'accumulation variant entre 131 et 394 g.s-1 pour des rayons médians moyens variant entre 0.10 et 0.12 µm pour les sites étudiés à partir des données PRISMA

Géodynamique andine : résumés étendus = Andean geodynamics : extended abstracts

Le système de failles de Guadalupe-Mina de Coro-Chuchure s'étend sur une soixantaine de kilomètres en direction ENE-WSW au nord de l'état de Falcon (Venezuela nord-occidental). La trace de ce système présente deux virgations qui décalent le front de quelques kilomètres. Nous avons modélisé analogiquement la plus orientale des deux virgations au moyen de modèles en sable. Cette virgation s'avère être une zone de transfert dûe à la présence d'un rejet au niveau du socle, introduit par la faille normale de Los Médanos. (Résumé d'auteur

Analogical Model of the Deformation of Sandy Submarine Channels in Shaly Pelagic Sediments

The grassemargins are affected by strong deformation due to the increase of the sedimentary cover, the eventual basement tilt and the resulting gravity gliding. These movements affect the entire sedimentary sequence including the sandy channels often present in the shaly or silty pile. As a result, the channel shape changes with time, faults may appear that will break the sand continuity and therefore affect the petroleum reservoir quality of these channels. In this paper we document the brittle deformation of a channel through analogical models. The channel is embedded in ductile series where gravity sliding induces multi-directional extension. Results show that the channel is progressively deformed and cut by faults. These ones are systematically perpendicular to the channel borders, do not affect the meanders and are poorly dependent on the regional dip

Thermal record of hyperextended rifted margins: the fossil record of the Pyrenees

&amp;lt;p&amp;gt;The thermal architecture of late rifting to breakup along the deep passive margins is still poorly known. This is mostly because of the limited access to industry drillhole data that, anyway, calibrate topographic highs and rarely the deepest rift domains (and even less the basement). However, unravelling this evolution is a fundamental requirement to define the ultimate exploration potential of these frontier domains. An alternative way to document this thermal evolution is to describe fossil analogues onshore. In this study, we use the fossil hyperextension record of the Pyrenean belt that was sampled by orogenic deformation into the North Pyrenean None and Nappe des Marbres alpine units. Previous studies have shown that the rift came into hyperextension and recorded locally mantle exhumation. These rift domains are associated with a HT-LP metamorphism event that was shown to vary spatially within the rift basin as well as into the basement. In order to restore the late rift thermal architecture of the Pyrenean hyperextended rift, we use a new compilation of Raman Spectroscopy measurements on Carbonaceous Material (RSCM) and Vitrinite Reflectance data. This method allows to record the palaeo-maximum temperatures in the sedimentary basins spatially as well as vertically and can be superposed to geological sections. This method was applied in almost 200 samples collected all along the belt at different stratigraphic level as well as into the Paleozoic basement. When the base of the rift basin is exposed, RSCM Tmax range between 450 and 620&amp;amp;#176;C below a &amp;lt;5km thick sedimentary pile. Western Pyrenees was shown to be an exception as RSCM Tmax are less than 300&amp;amp;#176;C on the outcropping superficial part of the rift basin. However; Vitrinite Reflectance data from wells that are calibrating the deep basin demonstrate that the same thermal intensity was actually reached. These results discard any lateral variation in thermal regime and is pointing out that it is a burial function into a (very)high late rift thermal gradient that largely exceed 100&amp;amp;#176;c/km. Far from being restricted to the Pyrenean case, such a thermal evolution with the same amplitude gradient within the same exhumed mantle domains were documented in the Northern Red Sea example.&amp;lt;/p&amp;gt; </jats:p