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Structural control of the hydrothermal system of the North-East Pyrénées (Corbières): Geothermal implications
No full text(IF 2.1; Q1)International audienceWe investigate the hydrothermal system located at the North of the Pyrenean front forming a low relief area in a sedimentary environment (from the Mouthoumet Massif to the Montagne d'Alaric, Eastern-Pyr & eacute;n & eacute;es). This region is structured by W-E oriented Pyrenean folds and thrusts, which are affected by a dense network of NE-SW oriented fault system along which 24 hydrothermal springs localizes (>15 degrees C). Thanks to the construction of three balanced cross-sections and field-work campaigns, we infer that the structures abovementioned govern the hydrothermal system for the following reasons: 1) the Devonian carbonate layer confined between phyllosilicate rich formations constitutes the main fractured and karstified reservoir, 2) Pyrenean folds allows the main reservoir to outcrop at anticlines reliefs, favouring water recharge, flow at depth and high water column within low dipping limbs and synclines, 3) the Oligo-Miocene normal faults cut the fold and thrust structures and the phyllosilicate rich layers, and form dilatant high dipping pathways favoring the overpressured hydrothermal fluids to outflow at topographic depressions. The relatively low topography of the recharge area suggest that spring temperature is mainly controlled by reservoir depth, and therefore the folded and thrusted structure of the Devonian unit. This understanding of the reservoir geology and hydrothermal system provides new knowledge useful for geothermal exploration in polyphased-tectonics sedimentary environment
Structure and evolution of the Gonave microplate at the northern boundary of the Caribbean plate
No full textInternational audienceAlong the northern strike-slip boundary of the Caribbean plate, strain is partitioned and accommodated by the relative motion of several microplates. Among these microplates, the Gonâve microplate is bounded by two major strike-slip fault systems: the Enriquillo Plantain Garden Fault Zone (EPGFZ) to the south and the Septentrional-Oriente Fault Zone (SOFZ) to the north, with the Cayman Trough and the Haitian Fold and Thrust belt defining its western and eastern limits, respectively. On 12 January 2010, a devastating Mw 7.0 earthquake struck along the EPGFZ, cross-cuts the southern peninsula of Haïti and the southern Gulf of Gonave. This earthquake, occurring on an uncharacterized fault segment, was both destructive and unexpected. Since then, geophysical and geological investigations have been performed to improve understanding of the fault geometries, kinematics and strain rates in the region. This study used multibeam bathymetry and reflection seismic data from various oceanographic campaigns in the Gulf of Gonave to highlight the spatial and temporal evolution of these structures. Data analysis revealed NE-SW trending tilted blocks belonging to the continental margin of the East Cayman Trough. Several of these blocks are bounded by low-angle normal faults, suggesting intense stretching. The various identified seismic horizons allow us to date the top of the syn-rift units in the Gulf of Gonave and confirm that rifting occurred between 49 and 56 Ma. Consequently, the eastern Cayman margin extends from northern Jamaica in the west to at least the eastern Gulf of Gonave, covering a typical continental margin distance of 450 km with a thinning rate of 2.7. Our study reveals that all extensional structures were later inverted by NE-SW-oriented compression, aligned with the trend of the tilted blocks in the Gulf of Gonâve. Shortening rates calculated from the Gulf of Gonave seismic profiles are compared with those obtained from onshore geological data and GPS block models. Notably, the shortening calculated in the Gulf of Gonave appears to be lower than the GPS-derived convergence rates of 6-7 mm/yr, suggesting a possible increase in deformation rates over time. Additionally, short-term deformation occurs on a reverse fault system in the southern Gulf of Gonâve. Based on the available data and the results of our study, we propose a novel model for the spatiotemporal evolution of tectonic structures extending from the northern Jamaican margin in the west to the Haitian fold-and-thrust belt in the east
Elusive tropical forest canopy diversity revealed through environmental DNA contained in rainwater
No full textVoir l'actualité INEE du 20 octobre 2025 : L’ADN environnemental, une solution innovante pour étudier la biodiversité des canopées tropicales : https://www.inee.cnrs.fr/fr/cnrsinfo/ladn-environnemental-une-solution-innovante-pour-etudier-la-biodiversite-des-canopeesInternational audienceExploring the biodiversity hidden in tropical rainforests canopies represents a major frontier in biodiversity research yet remains challenging. Environmental DNA (eDNA) can revolutionize this field as it did already in various ecosystems. Here, we test the hypothesis that eDNA contained in canopy throughfall could be used to monitor this elusive diversity and detect anthropogenic disturbance. Using custom-made, low-cost rain collectors, we sampled rainwash eDNA in a mature Amazonian forest and a nearby tree plantation. We successfully detected eDNA from tropical woody and epiphyte plants, vertebrates (mammals, birds, and amphibians), and insects (e.g., mosquitoes, ants, and beetles). The taxonomic composition and diversity reflected disturbance, with significantly lower diversity in the plantation. Crucially, rainwash eDNA integrated biodiversity over a 10-day period in passive collectors and provided a local signature. This approach has thus potential for establishing a cost-effective monitoring system for tropical moist forest canopies, applicable in impact assessments and sustainable management
La solidarité afro-diasporique : une question artistique et géopolitique
No full textInternational audienceConférence inscrite dans le cadre du programme "Traite négrière et postcolonialité", Université Félix Houphouët-Boigny (Côte d'Ivoire) - Master "Littérature et Civilisation des Amériques-Caraïbes
La biodiversité - urgence planète: Notre monde vivant en danger expliqué à tous
No full textInternational audienceSur Terre, nous sommes en colocation avec le reste du vivant. En malmenant la biodiversité, nous nous mettons nous-mêmes en péril. Ce livre explique pourquoi il est urgent de prendre soin de notre biodiversité et comment. 80 millions de tonnes de plastiques dans les océans, 7 milliards d’hectares de forêt asséchés par an, 30 % des batraciens en voie de disparition… L’effondrement de la biodiversité remet en cause les conditions de notre existence : notre sécurité alimentaire est menacée, notre approvisionnement en eau devient incertain, notre stabilité climatique vacille et notre santé se fragilise face aux maladies émergentes
Influence of mechanical stress on biomass allocation in three species (Pachira aquatica Aubl., Sextonia rubra (Mez) van der Werff and Simarouba amara Aubl.) with contrasting posture control mechanisms
No full textInternational audienceKey message: The posture control in Pachira aquatica, Sextonia rubra and Simarouba amara is achieved through contrasted mechanisms involving tensile stress in wood only, bark only or both. This study evidenced that the restoration of verticality does not imply an overall cost for trees but modifies growth kinetics and biomass allocation to organs and tissues, improving the posture control of the trees in the three species.Context: All trees need a motor system to correct their position through the generation of asymmetric tensile stress around the stem, leading to active bending. In angiosperms, depending on the species, tensile stress is generated either in wood (tension wood), in bark or in both.Aims: Here, we investigated how gravitropic stimuli (tilted stems without any movement) may affect growth and biomass allocation and whether this process depends on the posture control mechanism of the species.Methods: Tree growth kinetics, final biomass allocation and wood and bark proportion, localisation and density were measured on young tilted plants and straight plants as controls. Pachira aquatica, Sextonia rubra and Simarouba amara were selected according to the location of their their motor system within bark only, wood only or both wood and bark, respectively. Results: In response to tilting, trees from the three species increased their diameter and decreased their slenderness, but the total biomass (including stem and roots) was not different from that in the control trees, suggesting that reaction to artificial tilting does not imply a specific cost for the plant. However, the species exhibited strong differences in growth kinetics, in the amount and organisation of the tissues or in biomass allocation to different organs (root vs shoot, wood vs bark), adapted to the specificity of the posture control mechanisms and improving their motor function.Conclusion: Whatever the posture control mechanism, uprighting does not modify the total biomass invested. However, allocation of biomass to different organs is strongly modified to obtain an efficient control of the posture
L’exposition d’arts visuels Chemin de Guérison de Patricia Donatien : un discours écocritique sur l’impact de l’ère du plantationocène sur le corps martiniquais racisé
No full textReconstructing climate dynamics in the Cradle of Humankind, South Africa, using machine learning and mammalian fossil assemblages.
No full textInternational audienceFossil fauna recovered from palaeoanthropological sites can be used to reconstruct past climatic and environmental conditions when other traditional palaeoclimate proxies such as pollens, diatoms, lacustrine or marine sediments are not available. These reconstructions can help explore if climate-induced dynamics have shaped hominin diversification and influenced the development of new behaviors. Numerous palaeoenvironmental reconstruction methods have been developed over the years, and their application to the fossil faunas of the Cradle of Humankind (COH), South Africa, has produced diverse, sometimes contradictory results according to the methodology and fauna used. To investigate climate evolution over time within a unified methodological framework, we developed a novel palaeoclimatic reconstruction method based on random forest models, using the presence/absence data of rodents and bovids —two clades commonly employed in palaeoenvironmental reconstructions— as climate proxies. The application of artificial intelligence to the fossil record necessitates methodological adaptations to account for its inherent incompleteness and the absence of direct modern analogues for past faunal communities, which we discuss here. With this approach, we reconstructed evolution of temperatures and precipitation over the last 4 million years in the COH. Our reconstructions indicate relatively stable environmental conditions, closely resembling those of the present-day Sterkfontein Valley. We find no support for a shift from closed, humid, woodland-dominated environments to more open, arid, grassland-dominated landscapes over time, as is frequently proposed in the palaeoecological literature. Instead, the variability in reconstructed climatic conditions across different sites reflects fluctuations in faunal community composition, whose temporal resolution may limit direct correlations with long-term palaeoclimatic records from southern African marine archives
Agrégation anglais 2026 - Mark Twain. Adventures of Huckleberry Finn et le film de Wes Anderson, Moonrise Kingdom.
No full textInternational audienceCet ouvrage a été conçu pour préparer les candidats à la quatrième question du volet littéraire des épreuves écrites de la session 2026 de l’agrégation externe d’anglais. Celle-ci porte à la fois sur le roman de Mark Twain, Adventures of Huckleberry Finn (1884) et sur le film de Wes Anderson, Moonrise Kingdom (2012).La forme « hybride » littérature-cinéma se compose de deux œuvres différentes, et non d’une œuvre littéraire associée à son adaptation cinématographique, comme il en va habituellement de cette épreuve. Le défi interdisciplinaire, certes stimulant, prend cette année une tournure particulière. Outre les caractéristiques propres à chaque médium, nous avons cette fois-ci affaire à deux œuvres dont la « personnalité » artistique est bien établie, créées par deux auteurs dont le style est tout aussi distinct et marquant. La préparation au concours devra donc tenir compte de l’originalité de chaque œuvre tout en permettant un « dialogue » fructueux entre elles. C’est pourquoi les essais réunis dans cet ouvrage mettent en lumière la singularité de chaque œuvre, saisie dans sa dimension générique, contextuelle ou stylistique, en même temps que d’autres proposent des lectures croisées qui facilitent l’identification de nombreuses passerelles entre deux créations a priori exclusives l’une à l’autre, mais reliées de plusieurs manières
Variability of environmental, contextual and individual factors in human-shark interactions in New Caledonia, 1980–2022, with some comparisons to Reunion Island
No full textInternational audienceThis paper analyses data related to 62 human–shark interactions in New Caledonia and 60 in Reunion Island from 1980 to 2022. A database on human–shark interactions in New Caledonia and Reunion Island was developed using the same variables and similar time steps for both locations. The discussion focuses on human–shark interactions in New Caledonia, with some comparisons to those on Reunion Island where possible. Environmental, contextual and individual variables related to human–shark interactions were analysed to identify potential influencing factors. The data analysis for New Caledonia revealed some correlations between variables related to the human–shark interactions. The main results showed that there was a concomitant increase in human–shark interactions since 2010 in the bays of Noumea and in the prevalence of human–shark interactions among people practising boardsports since 2007. The year 2007 was a pivotal year with respect to differences in important parameters of human–shark interactions. The results of this comparison between Reunion Island and New Caledonia were as follows: fatal human–shark interactions occurred among individuals practising boardsports and in turbid environments, whereas nonfatal human–shark interactions among individuals engaged in spearfishing and in clear water in New Caledonia