Elaboration of the earthworm material collected on the Seychelles, Mauritius, Réunion, Mayotte and Sri Lanka islands resulted in recording 20 species altogether. Among them, the ocnerodrilid Maheina ...braueri (Michaelsen, 1897) endemic to Mahé (Seychelles) and the megascolecid Nellogaster bahli (Stephenson, 1925) endemic to Sri Lanka were reported for the first time since their original description. The material also contained some enigmatic juvenile specimens from Mayotte, most resembling the genus Diporochaeta
In July 2018, a large (ca. 6.55 km3), deep (ca. 2.5 to 3.3 km b.s.l) submarine eruption started ca. 50 km east of Mayotte Island. Samples of fresh basanitic lava rims were collected by dredging, at ...various times and locations from the newly formed Fani Maoré Edifice (FME). The logistical response to this extraordinary event also enabled the dredging of shallow (ca. 1.2 to 1.6 km below sea level, b.s.l.), fresh phonolitic lava and bomb rims in the so-called Horse-Shoe Area (HSA), ca. 15 km east of Mayotte. Better-known subaerial counterparts of Holocene age, have also been sampled in the La Vigie Maar (LVM) phonolitic deposits (Petite-Terre, Mayotte Island), for comparison with submarine samples. These samples belong to a single volcanic chain that extends from LVM to FME passing through HSA. A novel combination of Simultaneous Thermal Analysis (STA), which involves Differential Scanning Calorimetry (DSC), Thermal Gravimetry Analysis (TGA), and Evolved Gas Analysis conducted by Mass Spectrometry (EGA-MS), enable a reconstruction of the volatile distributions and compositions (H2O, CO2, and SO2) of these samples. Calorimetric and degassing profiles of controlled heating runs reveal different volatile reservoirs distributed as a function of sample textures and compositions, which have been further investigated by Scanning Electron Microscopy (SEM), Electron Probe Micro-Analysis (EPMA), and Raman spectroscopy. A linear correlation observed between the TGA and H2O-EGA-MS signal intensities also enables the quantification of adsorbed-external vs. dissolved-magmatic H2O contents of the studied samples. The novel application of this approach to volcanic products is thus confirmed as a reliable method to determine volatile characteristics in a wide range of samples, yielding a quantitative description of volatile behavior within the associated magmatic systems and eruptions.
•Mayotte volcanic chain is formed by submarine and subaerial alkaline volcanic products.•STA combined with EGA-MS technique allows the quantification of adsorbed vs. magmatic H2O.•Rock texture and composition control volatiles distribution and behavior.•Hydrostatic pressure delays magmatic H2O exsolution in the submarine products.•Magmatic CO2 exsolves at high magmatic pressures, forming CO2-rich bubbles and fluids.
A multichannel seismic reflection profile acquired during the SISMAORE cruise (2021) provides the first in-depth image of the submarine volcanic edifice, named Fani Maore, that formed 50 km east of ...Mayotte Island (Comoros Archipelago) in 2018–2019. This new edifice sits on a \({\sim }\)140 m thick sedimentary layer, which is above a major, volcanic layer up to \({\sim }\)1 km thick and extends over 120 km along the profile. This volcanic unit is made of several distinct seismic facies that indicate successive volcanic phases. We interpret this volcanic layer as witnessing the main phase of construction of the Mayotte Island volcanic edifice. A \({\sim }\)2.2–2.5 km thick sedimentary unit is present between this volcanic layer and the top of the crust. A complex magmatic feeder system is observed within this unit, composed of saucer-shape sills and seal bypass systems. The deepest tip of this volcanic layer lies below the top-Oligocene seismic horizon, indicating that the volcanism of Mayotte Island likely began around 26.5 Ma, earlier than previously assumed.
Objectif : Le département de Mayotte présente un retard important dans l’accès aux soins palliatifs. Nous présentons la démarche méthodologique d’évaluation des besoins en soins palliatifs de la ...population ayant conduit à faire une proposition d’offre de soins adaptée au contexte local (étude SP Mayotte). Méthode : Les grands principes d’une méthodologie de santé publique relative à l’évaluation des besoins de santé ont été suivis. Les chercheurs ont procédé à une analyse globale de la situation s’appuyant sur plusieurs axes : recherche bibliographique, recueil de données quantitatives, étude qualitative, entretiens avec experts locaux et décideurs institutionnels. Une restitution synthétique des résultats auprès des acteurs de terrain a été réalisée en clôture de l’étude, afin de soutenir les propositions de création d’une offre de soins palliatifs adaptée. Résultats : Devant la pauvreté des données épidémiologiques, l’étude qualitative a été déterminante pour évaluer les besoins. Les échanges avec les décideurs institutionnels ont permis d’approfondir la compréhension des spécificités locales et d’améliorer la relation entre les acteurs locaux, conduisant à l’émergence d’un processus de co-construction. En décembre 2019, une offre de soins palliatifs émanant des propositions de l’étude a été financée. Conclusion : Notre méthodologie s’est appuyée sur des échanges réguliers sur le terrain et a permis de favoriser l’émergence d’un élément déterminant pour la réussite du projet : l’adhésion des soignants et des décideurs institutionnels. Cette co-construction entre les partenaires a permis une interactivité entre les différentes catégories d’acteurs impliqués et a renforcé la qualité des travaux ainsi que l’émergence d’une intelligence collective.
Accurate and reliable bathymetric data are needed for a wide diversity of marine research and management applications. Satellite-derived bathymetry represents a time saving method to map large ...shallow waters of remote regions compared to the current costly in situ measurement techniques. This study aims to create very high-resolution (VHR) bathymetry and habitat mapping in Mayotte island waters (Indian Ocean) by fusing 0.5 m Pleiades-1 passive multispectral imagery and active ICESat-2 LiDAR bathymetry. ICESat-2 georeferenced photons were filtered to remove noise and corrected for water column refraction. The bathymetric point clouds were validated using the French naval hydrographic and oceanographic service Litto3D® dataset and then used to calibrate the multispectral image to produce a digital depth model (DDM). The latter enabled the creation of a digital albedo model used to classify benthic habitats. ICESat-2 provided bathymetry down to 15 m depth with a vertical accuracy of bathymetry estimates reaching 0.89 m. The benthic habitats map produced using the maximum likelihood supervised classification provided an overall accuracy of 96.62%. This study successfully produced a VHR DDM solely from satellite data. Digital models of higher accuracy were further discussed in the light of the recent and near-future launch of higher spectral and spatial resolution satellites.
The Mayotte seismic sequence that started on 10 May 2018, with a main shock of magnitude Mw 5.9 on May 15, followed by a major offshore volcanic activity, raises several questions of seismo-volcanic ...hazards in the Comoros region. The unexpected size and duration of the crisis is an opportunity to reassess the distribution and magnitude of the seismicity near Mayotte Island, but also regionally. We present a comprehensive seismicity catalogue of the region including the Mozambique Channel, the Mozambique coast and Madagascar, based partly on previously published data in the region and partly on unpublished data from local catalogues for the Comoros and Madagascar. Our catalogue extends from 1900 onward with a completeness of magnitude 5.5 until 1980s and decreasing only recently to 4.5 after 2010. It comprises the events of magnitude Mlv \({\ge }3.5\) for the seismic sequence of Mayotte from May 2018 to October 2020 as the crisis is still ongoing. Present knowledge of the seismicity, largely partial in distribution and magnitude before 1980, makes the seismic sequence of 2018–2020 an exceptional and unprecedented seismo-volcanic event in the region. We discuss the distribution of seismicity in time and space within the context of the south eastward propagation of the East African rift system towards Madagascar.
A major seismovolcanic crisis has afflicted the islands of Mayotte, Comoros Archipelago, since May 2018, although the origin is debated. Magnetotellurics (MT), which is sensitive to hydrothermal ...and/or magmatic fluids and can map the subsurface electrical resistivity structure, can provide insight by revealing the internal structure of the volcanic system. In this paper, we report the results of a preliminary land and shallow marine MT survey performed on and offshore the island nearest the crisis. The 3D inversion-derived electrical resistivity model suggests that the island is underlain by a shallow ~500-m-thick conductive layer atop a deeper, more resistive layer, possibly associated with a high-temperature geothermal system. At depths of ~15 km, the resistivity drops by almost two orders of magnitude, possibly due to partial melting. Further petrophysical and geophysical studies are underway for confirmation and to map the geometry and evolution of the volcanic system.
•A major seismovolcanic crisis has afflicted the islands of Mayotte since May 2018, although the origin is debated.•We report the results of a land and shallow marine MT survey performed on and offshore the island nearest the crisis.•Data suggests that the presence of a shallow conductive and a deep resistive layer, possibly linked to a geothermal system•At depths of ~15 km, the resistivity drops by almost two orders of magnitude, possibly due to partial melting.
Rift Valley fever (RVF) recently re-emerged in Mayotte. We described, for the first time, that the mosquito species Eretmapodites subsimplicipes, a highly abundant species in Mayotte, is a competent ...vector for the transmission of RVF virus using three distinct populations native to Mayotte. We also showed that Aedes albopictus specimens are able to transmit RVF virus (RVFV) as previously observed in mosquito populations of other countries emphasizing the need of the increase vigilance for this highly invasive species of global distribution. Altogether, these results underline the epidemiological importance of both species for RVFV transmission in Mayotte and contribute to better understand the RVF epidemiological cycle and help to implement efficient prevention measures.
We characterized a collection of IMI-like-producing Enterobacter spp. isolates (n = 112) in France. The main clone corresponded to IMI-1-producing sequence type 820 E. cloacae subspecies cloacae that ...was involved in an outbreak. Clinicians should be aware of potential antimicrobial resistance among these bacteria.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Since 2018, the submarine east flank of Mayotte Island (Comoros archipelago) is the site of a major eruption located at 3.5 km depth bsl on a WNW-ESE volcanic ridge. Samples brought by oceanographic ...cruises carried out to monitor this seismo-volcanic crisis indicate that this volcanic ridge is built by a bimodal sodic alkaline magmatic series that includes basanites and phonolites. A petrological study of dredged samples allowed us to image the magmatic system feeding the volcanic ridge and to determine the link between basanitic and phonolitic magmas. The magmatic system feeding the volcanic ridge comprises multiple levels of magma storage. Basanitic magmas generated at 80–100 km mantle depth are stored in two or more deep reservoirs (≥ 37 km) and then in shallower basanitic and phonolitic lenses located close to the Moho interface before rising the surface. This study identifies three possible scenarios: (1) the deep basanitic magma rises directly and quickly to the surface from the deep mantle reservoir (as is currently happening 60 km offshore), (2) the basanitic magma stalls in a shallower reservoir near the Moho before resuming its ascent toward the surface and erupting as porphyritic basanite, (3) the basanitic magma stops and evolves to phonolite in these sub-crustal reservoirs. The phonolitic lavas are produced by approximately 80% fractional crystallization (34% clinopyroxene, 30% anorthoclase feldspar, 15.5% magnetite, 12.5% olivine, 5% apatite and 4% ilmenite) of a hydrous basanitic magma at mantle depths (
P
> 0.6 GPa) under reduced oxygen fugacity (~ FMQ-1). In this third scenario, the phonolitic magma might be reactivated by the arrival of a new batch of deeper basanitic magma.
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