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Onset of strong Iceland-Scotland overflow water 3.6 million years ago
No full textInternational audienceNorth Atlantic Deep Water (NADW), the return flow component of the Atlantic Meridional Overturning Circulation (AMOC), is a major inter-hemispheric ocean water mass with strong climate effects but the evolution of its source components on million-year timescales is poorly known. Today, two major NADW components that flow southward over volcanic ridges to the east and west of Iceland are associated with distinct contourite drift systems that are forming off the coast of Greenland and on the eastern flank of the Reykjanes (mid-Atlantic) Ridge. Here we provide direct records of the early history of this drift sedimentation based on cores collected during International Ocean Discovery Programme (IODP) Expeditions 395C and 395. We find rapid acceleration of drift deposition linked to the eastern component of NADW, known as Iceland–Scotland Overflow Water at 3.6 million years ago (Ma). In contrast, the Denmark Strait Overflow Water feeding the western Eirik Drift has been persistent since the Late Miocene. These observations constrain the long-term evolution of the two NADW components, revealing their contrasting independent histories and allowing their links with climatic events such as Northern Hemisphere cooling at 3.6 Ma, to be assessed
Plastics : from the rivers to the ocean
No full textThe Indian Ocean is facing serious plastic pollution, which needs to be curbed as a matter of urgency - and research data can help
The unsuspected variability of lagoons
No full textIn Africa, two-thirds of the population live less than 100 km from the coast, exerting significant pressure (fishing, pollution, development, etc.) on coastal ecosystems, particularly lagoons
Our shared ocean : science in the global south for a sustainable world
No full textThe ocean is a reserve of biodiversity, it regulates the climate and provides a wealth of resources. It is one of our most essential common assets. Given the urgent need for international mobilisation in order to preserve it, science must play a leading role. This book explores the major advances in interdisciplinary research into the ecological, economic and social challenges facing the oceans, which are particularly complex and prominent in the tropical zone, due to the unique characteristics of the oceans in this part of the world.The aim of this richly illustrated educational book is to highlight the many facets of the ocean, as well as solutions for protecting it, through dialogue between all stakeholders. It will captivate anyone with a passion for science and a desire to understand the complexity of the world
Hydrodynamic behavior of organo-phosphatic bioclastic sediments: An experimental study on linguliform brachiopod shell fragments
No full text(IF 2.8; Q1)International audienceBioclastic phosphorites composed of linguliform brachiopod shell debris remain largely unexplored from a sedimentological, process-oriented perspective. Understanding the hydrodynamic behavior of these low-density, platy sediments is essential for elucidating the concentration mechanisms driving their accumulation. The present experimental study delves on this issue through the determination of settling velocity and critical shear velocity of organo16 phosphatic bioclasts derived from extant Lingula anatina shells (Brachiopoda: Linguliformea). 137 settling velocity determinations were obtained through stroboscopic photography of the particles’ trajectories in a settling tube. 30 critical shear velocity determinations of five sieve fractions were acquired from flow profiles measured in flume experiments. Additionally, Lingula anatina shell density is here reported for the first time. Organo-phosphatic bioclasts present low particle densities (1040–1734 kg/m3), which combined with their platy shape grant them low settling velocities and critical shear velocities comparable to siliciclastic sediments. They thus present a tendency to be easily transported once set in motion coupled with significant resistance to erosion, defining a dual hydrodynamic behavior like the one reported in platy carbonate sediments. Their resistance to erosion, despite their relatively low submerged weight, is here hypothesized to be explained by shape effects such as elevated intergranular friction forces, large pivoting angles and low degree of exposure to the flow. In terms of settling, gravel-sized organo phosphatic bioclasts are equivalent to fine-to-coarse-sized siliciclastic sand; this reflects the textural characteristics of many ancient phosphorite deposits, suggesting that settling equivalence played a role in their deposition and that the common conception of phosphatic particles as a heavy, relatively immobile component is not readily applicable to organo-phosphatic bioclasts. These results shed light on the sedimentology of ancient bioclastic phosphorites and contribute to the still underexplored field of biogenic sediment transport
Euclid Quick Data Release (Q1) The Strong Lensing Discovery Engine B -- Early strong lens candidates from visual inspection of high velocity dispersion galaxies
No full textInternational audienceWe present a search for strong gravitational lenses in Euclid imaging with high stellar velocity dispersion ( km/s) reported by SDSS and DESI. We performed expert visual inspection and classification of \Euclid images. We discovered 38 grade A and 40 grade B candidate lenses, consistent with an expected sample of 32. Palomar spectroscopy confirmed 5 lens systems, while DESI spectra confirmed one, provided ambiguous results for another, and help to discard one. The \Euclid automated lens modeler modelled 53 candidates, confirming 38 as lenses, failing to model 9, and ruling out 6 grade B candidates. For the remaining 25 candidates we could not gather additional information. More importantly, our expert-classified non-lenses provide an excellent training set for machine learning lens classifiers. We create high-fidelity simulations of \Euclid lenses by painting realistic lensed sources behind the expert tagged (non-lens) luminous red galaxies. This training set is the foundation stone for the \Euclid galaxy-galaxy strong lensing discovery engine
Le squelette postcrânien des Néandertaliens de Goyet (Belgique) : estimation de la stature, analyse bio-mécanique et implications pour une accumulation d’origine anthropique
No full textInternational audienceLe site de la Troisième caverne de Goyet a livré un grand nombre de restes néandertaliens datés du stade isotopique marin 3 (40,5–45,5 ka calBP). Plusieurs de ces restes présentent des modifications anthropiques, suggérant une accumulation d’origine humaine ainsi qu’une utilisation de certains ossements comme retouchoirs. Cette étude présente les premiers résultats de la caractérisation biologique et comportementale des Néandertaliens de Goyet, s’appuyant notamment sur une analyse morphologique et structurelle de certains os longs des individus, visant à estimer leur stature, à évaluer leur robustesse et à formuler des hypothèses sur leur mobilité en comparaison avec d'autres groupes néandertaliens.Sept tibias et trois fémurs fragmentaires, identifiés comme néandertaliens, ont été analysés. Les longueurs maximales et biomécaniques ont été estimées à l'aide des méthodes ostéométriques les plus appropriées ou déduites à partir de restes néandertaliens plus complets. Ces données ont permis d'estimer la stature des individus, tandis que l'analyse de la structure interne des ossements a été réalisée en utilisant une approche par géométrie de section afin de déterminer leurs propriétés biomécaniques.Les résultats indiquent une stature estimée entre 158 et 167 cm pour l’ensemble du groupe, situant les individus de Goyet dans la variabilité basse des Néandertaliens du Pléistocène supérieur. L’analyse biomécanique révèle une faible robustesse osseuse du membre inférieur, tandis que le modèle de répartition de la corticale des diaphyses des tibias suggère une mobilité réduite au sein du groupe.Ces observations indiquent que les ossements appartiennent à un groupe phénotypiquement homogène d'individus relativement graciles. Ces résultats permettent d’émettre l’hypothèse d’une sélection privilégiant des individus graciles à l’origine de l’accumulation anthropique des restes néandertaliens de Goyet
Thank You to Our 2024 Reviewers and Volunteers
No full textInternational audienceAt JGR: Planets, the peer review process is critical to ensuring that the published articles are based on sound scientific principles, follow state‐of‐the‐art techniques while acknowledging relevant prior results, and present exciting discoveries or novel understanding of the fundamental processes that affect solar system objects. JGR: Planets covers a broad range of topics addressing every aspect of geoscience with the only requirement that the work addresses planetary processes. The wide breadth of topics published is reflected by our editorial team composed in 2024 of associate editors Adrian Brown, Jun Cui, Joel Davis, Leigh Fletcher, Sierra Ferguson, Yang Liu, Ananya Mallik, Germán Martínez, Anna Mittelholz, Molly McCanta, Katarina Miljkovic, Naomi Murdoch, Ryan Park, Arianna Piccialli, Laura Schaefer, Mariek Schmidt, Yasuhito Sekine, Kelsi Singer, Michael Sori, Norihiko Sugimoto, Jamey Szalay, David Trang, and Zhiyong Xiao in addition to the editors who authored this note. We rely on the expertise of the community to vet the articles submitted to the journal. In 2024, JGR: Planets benefited from 1,269 reviews provided by 816 unique volunteer referees. We also received help from organizers and guest editors working on eight active special collections. To these volunteers: We are truly grateful that you chose to dedicate your time and energy to evaluate manuscripts and to advise us on the suitability of each manuscript for JGR: Planets, often suggesting ways to improve the papers. We know that all our volunteers juggle many duties, both professional and personal. On behalf of the entire editorial board of JGR: Planets, we express our heartfelt gratitude to the many scientists who support this journal. Thank you! You are performing a valued service to this journal and to the community
Euclid Quick Data Release (Q1): From images to multiwavelength catalogues: the Euclid MERge Processing Function
No full textInternational audienceThe Euclid satellite is an ESA mission that was launched in July 2023. \Euclid is working in its regular observing mode with the target of observing an area of with two instruments, the Visible Camera (VIS) and the Near IR Spectrometer and Photometer (NISP) down to () in the Euclid Wide Survey. Ground-based imaging data in the \textit{ugriz} bands complement the \Euclid data to enable photo- determination and VIS PSF modeling for week lensing analysis. Euclid investigates the distance-redshift relation and the evolution of cosmic structures by measuring shapes and redshifts of galaxies and clusters of galaxies out to . Generating the multi-wavelength catalogues from \Euclid and ground-based data is an essential part of the \Euclid data processing system. In the framework of the \Euclid Science Ground Segment (SGS), the aim of the MER Processing Function (PF) pipeline is to detect objects in the \Euclid imaging data, measure their properties, and MERge them into a single multi-wavelength catalogue. The MER PF pipeline performs source detection on both visible (VIS) and near-infrared (NIR) images and offers four different photometric measurements: Kron total flux, aperture photometry on PSF-matched images, template fitting photometry, and Sérsic fitting photometry. Furthermore, the MER PF pipeline measures a set of ancillary quantities, spanning from morphology to quality flags, to better characterise all detected sources. In this paper, we show how the MER PF pipeline is designed, detailing its main steps, and we show that the pipeline products meet the tight requirements that Euclid aims to achieve on photometric accuracy. We also present the other measurements (e.g. morphology) that are included in the OU-MER output catalogues and we list all output products coming out of the MER PF pipeline
Euclid Quick Data Release (Q1). The Euclid view on Planck galaxy protocluster candidates: towards a probe of the highest sites of star formation at cosmic noon
No full text18 pages, 11 figures. Submitted to A&AWe search for galaxy protoclusters at redshifts z > 1.5 in the first data release (Q1) of the survey. We make use of the catalogues delivered by the Science Ground Segment (SGS). After a galaxy selection on the magnitude and on the photometric redshift quality, we undertake the search using the algorithm, an overdensity finder based on Delaunay tessellation that uses photometric redshift probability distributions through Monte Carlo simulations. In this pilot study, we conduct a search in the 11 tiles that contain previously known high star-forming galaxy protocluster candidates and focus on the two detections that coincide with these regions. These counterparts lie at photometric redshifts and and have both been confirmed by two other independent protocluster detection algorithms. We study their colours, their derived stellar masses and star-formation rates, and we estimate their halo mass lower limits. We investigate whether we are intercepting these galaxy overdensities in their `dying' phase, such that the high star-formation rates would be due to their last unsustainable starburst before transitioning to groups or clusters of galaxies. Indeed, some galaxy members are found to lie above the main sequence of galaxies (star-formation rate versus stellar mass). These overdense regions occupy a specific position in the dark matter halo mass / redshift plane where forming galaxy clusters are expected to have experienced a transition between cold flows to shock heating in the halo. Finally, we empirically update the potential for galaxy protocluster discoveries at redshift up to (wide survey) and (deep survey) with for the next data release (DR1)