Storm Wind Flow and Sediment Dynamics on Adjacent Coastal Dunes With Contrasting Morphologies During One Storm Event
This study presents the first high‐resolution spatial and temporal analysis of wind flow, sediment transport and topographic evolution under simultaneous storm conditions across two morphologically contrasting beach‐dune systems, characterized by a gently sloping dune face (11°) and a steep, scarped dune face (36°). Results demonstrate that the dune slope strongly controls near‐surface wind acceleration, the development of secondary airflow structures (amplitude, spatial positions), and the continuity of sediment transport pathways. Over the gentle slope, airflow accelerates progressively up the stoss face, promoting sustained, landward‐directed sediment fluxes across the entire beach–dune system and enabling efficient sediment recycling. In this configuration, beach‐derived contributions account for only 12%–15% of the total sediment flux. In contrast, the steep scarp induces flow deceleration and separation at the dune toe, limiting sediment transfer from the beach and favoring seaward‐directed transport associated with secondary vortices at the crest. These contrasting airflow organizations result in fundamentally different storm responses. The gently sloping dune undergoes landward translation with minimal net volume change, whereas the scarped dune experiences dominant marine erosion, leading to a 4 m retreat of the dune front and a sediment loss of ∼30 m 3 m −1 . A new conceptual model of storm‐driven airflow over contrasting dune morphologies is proposed, illustrating how inherited dune slope governs airflow structure and circulation patterns. Overall, these results identify inherited dune morphology as a primary control on airflow organization, sediment pathways, and dune resilience during extreme events.
(Journal of Geophysical Research: Earth Surface. vol. 131, n° 2169-9003, 02/02/2026)
CEFREM, UPVD, INSU - CNRS, CNRS, BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ONF
Early Pleistocene (1.94–1.46 Ma) records for the upper Mediterranean Outflow Water branch reveal low and high latitude climate influences
The Mediterranean Outflow Water (MOW), modified by paleoceanographic conditions and tectonic processes, played a significant role in the formation of sediments drifts along the Iberian Margin. Using sediment samples from IODP Hole U1387C, we explore the Early Pleistocene history of the upper MOW core above the central Faro Drift in the Gulf of Cádiz. The time series of benthic foraminifer stable isotope and grain size related data have a rigorous stratigraphic framework consisting of nannofossil biostratigraphy and paleomagnetic and δ 18 O stratigraphy. The paleoenvironmental records are supplemented by natural gamma ray downhole logging data. Above the hiatus associated with the youngest dolostone, sandy to muddy contourite sedimentation started at 1.946 Ma, i.e., within Marine Isotope Stage (MIS) 74, at IODP Site U1387, slightly younger than at IODP Site U1389. Formation of contourite layers, reflected in the sortable silt and sand percentage records, strongly reacted to precession forcing, including semi-and quarter-precession cycles. The majority of the contourite beds developed during stadial (colder) climate periods, like previous observations from the Early to Late Pleistocene. Formation of contourite layers within MIS 53, MIS 55 and MIS 65, however, appear to be linked to the prevailing atmospheric conditions over North Africa. Periods of poor ventilation in the upper MOW were linked to insolation maxima and reduced ventilation in the Mediterranean Sea. Here, MIS 51 presents a peculiar case as poor ventilation reached from the surface to the lower North Atlantic Deep Water range, reflecting unique interglacial conditions that merit future exploration.
(Marine Geology. vol. 492, n° 0025-3227, 01/02/2026)
IPMA, CCMAR, UAlg, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UC Santa Cruz, UC, UC Davis, UC, NOC, INSU - CNRS, CNRS, UA, UM, LNEG, MARUM, TAMU
Exploring the environmental distribution of the oyster parasite Haplosporidium costale
The protozoan parasite Haplosporidium costale is known to occur in the USA where it has been associated with sharp seasonal mortality of the Eastern oyster Crassostrea virginica since the 1960’s. In 2019, the parasite was detected for the first time in the Pacific oyster Magallana gigas in France in the context of light mortality and was subsequently detected in archived material collected since 2008. This detection raised several questions regarding the ability of the parasite to maintain in the ecosystem and the potential involvement of other species in its life cycle. To answer these questions, an integrated sampling approach was deployed seasonally in three oyster farming areas where the parasite was already known to occur. Parasite presence was evaluated after checking the presence of PCR inhibitors and using a previously developed and validated Real Time PCR assay, optimized in this study to detect parasite DNA in various environmental compartments. Parasite DNA was almost only detected in cupped oysters. Considering the high number of oysters found positive with low infection intensity, a complementary experiment was undertaken to better characterize sub-clinical infections in oysters. The presence of the parasite was tested twice a week in water and sediment from aquaria hosting cupped oysters from a known infected site. After one month, oysters were sacrificed and tested regarding the presence of the parasite at the tissular level. Altogether, field and experimental results indicate that the parasite is stably established in oyster, particularly in gills, which may act as a reservoir all along the year. The detection of parasite DNA in nanoplankton and sediment suggests that H. costale is released from the oysters outside mortality event. Our results do not support the involvement of other species than cupped oyster in the parasite life cycle except periwinkles, whose role would deserve to be further investigated
(Journal of Invertebrate Pathology. vol. 214, n° 0022-2011, pp. 108462 (9p.), 01/02/2026)
ASIM, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A synthesis of biostratigraphic, isotope-stratigraphic, and paleoenvironmental records from the Callovian (Middle Jurassic) carbonate succession of Saudi Arabia and its global implications
The Middle Jurassic Callovian Stage (~165.2-160.8 Ma) represents a pivotal interval in Earth's history marked by climate change, both warming and cooling (glacio-eustasy), widespread organic matter accumulation, and perturbations in the carbon cycle. On the Arabian Plate, this stage witnessed the initiation of intrashelf basins, large-scale coral-stromatoporoid reef growth, and a glacio-eustatic sea level fluctuation. Detailed global reconstructions are, however, hindered by discontinuous stratigraphic records, significant hiatuses, and a lack of integrated datasets. Here we present a synthesis of sedimentological, biostratigraphic, chemostratigraphic, and paleoenvironmental data from a well preserved and extended (290 m thick) carbonate-dominated Callovian succession in Saudi Arabia, which is continuously exposed along a >1000 km long escarpment. We integrate legacy datasets of dispersed reports and theses, produced during the mapping campaigns in the 1980s-1990s, with reinterpreted published carbon-isotope curves and a new sedimentological section, with refined calcareous nannofossil biostratigraphy, using modern taxonomy, standardized biozonation, and a Bayesian age model. The C-isotope curve shows an early Callovian positive δ 13 C excursion in the upper part of the gracilis Ammonoid Zone, followed by a negative shift at the base of the anceps Zone coinciding with siliciclastic influx from the Arabian shield. δ 13 C values rise through the Middle Callovian global warming with enhanced organic carbon burial on the Arabian Plate. The late Callovian cooling phase records extensive coral-stromatoporoid bioherms terminated by a sea-level fall near the Callovian-Oxfordian boundary. This work establishes the Arabian Plate as a key northern Gondwanan reference point for Callovian chronostratigraphy and calibration of global paleoceanographic, depositional, and climatic trends.
(Earth-Science Reviews. vol. 273, n° 0012-8252, 01/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
On the performance of radiocarbon and quartz OSL dating in macrotidal estuarine environments: Four case studies from Western France
The study of estuarine sedimentary archives provides valuable insights into their geomorphological evolution over the past two centuries, enhancing our understanding of estuarine responses to climate change. Establishing a reliable and precise geochronological framework is therefore essential for monitoring these changes. This study evaluates the performance of quartz Single-Aliquot Regenerative (SAR) OSL and AMS 14C dating in four estuaries along the western coast of France. The results are compared with cartographic data, serving as an independent age control. Of the 14 OSL dated samples, 10 yield depositional ages consistent with cartographic data, whereas the remaining 4 appear to overestimate ages by 20–100 years. In contrast, AMS 14C dating reveals numerous stratigraphic inversions, with at least 12 out of the 16 measured samples overestimating the depositional age in some cases by up to 5000 years, in total disagreement with cartographic data. The discrepancy between the OSL and radiocarbon ages reflects the constant reworking of allochthonous material, to which is added the further uncertainty associated with the local reservoir age. These factors fundamentally limit the reliability of 14C dating regardless of the material analyzed. By contrast, the OSL signal displays remarkable resilience, with any age overestimation linked to partial bleaching remaining minor (on the order of decades) compared with the errors affecting 14C ages. This underscores the capacity of OSL dating to resolve short-term environmental changes and positions it as the most reliable tool for constructing high-resolution chronologies of the last centuries in macrotidal estuarine settings.
(Quaternary Geochronology. vol. 92, n° 1871-1014, pp. 101723, 01/02/2026)
M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, DTU, UCPH, LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST, Nantes Univ, Cerema, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Unraveling the Effects of Fe Incorporation on High-Performance Water-Splitting Photoanodes
Although it is known that iron (Fe) significantly alters the electrocatalytic activity of nickel (Ni)-based materials, little attention has been paid to the effects of Fe impurities on the photoelectrochemical (PEC) properties of solar-driven watersplitting photoanodes. Herein, we elucidate the crucial role of Fe in model metal-insulator-semiconductor (MIS) Si photoanodes decorated with Ni nanoparticles (NPs), known for their high performance in photoinduced water splitting. Our results demonstrate that residual Fe strongly influences the photoanodes' junction energetics and photovoltaic properties. We show that the synergistic effects (electrocatalytic/photovoltaic) caused by Fe doping explain the high performance previously reported for these model photoanodes. Crucially, Fe incorporation into the outer shell of Ni NPs and the electrolyte is essential to achieve the reported photovoltage up to 500 mV. Our investigations emphasize the importance of Fe in PEC devices, which has always been neglected in the past.
(Journal of the American Chemical Society. vol. 148, n° 0002-7863, pp. 5508-5519, 27/01/2026)
ISM, UB, INC-CNRS, CNRS, VISTEC, C2N, CNRS, LC, ENS de Lyon, UCBL, INC-CNRS, CNRS, THEO, LC, ENS de Lyon, UCBL, INC-CNRS, CNRS, CRPP, UB, INC-CNRS, CNRS, IEK-9, FZJ, IMS, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Diapiric ridges and minibasins in the Central High Atlas: impact on geometries and facies distribution (Lower-Middle Jurassic, Morocco)
The Central High Atlas of Morocco is the result of the Alpine tectonic inversion of an intracontinental Mesozoic basin, the infill of which started with thick Upper Triassic clay and evaporite deposition. This slightly deformed mountain range is characterized by narrow ENE-WSW ridges that expose a Triassic core. These ridges bound unique synclines filled by thick Jurassic successions showing well-preserved halokinetic depositional sequences, interpreted as salt-related minibasins. This paper aims to describe and analyze the evolution of diapiric movements and their interactions with Lower and Middle Jurassic carbonate dominated sedimentation in the Imilchil area, which corresponds to the axial part of the Atlas basin. Four diapiric ridges have been identified in this region: the Tasraft, Tassent, Ikkou, and Amagmag, which expose Triassic shales and are intruded by Triassic and Jurassic magmatic rocks. These ridges delineate three minibasins: Ikassene, Lakes (Lake Plateau), and Tilmi (Ikkou), each 5 to 10 km wide, preserving over 6,000 m of Upper Liassic and Dogger deposits. The Atlas basin is filled with five third-order transgression-regression cycles organized as one regressive megasequence. This long regressive trend is expressed by the succession of three depositional systems: i) a distal to proximal carbonate ramp system from the Toarcian to Late Bajocian; ii) a shallow mixed carbonate-siliciclastic system from the Late Bajocian to Early Bathonian; and iii) a fluvial system from the Bathonian to Early Callovian. Throughout this period, the development of coeval diapiric ridges significantly influenced these sedimentary systems, though the intensity of the diapiric activity varied over time. During the Late Bajocian, ridge growth slowed considerably amid the peak progradation of the carbonate systems. It then increased significantly from the latest Bajocian onward, due to a drastic rise in siliciclastic flux and sedimentation rate in the Atlas basin. The effects of diapirism on sedimentation are observed regionally (several kilometers), as minibasins evolve as depocenters, each exhibiting distinct subsidence rates and sedimentary thicknesses. Despite these local variations, the regional scale paleogeography and the sequential organization of the deposits remained largely unaffected. On a smaller scale (hectometers to kilometers), diapiric structures are always characterized by halokinetic depositional patterns. Internal angular unconformities only occur in very shallow-marine to continental deposits during periods of maximum ridge growth and subaerial exposure (notably in the Bathonian). At this scale, diapiric movements lead to local facies variations within shallowmarine deposits, fostering the development of bioconstructed or grainy carbonate sediment bodies along the ridges. However, in outer ramp environments, the submarine topographies created by ridge growth were generally insufficient to induce similar facies variations.
(Bulletin de la Société Géologique de France, n° 0037-9409, 21/01/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB, UAB, GEO3BCN–CSIC, CSIC
A critical role of heterotrophic bacteria in early diagenesis of carbonates through exopolymer degradation and calcium release.
The degradation of exopolymeric substances (EPS) by heterotrophic bacteria, concomitant release of calcium ions and precipitation of carbonates were studied in a temperate mountain lake, Lac d'Ilay, Jura France. Phytoplankton blooms in this lake produced large amounts of exopolymeric substances (EPS; 1.8–3.0 mg L −1 ), probably inhibiting CaCO 3 precipitation by binding Ca 2+ as shown by the saturation index of calcite and aragonite remaining well below 1. EPS settled to the sediments, where additional polymeric substances were produced by the benthic community. The total amount of EPS decreased downcore from ca 50 μg/g dry sediment near the surface to ca 1.5 μg/g dry sediment at the bottom (120 cm depth). A decrease in acidity, protein and sugar content, and calcium‐binding capacity of EPS with depth coincided with active calcite precipitation. Aerobic and anaerobic EPS‐degrading heterotrophic enrichments were obtained from the top, middle and bottom of the core. Doubling times of aerobic cultures from the top were six times shorter than those of cultures obtained from the bottom of the core, but anaerobic growth rates were similar across all enrichments. Aerobic turnover rates of organic compounds decreased by a factor of 4–5 from top to bottom; anaerobic rates were similar at all depths, except for the turnover of polymers, which was negligible at the surface compared to rates at the middle and bottom. All enrichments released calcium when grown on EPS. Growth on calcium‐saturated EPS in anaerobic cultures obtained from the bottom of the core was the slowest, but still released 26% of the Ca in 20 days. This release during EPS degradation explained an increase in free calcium ions with depth reported in a previous study and may account for a large fraction of the carbonate mud. This suggests that sediments should be considered as an important source of biogenic carbonates.
(Depositional Record. vol. 12, n° 2055-4877, pp. e70057, 16/01/2026)
UCONN, BGS, EPHE, PSL, CNRS, UBE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, Unibas, UNSW, UNC, UNC
Salinity Transition in the Ostia Lagoon During the Roman Period: Assessing the Feasibility of Salt Exploitation
This study examines long‐term salinity changes in the Ostia Lagoon between the 4th century cal BC and the 6th century cal AD , with emphasis on their implications for ancient salt production. Although Ostia's foundation is closely linked to the control of salt resources in the Tiber Delta, direct archaeological evidence of Roman‐period saltworks is scarce. To address this gap, this study combines micropalaeontological analysis of ostracod assemblages with a morphometric study of sieve pore features in Cyprideis torosa (Jones, 1850). This approach enables reconstruction of short‐term palaeosalinity dynamics. Core LOA–1 documents a transition from peatland to euryhaline lagoon between the 8th–6th and the 4th–3rd centuries cal BC , followed by repeated high‐salinity episodes. A notable peak coincides with the establishment of the Roman Castrum, suggesting favourable conditions for salt concentration. After the mid‐4th century cal BC , salinity peaks decreased, possibly reducing the lagoon's potential for saltworks and fostering greater reliance on the Maccarese saltworks. In the northern lagoon sector, hyperhaline conditions during the Roman period remain uncertain because of chronological gaps and the lack of sieve pore analysis. Overall, the results demonstrate both the potential and limitations of ostracod analysis as a palaeosalinity proxy and refine understanding of salt exploitation in the Tiber Delta. This study provides valuable insights into the long‐term socio‐environmental dynamics of the Mediterranean coastal wetlands, contributing to the advancement of geoarchaeological research on ancient salt production through salterns and its influence on human settlement patterns and economic practices.
(Geoarchaeology: An International Journal. vol. 41, n° 0883-6353, 10/01/2026)
Archéorient, UL2, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IGAG, CNR, CNRS, LIVE, UNISTRA, CNRS, ISCR
Tackling global change: integrated approaches for people and environment
(09/01/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EABX, INRAE, ECLA, USMB [Université de Savoie] [Université de Chambéry], INRAE, OFB, UB, CNRS, INRAE