Sedimentary Architecture Prediction Using Facies Interpretation and Forward Seismic Modeling: Application to a Mediterranean Land–Sea Pliocene Infill (Roussillon Basin, France)
This study predicts sedimentary architectures and facies distribution within the Pliocene prograding prism of the Roussillon Basin (Gulf of Lion, France), developed along an onshore–offshore continuum. Boreholes and outcrops provide facies-scale observations onshore, while seismic data capture basin-scale structures offshore. Forward seismic modeling bridges spatial and scale gaps between these datasets, yielding characteristic synthetic seismic signatures for the sedimentary facies associations observed onshore, used as analogs for offshore deposits. These signatures are then identified in offshore seismic data, allowing seismic profiles to be populated with sedimentary facies without a well tie. Predicted offshore architectures are consistent with shoreline trajectories and facies successions observed onshore. The Roussillon prism records passive margin reconstruction in the Mediterranean Basin following the Messinian Salinity Crisis, through the following three successive depositional profiles marking the onset of infilling: (1) Gilbert deltas, (2) wave- and storm-reworked fan deltas, and (3) a wave-dominated delta. Offshore, transitions in clinoform type modify sedimentary architectures, influenced by inherited Messinian paleotopography. This autogenic control generates spatial variability in accommodation, driving changes in depositional style. Overall, this multi-scale and integrative approach provides a robust framework for predicting offshore sedimentary architectures and can be applied to other deltaic settings with limited land–sea data continuity.
(Geosciences. vol. 15, n° 2076-3263, pp. 383, 03/10/2025)
INSU - CNRS, CNRS, UA, UM, BRGM, CEFREM, UPVD, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, Bordeaux INP, UM, UMR G-EAU, Cirad, BRGM, IRD, INRAE, Institut Agro, UM
Carte morphostructurale sous-marine de la zone Comores-Mayotte-Glorieuses, nord du Canal du Mozambique
Au début de la crise sismo-volcanique de Mayotte (2018-présent), le constat a été fait du manque de connaissances géologiques du domaine immergé du nord du Canal du Mozambique permettant de fournir un contexte géodynamique régional aux évènements en cours. Les campagnes de recherche SISMAORE (Thinon et al., 2020) et SCRATCH (Berthod et al., 2021) et les campagnes de surveillance MAYOBS (Rinnert et al., 2019) ont largement enrichi les jeux de données géologiques et géophysiques. Les données bathymétriques et d’imagerie multifaisceaux acquises ont complété celles plus disparates provenant du SHOM et de l’Ifremer, mais ayant déjà donné lieu à des interprétations morphologiques (Audru et al., 2006 ; Tzevahirtzian et al., 2021). L’ensemble des données multifaisceaux acquises depuis 2004 a ainsi fait l’objet d’une compilation permettant d’obtenir une couverture suffisamment complète pour entreprendre une mise à jour fine de la cartographie à l’échelle du 1/250 000 sur les eaux des ZEE des Glorieuses, de Mayotte, des Comores et des Seychelles, et ce dans le cadre du projet ANR COYOTES. La carte produite sous SIG montre la distribution de plus de 2400 édifices volcanique sous-marins (cônes, fissures), parfois regroupés en chaînes volcaniques (ex : Mwezi-Jumelles, …) ou monts sous-marins (zone Glorieuses). Ces zones volcaniques montrent également des évidences d’intrusions de sills, se traduisant par des plis forcés présentant en surface des morphologies en dômes. De nombreuses failles sont cartographiés sur la plaine abyssale au nord des Comores et de Mayotte, associées notamment à des zones volcaniques orientées N160° (N’Drounde) ou N135° (Mwezi-Jumelles). L’interprétation morphologique permet également de mettre en évidence les processus d’érosion, transport et sédimentation depuis les plateformes carbonatées et les flancs volcaniques, jusqu’aux plaines abyssales. Le transport se fait sur les pentes insulaires ou continentales par le biais de canyons, mais également lors d’évènements gravitaires majeurs comme le montrent les loupes d’arrachements, les lobes, et la présence de milliers de blocs glissés. Le SIG associé à la carte présentée ici dans sa première version, pourra s’enrichir d’informations complémentaires au fil du temps et servir de base à de futures cartes thématiques (structurales s.s., typologie volcanique, âges obtenus sur les volcans sous-marins).
(01/10/2025)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, iSTeP, INSU - CNRS, SU, CNRS, CY, GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, LMV, IRD, INSU - CNRS, CNRS, UCA, UPCité
Reactive transport modeling of CO2 and CH4 plumes during a gas-rich water leakage in a shallow carbonate freshwater aquifer
The recent advances in geological carbon capture and storage and the worldwide proliferation of such projects to reach net-zero emissions by 2050 highlight the importance of investigating the risks associated with CO 2 leakage from carbon storage reservoirs into shallow aquifers. A recent experiment indicates that residual CH 4 from legacy hydrocarbon fields could be a potential early indicator of CO 2 leakage. In this study, numerical reactive transport simulations are performed to examine the reasons behind the different behavior of CH 4 in regard to CO 2 as well as its potential and limitations as a monitoring parameter. The base case model was calibrated using a large data set, including a tracer test, major element concentrations, dissolved CO 2 and CH 4 concentrations, and pH monitoring. The results show that the delay of CO 2 with respect to CH 4 is likely related to sorption, which plays a significant role in CO 2 retardation but has a minimal effect on CH 4 transport. The presence of clay minerals (montmorillonite and illite) did not significantly change the delay between the two gases. Furthermore, CO 2 retardation was found to increase in a scenario with a lower natural groundwater CO 2 concentration. The CH 4 oxidation simulation revealed that oxidation decreased the CH 4 concentration below the CH 4 concentrations from baseline water reported in the literature, suggesting that CH 4 oxidation is a critical process able to reduce the efficiency of CH 4 monitoring and should be considered if CH 4 monitoring is implemented.
(Applied Geochemistry. vol. 190, n° 0883-2927, pp. 106495, 01/10/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFPEN
Pulsed light treatment of pesticides induces high compound degradation and toxicity decrease
Pulsed light (PL) is a technology using high-intensity pulses of polychromatic light enabling the photolysis of various organic compounds. This study examined the photodegradation by PL of 18 pesticides commonly used in viticulture using both chemical and ecotoxicological approaches. Pesticide concentrations were monitored in treated and untreated samples, along with the formation of degradation products using HPLC-MS/MS. PL successfully degraded the 18 pesticides from initial concentrations between 304 and 561 µg/L to < 30 µg/L after a treatment at 91 J/cm2 for 8.53 min duration. The concentrations of 14 pesticides were even reduced below their limit of quantification, and for 10 of them, below their limit of detection. Dimethomorph was the least degraded compound, with a 93.5 % reduction. Besides, 42 degradation products were observed. The study also showed that PL can degrade the degradation products themselves. The ecotoxicological approach assessed the acute toxicity of the pesticide mix before and after PL on three levels of the aquatic trophic chain: the bacteria Aliivibrio fischeri, the microalgae Raphidocelis subcapitata, and the fish Oryzias latipes. Acute toxicity was reduced two-fold for A. fischeri and 24-fold for R. subcapitata. For O. latipes, a mortality rate of 6.6 % was observed in treated samples, whereas it was 100 % in untreated samples. However, some sublethal effects, such as axial skeleton deformations appeared in 22.2 % of O. latipes, likely due to residual pesticides and degradation products. These results demonstrate that PL is a promising process to significantly lower both pesticide concentrations and acute toxicity.
(Ecotoxicology and Environmental Safety. vol. 305, n° 0147-6513, pp. 119232, 01/10/2025)
OENO, UB, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB
A dynamic H2 system with multi-source methane in chromitite-rich ophiolitic settings
The generation and migration of hydrogen and methane in serpentinizing environments represent fundamental processes with implications for deep carbon cycling, the origin of life, and emerging carbon-free energy resources. Here we present an integrated geochemical study of gas emissions from the Bulqizë chromite mine in Albania, where exceptional underground access to depths exceeding 1000 m enables direct investigation of one of Earth's most intense natural hydrogen systems (~200 tones H₂/year). Through a comprehensive analysis of bulk and clumped isotopes, noble gases, molecular compositions, and structural controls, we report a novel occurrence of radiocarbon-bearing methane (3.76 ± 0.06 pMC; ~26 ka) in any ophiolite globally. This discovery, combined with modern water ages (³H = 3.5 TU; ¹⁴C-DIC = 95.8 pMC) yet ancient gas signatures, reveals a dramatically decoupled fluid systems where meteoric water circulates rapidly within the mine while gas migrates slowly from depth. Methane clumped isotopes (Δ¹³CH₃D = 2.52 ± 0.26‰; Δ¹²CH₂D₂ = 9.95 ± 1.6‰) indicate a lack of isotopic equilibrium with H₂ (δD-H₂ = -743.5 ± 1.1‰; ΔDD = 255 ± 35‰) and suggest formation from a single hydrogen source. They also show positive Δ¹²CH₂D₂ deviations likely due to diffusion or mixing, and point to a microbial origin probability of less than 10%. High δ¹³C-CH₄ values (-12.3‰), complete isotopic reversal in C₂-C₄ alkanes, and Volatile Organic Compounds signatures further support a predominantly abiotic synthesis. Noble gas and nitrogen isotopes reveal mixing between atmospheric (80-85%) and crustal (15-20%)
(Geochimica et Cosmochimica Acta. vol. 409, n° 0016-7037, pp. 281-307, 01/10/2025)
ISTerre, IRD, INSU - CNRS, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, UGA, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, ISTO, BRGM, INSU - CNRS, UO, CNRS, ISTO, BRGM, INSU - CNRS, UO, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, GET, IRD, INSU - CNRS, CNES, CNRS, EPE UT, Comue de Toulouse
Holocene environmental change in Singapore: Insights from sedimentary and foraminifera records
Holocene marine records provide key insights into environmental changes associated with changing relative sealevels under interglacial conditions. However, most Holocene records are found in the mid to high latitudes, and there is a lack of records in the tropics. Here, we present a multi-proxy record from a sediment core GRBH03 from the Kallang River Basin in Singapore, spanning from 9.1 to 1.2 cal kyr BP. Three sedimentary units and five foraminiferal assemblages were recognised, reflecting the successive environmental change during the early Holocene marine transgression and subsequent coastal progradation. A depositional hiatus of ~5.8 to 1.2 cal kyr BP and shell layer formed during this period may be associated with falling sea level after the mid-Holocene highstand. Stratigraphic interpretation, anchored by the Marina South Member (MSM), identifies Transgressive and Highstand Systems Tracts in the Kallang River Basin, though evidence for Falling Stage and Lowstand Systems Tracts is limited. From GRBH03, an abrupt increase in sedimentation rate from 8.4 to 8.2 cal kyr BP, with simultaneous increase in Fe/Ca and decrease in δ 13 C OM values, may reflect drier conditions linked to the 8.2 ka climate anomaly. These findings highlight the combined influence of relative sea-level and climate variability on depositional processes in tropical coastal systems and provide valuable analogues for anticipating coastal responses to future environmental change.
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 676, n° 0031-0182, 01/10/2025)
NTU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UA, LGO, UBS, IFREMER, UBO EPE, CNRS, NTU | EOS, NTU
Diffusive and advective flux measurements of trichloroethene from soil into a building: a case study
(Chemosphere. vol. 387, n° 0045-6535, pp. 144663, 01/10/2025)
LCE, AMU, INC-CNRS, CNRS
Understanding the relationship between foraminiferal Mg/Ca and clumped isotope thermometers
Reconstructions of past sea surface temperatures (SSTs) are essential for understanding long-term climate variability, yet different proxy methods can yield divergent results. In this study, we compare Mg/Ca-derived SSTs from Globigerinoides ruber sensu stricto and Trilobatus sacculifer with clumped isotope (Δ 47 ) SSTs measured on G. ruber s.s. from the same core, MD96-2048 (Indian Ocean), covering the last 1.25 million years (Ma). Using the same species and samples allows minimizing ecological and environmental biases. We find that Δ 47 -derived SSTs are systematically colder than Mg/Ca-SSTs prior to 0.4 Ma, while both proxies agree well after this point. This offset is not explained by diagenetic alteration (as assessed via SEM), nor by corrections for seawater salinity, pH, or Mg/Ca composition. The Mg/Ca-SSTs from T. sacculifer are more consistent with Δ 47 -SSTs in the older interval, but do not fully resolve the discrepancy. We found that the apparent Δ 47 -based cooling before 0.4 Ma is not supported by seawater δ 18 O estimates or other climate indicators. Our results suggest that Δ 47 -derived SSTs may be affected by an unknown bias in older intervals, although a combination of multiple factors explored in this study could also contribute to the observed offset.
(Geochimica et Cosmochimica Acta. vol. 407, n° 0016-7037, pp. 253 - 264, 01/10/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, VUB, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Quantitative structural geology in the deep ocean using photogrammetry: Implications for the polyphased tectonic evolution of the Buteur Ridge, French Guiana
The Buteur Ridge is a 7 km-long and 6 km-wide relief on the eastern rifted margin of the Demerara Plateau, offshore French Guiana. This margin was formed during the Lower Cretaceous. In early 2023, the oceanographic cruise DIADEM used a manned deep submersible (Nautile) to sample and directly observe the eastern flank of this 3750 m-deep ridge. This study presents a new underwater photogrammetric method developed from the Nautile video records. This method incorporates both camera and submarine movements to produce photogrammetric 3D models of the seafloor below decimetre scale. The presented underwater photogrammetric method can be used for both past and future video records, as long as both underwater device and camera movements are recorded. The data obtained from the 3D reconstructions allow to reconstruct detailed stratigraphic and structural framework of the Buteur Ridge. The eastern flank of the Buteur Ridge is entirely composed of sedimentary layers. Structural analysis at bed scale suggests prograding structures likely associated with a N-S-directed paleocurrent. At ridge scale, structural analysis combined with seismic observations suggests that the Buteur Ridge is the result of a polyphased tectonic evolution. We highlight that Cretaceous tilted blocks, bounded by east-dipping faults, are overlapped by a post-rift unit. The syn-rift units are in contact with the east-dipping post-rift unit by a post-rift unconformity. Subsequent tilt and fault reactivation offset both the post-rift unconformity and the post-rift unit, resulting in the present relief of the Buteur Ridge.
(Marine Geology. vol. 488, n° 0025-3227, pp. 107609 (19p.), 01/10/2025)
ISTerre, IRD, INSU - CNRS, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, UGA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS
From Carbon to Societal Footprint: Geoscience Research in the Face of the Socio-Environmental Emergency
(29/09/2025)
GR, UR, INSU - CNRS, CNRS, IMBE, AU, AMU, CNRS, IGE, IRD, INSU - CNRS, CNRS, INRAE, Fédération OSUG, UGA, Grenoble INP, UGA, IMPMC, MNHN, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCE, CNRS, UMLP, GET, IRD, INSU - CNRS, CNES, CNRS, EPE UT, Comue de Toulouse, HSM, IRD, INSU - CNRS, CNRS, UM, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE