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101. Phase transition induced stresses and their implications for deep earthquakes

Author: Marcel Thielmann, Einat Aharonov, Philippe Yamato, Thibault Duretz, Universität Bayreuth, Christian-Albrechts-Universität zu Kiel (CAU), University of Jerusalem, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Goethe-Universität Frankfurt am Main, and European Geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract: International audience; The nucleation and rupture processes of deep-focus earthquakes have remained enigmatic ever since their discovery. These earthquakes occur mostly within the mantle transition zone where brittle failure is extremely unlikely due to the elevated pressures at these depths. Hence, other mechanisms have to be invoked to explain the occurrence of these events. To date, two main hypotheses have been put forward to explain deep focus earthquakes: transformational faulting (due to the polymorphic phase change of metastable olivine to either wadsleyite or ringwoodite) and thermal runaway (due to the conversion of deformational work to heat). More recently, it has been proposed that the feedback between those two mechanisms may explain the observed two-stage ruptures of large deep-focus earthquakes.To better understand the potential feedback between transformational faulting and thermal runaway, it is necessary to determine the stresses induced by the phase change due to i) the grain size reduction and corresponding viscosity reduction of the transformed material and ii) the volume reduction of the transformed phase. The former process triggers a stress transfer from the transformed material to the untransformed material, whereas the latter results in elevated stresses around the transformed phase.In this study, we employ numerical models with a viscoelastic compressible rheology to quantify the stress levels and patterns resulting from both processes. To gain a better understanding of the parameters controlling the stress transfer from transforming regions to the surrounding matrix, we employ simplified numerical models where transforming regions are approximated using elliptical inclusions. In a second step, more realistic model geometries are used to additionally study the effect of the morphology of transformed regions on stress levels and heterogeneities.Results show that both processes result in significantly different stress evolution upon a phase transition. Whereas a phase transition affecting only the viscosity of the transformed material results in moderate stress increases which occur on relatively long timescales, a phase transition affecting both viscosity and density results in significantly larger stresses, which also exhibit a significantly faster build-up. In both cases, the attained stress are sufficiently large to activate additional ductile weakening mechanisms that could trigger ductile ruptures. The higher stress levels resulting from the combined effect of a viscosity and density change would likely result in stronger weakening effects and faster occurrence of ductile failure
Published: 2023

102. Southwestward tilting of the Ordos Loess Plateau, central China: topographic response to India-Asia convergence deduced from drainage systems

Author: Mengyue Duan, Franz Neubauer, Jörg Robl, Xiaohu Zhou, Moritz Liebl, Anne-Laure Argentin, Yunpeng Dong, Flora Boekhout, Paris Lodron University of Salzburg - Department of Environment and Biodiversity, State Key Laboratory of Continental Dynamics, Northwest University (Xi'an), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and European Geosciences Union
Subjects: [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology
Abstract: International audience; The Ordos Loess Plateau with its iconic fluvial incision pattern represents an uplifted but internally stable plateau crustal block on the eastern fringe of the Tibetan Plateau. The Ordos Loess Plateau deeply incised river landscapes and hence its inaccessibility helped to protect ancient China from invading nomads from the north. The Ordos Block is internally free of seismicity but its boundaries feature severe high-magnitude earthquakes. Due to the ongoing India-Asia convergence, the northeastward expansion of the Tibetan Plateau leading to the eastward lateral extrusion of fault-bounded blocks. The Ordos Loess Plateau is part of one of these blocks and is still affected by lateral eastward motion along crustal scale faults and large surface uplift from Late Miocene to present. In this study, we investigated the effect of fault activity on the morphological evolution of the Ordos Loess Plateau. To quantify the effect of uplift gradients on the drainage systems, we investigated topographic patterns and landform metrics through field surveys and topographic analysis based on digital elevation models. Field surveys show that the southern boundary of the Ordos Loess Plateau to the Weihe Graben is still tectonically active (evidence for faulting in quaternary sediments). We found that the drainage is consistently directed towards the Weihe Graben in the southeast. Fluvial channels are in a state of morphological disequilibrium, with steep channel segments towards the Weihe Graben and meandering low gradient rivers in the central Ordos Loess Plateau. Over substantial portions, the shape of the longitudinal channel profile in the Ordos Loess Plateau is straight and deviates from usual graded longitudinal channel profiles. We further found that the degree of erosion and plateau incision is pronounced in the eastern part of the Ordos Loess Plateau, while the southwestern part is less incised. The drainage network indicated that the drainage basins are tilted toward the Liupanshan Mountains overthrust in the southwest. We conclude that the far-field influence of the Cenozoic uplift of the Tibetan Plateau activated the southwestern and southern boundary faults around the Ordos Loess Plateau. The drainage systems reorganized to a principal southern flow direction and thereby progressively incised in the Ordos Loess Plateau, causing severe soil erosion.
Published: 2023

103. Accurate quantification of sediment conveyance following the 2016 Kaikoura earthquake, New Zealand

Author: Katie Jones, Jamie Howarth, Chris Massey, Pascal Sirguey, Dimitri Lague, Thomas Bernard, GNS Science, Victoria University of Wellington, University of Otago [Dunedin, Nouvelle-Zélande], Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and European Geosciences Union
Subjects: [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology
Abstract: Evaluating the influence of earthquakes on erosion, landscape evolution and sediment-related hazards requires quantifying the volume and velocity of post-seismic sediment cascades. However, accurate estimates of post-earthquake sediment transfers remain rare. Following the 2016 MW7.8 Kaikōura earthquake in New Zealand, the volume of post-seismic erosion was quantified directly by measuring the ground surface change between 4 lidar surveys captured in 2016, 2017, 2019 and 2021 using the multiscale model-to-model cloud comparison (M3C2) algorithm. The lidar surveys covered the 62 km2 Hapuku and 66 km2 Kowhai river catchments within the Seaward Kaikōura Range, representing the two catchments with the highest density of co-seismic landsliding.The total co-seismic landslide source volume for the Hapuku Catchment was 30 ± 6 M m3,the catchment being dominated by a 17 M m3 rock avalanche which dammed the Hapuku River. In the 5 years after the earthquake a total of 10.60 ± 0.22 M m3 of sediment was post-seismically eroded (equivalent to ~26% of the co-seismic landslide debris volume when considering bulking of the landslide deposit). A total of 9.71 ± 0.23 M m3 of sediment was delivered to the riverbed resulting in considerable riverbed aggradation and 3.58 ± 0.28 M m3 was inferred to have been transported beyond the rangefront of the Seaward Kaikōura Range (equivalent to ~9% of the co-seismic landslide debris). The total co-seismic landslide source volume for the Kowhai Catchment was only 13 +4/-3 M m3. Over the 5 years 2.02 ± 0.10 M m3 of sediment was post-seismically eroded, equal to ~13% of the co-seismic landslide debris volume within the catchment. The volume delivered to the riverbed, 1.29 ± 0.10 M m3 and 0.85 ± 0.13 M m3 is presumed to have been transported beyond the rangefront (equivalent to ~5% of the co-seismic landslide debris).From these volumes, the rates at which the co-seismic landslide sediment was eroded from hillslopes, delivered off-slope to channels and exported from the range front were calculated. When projected, these rates of sediment conveyance suggest the volume of co-seismically generated sediment is likely to be evacuated from the rangefront within or close to the recurrence interval for ground motions equivalent to the Kaikōura earthquake. The Hapuku and Kowhai river catchments being examples of where co-seismic landsliding counterbalanced uplift.
Published: 2023

104. Source-to-sink system evolution of the Nile since 70 Ma

Author: Iwan Setiawan, François Guillocheau, Cécile Robin, Jean Braun, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), and European Geosciences Union
Subjects: [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy
Abstract: Nile River, the longest river in the world (>6,500 km), has been studied since long time ago tracing back to the fifth century yet the timing of origin of its present-day drainage is still disputed. There are two end-members of notions of the birth of the Nile, the first one believes that the present-day Nile has been connected to the Ethiopian Plateau since ~30 Ma, while the other supports the idea of young Nile around ~6 Ma. The Nile crosses today two former endorheic systems (Sudanese and Albertine “Basins”) and one exorheic system (Tethys Margin) before finally depositing sediments in the Mediterranean Sea. Our objective here focuses on deciphering the source-to-sink scenario of the Nile through relief growth, tectonic, and climate since the uppermost Cretaceous.The timing of the uplifts and deformation wavelengths are constrained by characterizing and mapping several generations of stepped pediments on DEM and satellite images which then dated using their geometrical relationships with dated magmatic rocks. Additionally, stratigraphic records of the sedimentary basins were studied to complement the dating of the pediments. The authenticity of the approaches is to integrate those data enclosing all the source-to-sink (S2S) systems to construct a coherent scenario of the Nile paleorouting systems especially on the dynamics of its sediment sources.We proposed the following model for the S2S of the Nile where its catchment grew larger southwards through time. First, a significant deformation occurred around the Cretaceous-Paleogene boundary (66 Ma) with the uplift of western limit of the Nile catchment, the Darfur-Ennedi-Tibesti domains, followed by the formation of a main large pediment. Second, this pediment was then flooded during late Paleocene (58-57 Ma) until a subtle high bounding northward the endorheic Sudanese “Basin”. Consequently, carbonate platforms were widely deposited from Paleocene until middle Eocene in the Egypt extending southwards to the former Hudi Lakes in northeast Sudan and there was no siliciclastic supply for the Nile during that time. Third, the first evidence of a fluvial system (“Pre-Eonile” according to Said, 1981) was discovered during late Eocene (~37 Ma) by large channel incisions on top of the carbonate platforms. Contemporaneously, the Uweinat Dome was uplifted and likely acted as the main siliciclastic source during late Eocene to Oligocene. Fourth, the initiation of Red Sea rifts during the Oligocene followed by a major uplift at the scale of north-east Africa (~10 Ma) provoked another plausible siliciclastic source, the Red Sea Hill’s flanks, in addition to the Uweinat Dome. Fifth, during the capture of the Sudanese endorheic system in the Early Pliocene (~4 Ma), the Nile catchment grew significantly larger and the sources were actively provided by the Darfur and Ethiopian Plateau. Finally, during middle-late Pleistocene (< 1 Ma) the Nile completed its present-day catchment by capturing the Albertine endorheic system and the siliciclastic sediments were supplied by the Ethiopian Plateau and the East African Dome.
Published: 2023

105. Diagenetic effects in Hf-Nd isotopic compositions on clay fractions: Source-to-sink analysis of signal perturbation in denudation records

Author: Camilo Esteban Gaitan, Emmanuelle Pucéat, Pierre Pellenard, Thierry Adatte, Germain Bayon, Cécile Robin, François Guillocheau, Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Institut des sciences de la terre [Lausanne] (ISTE), Université de Lausanne = University of Lausanne (UNIL), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and European Geosciences Union
Subjects: [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy
Abstract: Recent studies have coupled the Lu-Hf and Sm-Nd isotopic systems on clay fractions to assess the evolution of chemical weathering in both ancient and modern environments. Results of this proxy in the abyssal plain of the Cape Basin in Southwestern Africa show a concomitant increase of chemical weathering and physical erosion in response to a late Cretaceous tectonic uplift. In this study, we performed analyses on sediments in the continental slope of the basin that show significant differences compared to the abyssal plain: A long-steady decrease in quartz simultaneous to an increase in the calcite content during the late Cretaceous; a lower content of detrital smectite throughout the section; and the presence of mixed layer assemblages of illite – smectite (R0 or R1) and vermiculite – chlorite during the early-late Cretaceous transition, coinciding with the period of low carbonate content. First, these differences indicate a variation in the input of siliciclastic material and a change in the carbonate compensation depth. Second, clay assemblages reveal a burial diagenetic influence compared to those recorded in the abyssal domain, likely due to thicker deposition in the continental slope. These diagenetic processes indicate that there is a perturbation in the chemical weathering signal at the continental slope, therefore the disparities between the denudation record on clays in both segments cannot be attributed to an effect of signal propagation due to this post-deposition processes.
Published: 2023

106. Quantification of the damming and sediment trapping capacity of landslides and their dammed lakes: the example of the Hintersee landslide dam

Author: Anne-Laure Argentin, Thomas Hauthaler, Moritz Liebl, Jörg Robl, Stefan Hergarten, Günther Prasicek, Bernhard Salcher, Daniel Hölbling, Claire Pfalzner-Gibbon, Lisa Mandl, Michael Maroschek, Lorena Abad, Zahra Dabiri, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Paris Lodron University of Salzburg - Department of Environment and Biodiversity, University of Michigan [Ann Arbor], University of Michigan System, Institute of Earth and Environmental Sciences, Université de Lausanne = University of Lausanne (UNIL), University of Salzburg, National Park of Berchtesgaden, Partenaires INRAE, Technische Universität München = Technical University of Munich (TUM), and European Geosciences Union
Subjects: [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy
Abstract: International audience; Perennial landslide dams interrupt the sediment connectivity of rivers. Although most landslide dams do not persist for more than a few days, those that do can exhibit significant sediment trapping capacity. While water can pass through or over the dam, the sediment load is trapped upstream of the dam until the dam breaks or gradually erodes, or is completely filled with deposits. The volume of sediment stored in this way can reach up to three times the volume of impounded water, as we find by back-analyzing the lake Hintersee in southeastern Germany. In this work, we reconstruct the pre-landslide topography using Petrel and then use the Gerris shallow-water flow solver with a Voellmy rheology to back-analyze this landslide-dammed lake in the Bavarian Alps. We test several landslide release scenarios and different landslide rheologies to obtain the best-fitting reconstruction of the dam topography. We then fill the landslide dam with water and sediment using simple slope algorithms and validate the results against the current topography. Finally, we compare the landslide deposit thicknesses, water depths, and trapped sediment thicknesses of our different scenarios in order to provide new insight into the damming and sediment trapping capacity of landslides.
Published: 2023

107. Using detrital thermochronology on moraine deposits to infer glacial erosion patterns and rock thermal history : insights from the Arve and Maurienne valleys (Western European Alps)

Author: Benjamin Guillaume, Nathan Cogné, Kerry Gallagher, Pierre G. Valla, Christian Crouzet, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and European Geosciences Union
Subjects: [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry
Abstract: International audience; This study tests the application of combined detrital apatite fission track (AFT) and U-Pb dating to infer both glacial erosion spatial patterns and long-term rock cooling histories in Alpine mountainous settings. We have dated 716 detrital apatite grains from glacial sediments collected in the Maurienne and Arve valleys (Western European Alps, France) from moraine deposits corresponding to different stages of glacial retreat since the Last Glacial Maximum (LGM, ca. 24-21 ka).The Maurienne valley crosses the internal and external Alps, which exhibit contrasting in-situ AFT and U-Pb ages. Here, we present the measured distribution of both detrital AFT and U-Pb ages at 6 locations along the valley, with catchment elevations ranging from 390 to 1740 m. We show that during glacial retreat, erosion is mainly concentrated in the downstream part of the glacier, near the sampled moraine deposits. This inference suggests that during glacial retreat, glacial erosion is more effective below the ELA (Equilibrium Line Altitude) and specifically close to the glacier front, in areas where ice flow velocity is high and subglacial water is abundant, as predicted by ice-dynamics reconstructions in the European Alps over the last 20 ka.In the Arve valley, previous studies showed that in situ AFT ages are systematically younger than 7 Ma for the Mont-Blanc massif. We compare the thermal history obtained from these literature bedrock-derived data to that derived from the new detrital AFT data collected in the Little Ice Age (LIA) moraine, just at the front of the Bossons glacier (~1300 m elevation). We also compare our results with 5 other samples down the valley at catchment elevations between 460 and 1050 m to evaluate potential changes in the detrital AFT signal as well as the consistency in the retrieved long-term cooling history.Based on these first results, we plan to extend our study to other areas (e.g., Patagonia) to investigate both (1) spatial patterns of glacial erosion for older glacial periods (pre-LGM), and (2) long-term rock cooling histories from moraine deposits where modern bedrock is inaccessible (e.g. under modern glaciers or ice fields).
Published: 2023

108. Calibration of coastal hydrogeological models for the analysis of groundwater-induced flooding: from instrumentation to model reliability

Author: Martin Le Mesnil, Jean-Raynald de Dreuzy, Luc Aquilina, Frédéric Gresselin, Alexandre Gauvain, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), DREAL NORMANDIE, Direction Régionale de l'Environnement, de l'Aménagement et du Logement (DREAL), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), and European Geosciences Union
Subjects: [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract: We determine the sensitivity of groundwater-induced flooding forecast to different modelling strategies (evolving model structure and quantity/nature of data). We test three calibration strategies on shallow coastal aquifers:we use the river network as a proxy of aquifer seepage and determine uniform hydraulic conductivity and porosity. Despite limiting assumptions of surface/groundwater connections, this strategy could be broadly deployed with rapid advances in temporal and spatial river mapping at regional to national scales. we calibrate uniform conductivity and porosity on hourly piezometric data time-series close to the seashore, which are controlled by both tide and inland aquifer recharge fluctuations. We investigate the limitations of the uniform assumptions and demonstrate the interests of coastal and inland forcing as complementary sources of information. we introduce spatially variable conductivities and porosities and use additional inland piezometers. Hydraulic parameters are mapped to the main geological structures of the studied area. We analyse the results of these 3 competing strategies on the hydraulic parameters and, in a more prospective way, on the spatial distribution of vulnerabilities to groundwater fluctuations. We perform our analysis within the “Rivages Normands 2100” research project, in several sites of Western Normandy (France). In this area, low-lying coastal areas and neighbouring lands are prone to groundwater table increase, leading to flooding of buried networks and building foundations. The site of Saint-Germain-sur-Ay (66 km2 coastal watershed) is equipped with 6 piezometers from which we collected 1.5 year-long hourly time series of groundwater level. It includes a low-elevation coastal area made up of sands and a continental area made up of schists. The modelling approaches allowed us to simulate groundwater levels up to 2100, and to analyse the associated evolution of vulnerability. Simulations are performed using Modflow on a daily timestep, with a 75 m spatial resolution.Results obtained from the 3 models consistently show that vulnerable areas are mostly clustered close to the shoreline. We also show that, in the studied watershed, the first calibration strategy using the river network data leads to long-term simulations close to the second calibration strategy using the piezometric data of the coastal area. Integration of extra piezometric data from the continental area in the third strategy provides more reliable simulations. This analysis is progressively deployed to other sites and extended to cost-benefit analyses including the costs of site instrumentation and the benefits of forecast reliability. Integration of flood zones aerial photography during extreme events is being implemented to the first modelling strategy, as well as wetland mapping.
Published: 2023

109. The landscapes of southern Africa: the legacy of mantle dynamic or glacial erosion?

Author: Pierre Dietrich, François Guillocheau, Guilhem Douillet, Neil Griffis, Laurie Barrier, Daniel Le Heron, Isabel Montañez, Cécile Robin, Christoph Kettler, Axel Hofmann, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Universität Bern [Bern] (UNIBE), United States Geological Survey (USGS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), University of Vienna [Vienna], University of California [Davis] (UC Davis), University of California (UC), and European Geosciences Union
Subjects: [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology
Abstract: International audience; The modern relief of southern Africa is characterized by high-standing plateaus surrounded by escarpments and dissected by a network of encased valleys that connect the plateaus to coastal plains. This topography is commonly interpreted as resulting from the activity of a mantle plume, the African superplume, and the resulting stepwise uplift of the lithosphere, generating planation surfaces through surface erosion processes since the Mesozoic. However, in this study, we argue that part of this landscape is inherited from the glacial processes of the Late Paleozoic Icehouse (LPI) that occurred 300 ma ago and during which southern Africa was largely covered in thick ice. Field and GIS-based sedimentological and geomorphological studies however revealed that LPI glacial activity tied to the Late Paleozoic Icehouse, that occurred 300 million years ago and during which southern Africa was largely covered in thick ice, greatly contributed to the shaping of the Earth surface at different spatial scales. Glaciers levelled continental-scale planation surface, carved large valleys, fjords and overdeepenings within topographic escarpments that already existed, ploughed grooves and striae on the bedrock and left behind typical sediments such as moraines, tills and ice-contact deltas. After glacial retreat, the sea invaded these glacial reliefs, as attested by preserved paleoshorelines. In postglacial times and for 120-180 million years, these glacial landforms were progressively filled and eventually sealed under thick non-glacial sedimentary accumulation and was later rejuvenated by erosion tied to the activity of the mantle superplume. Today, large portions of the desertic high-standing plateaus, escarpments and networks of valleys defining the relief of southern Africa actually corresponds to a relict though rejuvenated 300-Ma old glacial landscape.
Published: 2023

110. Equivalent Biot and Skempton coefficients for fractured rocks&

Author: Silvia De Simone, Caroline Darcel, Hossein A. Kasani, Diego Mas Ivars, Philippe Davy, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Spanish National Research Council (CSIC), Itasca Consultants, Nuclear Waste Management Organization (NWMO), Swedish Nuclear Fuel and Waste Management Co (SKB), Royal Institute of Technology, Division of Soil and Rock Mechanics (KTH ), and European Geosciences Union
Subjects: [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract: International audience; Biot coefficient and Skempton coefficient are key descriptors of the coupled hydro-mechanical (HM) behavior of fluid-saturated porous materials. Biot coefficient defines a relationship between an applied load, fluid pressure and the stress that effectively acts on the solid skeleton. Skempton coefficient defines the temporary pore pressure variation caused by the application of a load in undrained conditions. The product of the two coefficients establishes the impact of an applied load on the solid skeleton, and thus the material deformation, under undrained conditions. The two coefficients are generally estimated through analytical expressions valid for isotropic homogeneous materials, or they are experimentally estimated at the laboratory sample-scale.In this work, we define a framework for the evaluation of equivalent Biot coefficient and Skempton coefficient at the scale of a fractured rock mass. We derive theoretical expressions that estimate the two equivalent coefficients from the properties of both the porous intact rock and the discrete fracture network (DFN), including fractures with different orientation, size, and mechanical properties. These formal expressions are validated against results from fully coupled hydro-mechanical simulations on systems with explicit representation of deformable fractures and rock blocks. We show that the coefficients largely vary with the fracture orientation and density, which implies that disregarding the presence of fractures may incur an incorrect evaluation of the HM response. We also discuss the variability of the coefficients under different settings of DFN properties, including realistic scaling conditions of size-dependent and stress-dependent fracture properties.
Published: 2023

111. 3DMASC: accessible, explainable 3D point clouds classification. Application to bi-spectral topo-bathymetric LiDAR data

Author: Mathilde Letard, Dimitri Lague, Arthur Le Guennec, Sébastien Lefevre, Baptiste Feldmann, Paul Leroy, Daniel Girardeau-Montaut, Thomas Corpetti, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Johnson and Johnson Scios, Partenaires INRAE, Littoral, Environnement, Télédétection, Géomatique (LETG - Rennes ), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Nantes Université (Nantes Univ)-Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Nantes Université (Nantes Univ), European Geosciences Union, Observation de l’environnement par imagerie complexe (OBELIX), SIGNAL, IMAGE ET LANGAGE (IRISA-D6), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Johnson & Johnson Corporation, and ARED Grant and Support from Saur Group
Subjects: multi-scale classification, feature selection, machine learning, [STAT.ML]Statistics [stat]/Machine Learning [stat.ML], [INFO.INFO-TS]Computer Science [cs]/Signal and Image Processing, multi-cloud classification, bispectral LiDAR, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, 3D data, [SDE.ES]Environmental Sciences/Environmental and Society
Abstract: Three-dimensional data have become increasingly present in earth observation over the last decades and, more recently, with the development of accessible 3D sensing technologies. However, many 3D surveys are still underexploited due to the lack of accessible and explainable automatic classification methods. In this work, we introduce explainable machine learning for 3D data classification using Multiple Attributes, Scales, and Clouds under 3DMASC, a new workflow. It handles multiple clouds at once, including or not spectral and multiple returns attributes. Through 3DMASC, we use classical 3D data multi-scale descriptors and new ones based on the spatial variations of geometrical, spectral and height-based features of the local point cloud. We also introduce dual-cloud features, encrypting local spectral and geometrical ratios and differences, which improve the interpretation of multi-cloud surveys. 3DMASC thus offers new possibilities for point cloud classification, namely for the interpretation of bi-spectral lidar data. Here, we experiment on topo-bathymetric lidar data, which are acquired using two lasers at infrared and green wavelengths, and feature two irregular point clouds characterized by different samplings of vegetated and flooded areas, that 3DMASC can harvest. By exploring the contributions of 88 features and 30 scales – including two types of neighborhoods – we identify a core set of features and scales particularly relevant for coastal and riverine scenes description, and give indications on how to build an optimal predictor vector to train 3D data classifiers. Our findings highlight the predominance of lidar return-based attributes over classical features based on dimensionality or eigenvalues, and the significant contribution of spectral information to the detection of more than a dozen of land and sea covers – artificial/vegetated/rocky/bare ground, rocky/sandy seabed, intermediate/high vegetation, buildings, vehicles, power lines. The experimental results show that 3DMASC competes with state-of-the-art methods in terms of classification performances while demanding lower complexity and thus remaining accessible to non-specialist users. Relying on a random forest algorithm, it generalizes and applies quickly to large datasets, and offers the possibility to filter out misclassified points depending on their prediction confidence. Classification accuracies between 91% for complex scene classifications and 98% for lower-level processing are observed, with average prediction confidences above 90% and models relying on less than 2000 samples per class and at most 30 descriptors – including both features and scales. Though dual-cloud features systematically outperform their single cloud equivalents, 3DMASC also performs on single cloud lidar data, or structure from motion point clouds. Our contributions are made available through a self-contained plugin in CloudCompare allowing non-specialist users to create a classifier and apply it, and an opensource labelled dataset of topo-bathymetric data.
Published: 2023

112. Impact of structural heterogeneity on solute transport and mixing in unsaturated porous media: An experimental study

Author: Oshri Borgman, Francesco Gomez, Tanguy Le Borgne, Yves Méheust, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Galilee Research Institute [Israël] (MIGAL), and European Geosciences Union
Subjects: [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract: International audience; Solute transport in unsaturated porous media plays a crucial role in soil nutrient dynamics, pesticide leaching, and contaminant migration to aquifers through the vadose zone. Natural porous media are characterized by a strong structural heterogeneity, which impacts solute spreading and mixing and the resulting chemical reaction rates. In addition, incomplete pore-scale solute mixing requires high-resolution experimental measurements to understand the system’s mixing dynamics. Our goals are to 1) study the impact of structural heterogeneity on the spatial distribution of fluid phases and 2) establish how fluid phase arrangement impacts solute spreading and mixing during unsaturated flow. We use two-dimensional porous media consisting of circular posts in a Hele-Shaw-type flow cell. The positioning of the posts is random, but we control the medium’s heterogeneity by varying the disorder in the posts’ diameters and their spatial distribution’s correlation length; increasing this length introduces more structure in the porous medium. In our experiments, we first establish an unsaturated flow pattern with a connected liquid phase and then introduce a fluorescent solute pulse transported by the moving liquid phase. We track the solute concentration and gradients’ evolution by taking periodic images of the flow cell and analyzing the fluorescence intensity field. Our results suggest that, as previously shown, decreasing the saturation degree enhances and sustains mixing rates in a disordered porous media due to the emergence of several preferential flow pathways during unsaturated flow. Moreover, increasing the solid posts’ spatial correlation reduces the number of air clusters and their interface roughness, and increases their mean size. This leads to fewer preferential flow paths during unsaturated flow for the higher correlated, more structured, porous media, compared to the less structured ones. This reduction in preferential flow paths’ number suppresses mixing rate enhancement in the more structured porous media, compared with the less structured porous media, during unsaturated flow. Our experiments show the non-trivial effect of structural heterogeneity and saturation degree on solute mixing in porous media flows. The effects demonstrated by these results are likely to affect reactive solute transport processes such as dissolution and precipitation and adsorption-controlled solute migration.
Published: 2023

113. Carbon footprint and reduction initiatives in a French geosciences laboratory

Author: Laurent Jeanneau, Emilie Jardé, Anne-Laure Argentin, Annick Battais, Thomas Bernard, Alexandre Coche, Marion Fournereau, Frédérique Moreau, Laure Guerit, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and European Geosciences Union
Subjects: [SDE]Environmental Sciences
Abstract: The impact of our productivist societies on our environment is now clearly demonstrated. It is illustrated in particular by the alteration of biogeochemical flows, the erosion of biodiversity, the chemical pollution of environments, the anthropisation of soils, the alteration of the water cycle, the acidification of the oceans and climate change.As higher education and research staff working at the interface between science and society, we are aware of the need for an environmental transition that can only be achieved by reducing our greenhouse gas emissions and our environmental impact. We do not believe that the content of our research justifies any form of exemption and are aware of the benefits of being exemplary. As a research lab, we are committed to participating in limiting the increase in the Earth's average temperature, ideally targeted at less than 1.5°C compared to the pre-industrial period. This objective requires achieving carbon neutrality by 2050.From 2021 the Sustainable Development & Social Responsibility working group of the research laboratory “Géosciences Rennes” has been created (i) to determine the C footprint by using GES1.5 (Research Consortium labo1.5), (ii) to communicate and raising staff awareness of the climate emergency, (iii) to propose indicators for reducing the carbon footprint, (iv) to convey a message to the supervisory authorities to work on the various reduction items.The calculated C footprint includes heating of buildings, electricity, purchase of goods and services, scientific missions and commutes. Between 2019 and 2021, the C footprint was 879, 520 and 708 T CO2eq, which corresponds to 5.8, 3.6 and 5.1 T CO2eq/person. The purchase of goods and services was the main item, representing 48 ± 8 % (mean ± SD) of the C footprint. Scientific missions represented 14 ± 9 % of the C footprint. Sanitary restrictions due to the covid pandemy induced a drastic decrease of the C footprint of scientific missions from 220 T CO2eq in 2019 to 43 T CO2eq in 2020.Thanks to the GES1.5 toolkit, it is possible to identify the main emission items for a given laboratory and to design and quantify specific actions to collectively reduce the C footprint. These data were the corner stone of collaborative workshops to invent our low-carbon laboratory. This presentation will feature the data and the process of collective decision in “Géosciences Rennes” laboratory. These results highlight that achieving the European Union targets will require a rethinking of the way we do science.
Published: 2023

114. Subobduction: subduction plate boundary hiccups revealed by blueschists, eclogites and ophiolites

Author: Philippe Agard, Mathieu Soret, Guillaume Bonnet, Dia Ninkabou, Alexis Plunder, Cécile Prigent, Philippe Yamato, Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and European Geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract: Fragments of ancient oceanic lithosphere preserved in mountain belts, though volumetrically subordinate, provide essential insights into past geodynamics and formation and destruction of oceanic lithosphere. This contribution shows how the two types of oceanic fragments, blueschists and eclogites, on one hand, and ophiolites on the other, preserve crucial information on the dynamics of oceanic convergence, i.e. subduction and obduction.Their mutual relationships, as well as the similarities and differences in the mechanisms leading to their preservation, allow tracking the evolution of the subduction process through time, from the onset of intra-oceanic subduction to the cessation of continental subduction – and, in some cases, to the obduction of ophiolites.Fragments located at the base and immediately below unmetamorphosed (true) ophiolites represent witnesses of intra-oceanic subduction initiation and reveal, in particular, initial mechanical resistance to subduction, subsequent cooling and gradual strain localization. Subducted fragments of oceanic lithosphere metamorphosed as blueschists and eclogites, scraped off the downgoing slab episodically, at shallow or great depths, provide direct access to the composition, structure and rheology of rocks at the plate interface.Both types reflect the mechanical behavior and 'hiccups' of the subduction plate boundary, during subduction initiation and mature subduction respectively.
Published: 2023

115. A Precipiton-Based Approach for Multi Grain-Size Transport Models

Author: Marine Le Minor, Philippe Davy, Jamie Howarth, Dimitri Lague, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Victoria University of Wellington, and European Geosciences Union
Subjects: [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph]
Abstract: Multi grain-size transport models that simulate transport of various grain sizes along with the bed stratigraphy consider that only the sediment present in an active layer at the top of the substratum participates in sediment transport. The thickness of this well-mixed layer may be fixed but also calculated according to the coarsest grain size it contains or to the shear stress applied at the surface of the substratum. However, this approach puts the emphasis on the conservation of the active layer thickness and on the availability of the various sizes within this layer. This means there is little consideration i) for heterogeneity in grain size distribution when mixing together adjacent stratigraphic layers that differ significantly in composition and ii) for grain sizes that could prevent or slow down removal of the others. To cope with these limitations, we developed an algorithm with the ability to capture the transport of heterogeneous sediments and the related stratigraphic record of erosional and depositional events based on the behavior of the various sizes within the bed layers. We built a multi grain-size module based on the precipiton method: the time spent by a precipiton (volume of water that carries sediment) on a pixel determines the grain-size specific magnitude of deposition and erosion. The newness of our work is that the magnitudes of erosion may be corrected according to the sizes that slow down the erosion of the others (zero or slow erosion rate) and stratigraphic layers with similar composition only may be merged. A few tests were conducted to study the morphological evolution of a 1D-river reach under various conditions (water discharge, sediment source, etc.). A lake was added at the end of the reach to record the various sizes existing the reach over time. At low water discharge when only the threshold of fine grains is exceeded, an armoring layer made of coarse grains develop at the surface of the substrate. At a water discharge when all the grains are in motion, the finer the grains are, the further downstream they are transported. This downstream fining pattern may be associated with changes in the concavity of the river profile. This multi grain-size algorithm not restricted to the precipiton approach has the potential to unravel the role of heterogeneous sediments in the formation of sorting patterns and, therefore, it is to be implemented in the landscape evolution model RiverLab (former Eros).
Published: 2023

116. Early Time Effective Reactivity of Reactive Transport in Cylindrically-Advected Reaction Fronts is enhanced by Hydrodynamic Dispersion

Author: Pratyaksh Karan, Uddipta Ghosh, Yves Méheust, Tanguy Le Borgne, Indian Institute of Technology [Gandhinagar] ( IIT Gandhinagar ), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and European Geosciences Union
Subjects: [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract: Reaction fronts are widespread in nature and are encountered frequently in the geological context. Examples include contaminant spread, neutralization-based reservoir decontamination, biogeochemical phenomena, and many more. The complex porous structures of subsurface formations renders the flow geometry incredibly complex, which in turn can, and often does, lead to interesting and peculiar reactive transport. For instance, the stretching and folding of the reaction front due to flow shear can enhance the effective reactivity, and flow stagnation spots can serve as sites for accummulation of reactants.At the Darcy scale, the spreading of the front is controlled by hydrodynamic dispersion, which is a continuum scale manifestation of the pore scale interaction between heterogeneous advection and molecular diffusion. When the flow field is uniform, the consequence of dispersion is only a quantitative enhancement of diffusion. However, if the flow field varies in space, as may occur for example during aquifer remediation by injection of a neutralizing agent, the effect of hydrodynamic dispersion will lead to qualitative modifications in reactive transport dynamics as compared to hypothetic scenarios where the only diffusive mechanism is molecular diffusion. Yet, despite the ubiquity of dispersion, its impact on reactive fronts in porous media has not been addressed for flows with an axisymmetrical geometry, which are typical of well injection scenarios.Therefore, we study the impact of hydrodynamic dispersion on reactive transport in cylindrically-advected bimolecular reaction fronts. We show that, in the reaction-limited regime at early times, mechanical dispersion is the dominant transport process and augments the reaction front’s advancement (which scales as t1/3, t being the time), the reaction rate (which scales as t2/3) and the product mass (which scales as t5/3), in comparison to a dispersion-free scenario (for which, the reaction front advancement, the reaction rate and the product mass scale as t1/2, t1 and t2 respectively). On the other hand, depending on the strength of hydrodynamic dispersion, we may encounter a dispersion-dominated, mixing-limited, regime of the reactive front at large times, which exhibits a declining reaction rate. This bevahior is significantly different from the dispersion-free scenario where a declining reaction rate is never encountered. Lastly, at sufficiently long times (longer for stronger dispersion), the reaction front transitions to a behavior akin to that seen in the dispersion-free scenario, wherein the differences between the dispersive and the dispersion-free scenarios become negligible.
Published: 2023

117. Convective dissolution of carbon dioxide in 2D water-saturated porous media: an experimental study in two-dimensional micromodels

Author: Niloy De, Naval Singh, Remy Fulcrand, Yves Méheust, Patrice Meunier, François Nadal, Loughborough University, Université Claude Bernard Lyon 1 (UCBL), Université de Lyon, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur les Phénomènes Hors Equilibre (IRPHE), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), CEA Cadarache, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and European Geosciences Union
Subjects: [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract: Convective dissolution is a perennial trapping mechanism of carbon dioxide in geological formations saturated with an aqueous phase. This process, which couples dissolution of supercritical CO2, convection of the liquid containing the dissolvedCO2, and mixing of the latter within the liquid, has so far not been studied in two-dimensional porous media. In order to do so, two-dimensional (2D) porous micromodels (patterned Hele-Shaw cells) have been fabricated from UV-curable NOA63 glue. NOA63 is used instead of PDMS, which is permeable to CO2 and does not allow for a controlled no flux boundary condition at the walls. The novel fabrication protocol proposed here, based on the bonding of a patterned photo-lithographed NOA63 layer on a flat NOA63 base, shows good reproducibility regardless of the pattern’s typical size, and allows for easy filling of the cell despite the small value of the gap. A pressure chamber allows pressurizing the CO2 and outside of the flow cell up to 10 bars. Experiments were performed in 11 different porous media geometries. As expected, a gravitational fingering instability is observed upon injection of gaseous carbon dioxide in the cell, resulting in the downwards migration of dissolved CO2 plumes through the 2D porous structure. The initial wavelength of the fingers is larger in the presence of a hexagonal lattice of pillars. This effect can be correctly predicted from the theory for the gravitational instability in a Hele-Shaw cell devoid of pillars, provided that the permeability of the hexagonal porous medium is considered in the theory instead of that of the Hele-Shaw cell. Fluctuations around the theoretical prediction observed in the data are mostly attributed to a hitherto unknown weak locking of the wavelength on the distance between closest pillars.
Published: 2023

118. Upper-plate shortening and Andean-type mountain-building in the context of mantle-driven oceanic subduction

Author: Robin Lacassin, Tania Habel, Anne Replumaz, Benjamin Guillaume, Martine Simoes, Thomas Geffroy, Jean-Jacques Kermarrec, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPG Paris), and European geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract: To explore the conditions that lead to mountain-building in the case of an oceanic subduction, we conduct analog experiments (with silicon putty upper and lower plates, glucose syrup upper mantle) where subduction is driven by slab pull but also by an underlying mantle flow. Here, plate displacement is not imposed as in most models, but is controlled by the overall balance of forces in the system. We simulate three scenarios: no mantle flow (slab-pull driven subduction), mantle flow directed toward the subducting plate, and mantle flow directed toward the overriding plate. In the case of this latter scenario, we also test the influence of pre-existing rheological contrasts in the upper plate to best reproduce natural cases where inheritance is common. Our experiments show that when plate convergence is also driven by a background mantle flow, the continental plate deforms with significant trench-orthogonal shortening (up to 30% after 60 Myr), generally associated with thickening. We further identify that upper plate shortening and thickening is best promoted when the mantle flow is directed toward the fixed overriding continental plate. The strength of the upper plate is also a key factor controlling the amount and rates of accommodated shortening. Deformation rates increase linearly with decreasing bulk strength of the upper plate, and deformation is mostly localized where viscosity and strength are lower. When compared to the particular natural case of the Andes, our experiments provide key insights into the geodynamic conditions that lead to the building of this Cordilleran orogen since the Late Cretaceous - Early Cenozoic.
Published: 2023

119. Determining the correct river incision mechanism under different climatic and lithological conditions using disorder metrics

Author: Marina Ruiz Sánchez-Oro, Simon M Mudd, Boris Gailleton, The University of Edinburgh, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and European Geosciences Union
Subjects: [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology
Abstract: Fluvial incision patterns help us understand the role of precipitation in river formation and evolution. Incision is generally thought to be a function of channel gradient and either discharge or drainage area. Many studies use drainage area as a proxy for discharge, but incision could potentially be related to area rather than discharge because area determines sediment fluxes. Assumptions about discharge or drainage area control on incision impact the calculations of chi profiles and steepness indices, which are indicators of the erosional and tectonic history of the landscape. Here we use numerical modelling and topographic analysis to determine if spatially varied precipitation leads to distinctive patterns of channel profiles that can be used to differentiate if a discharge or drainage-area driven incision rule is appropriate for a given landscape. We use the modelling framework Fastscape to set up two scenarios: one including an incision rule with drainage area and another with discharge (rainfall). We evolve them to steady state and extract from the resultant topography a disorder metric, which measures the relation between the tributaries and the main river in chi space. To simulate a blind test of the incision conditions, we calculate the disorder metric under the two incision case assumptions. We find that scenarios in which incision is discharge-driven cases are statistically distinguishable from those in which incision is driven by drainage area alone. We repeat these analyses with variable rainfall gradients, simulating those found in real landscapes. The results are in agreement: in a sandbox model with homogeneous lithology, it is possible to distinguish the incision case based on the disorder metric under all rainfall conditions. Real landscapes are not sandboxes, however, so we run further simulations to quantify the impact of heterogeneous lithology under different rainfall scenarios. This reveals that it is not possible to distinguish the incision case, as the distortions to channel profiles driven by lithology masks evidence of discharge dominance. We complete the analysis by testing the hypothesis in 10 real landscapes across the globe, with different lithological and climatic regimes. Some study areas, such as the Pyrénées or the Alburz Mounts, show a weak trend towards discharge dominance, although there is no conclusive statistical evidence of the preference of one incision rule, hinting at the dominance of lithology over rainfall as shown in the models.
Published: 2023

120. Chaos, Mixing, and Restart - Fluid-solid reaction enhancement under pore-scale chaotic advection

Author: Tomas Aquino, Tanguy Le Borgne, Joris Heyman, Spanish National Research Council, Barcelona, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and European Geosciences Union
Subjects: [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract: Biogeochemical reactions at the interface between fluid and solid phases are of central importance to a broad range of natural and engineered processes in porous media. As dissolved reactants are transported through a porous medium, advection and diffusion act to homogenize their concentrations, in competition with reactive depletion at the solid interface. Transport limitations can limit reactant availability, leading to reduced reaction efficiency when compared to well-mixed conditions. Chaotic advection has been recently established to occur spontaneously in steady, three-dimensional flows through porous media. In this work, we explore and quantify its role in mitigating transport limitations and correspondingly increasing reaction efficiency. We employ the continuous time random walk framework to connect reaction delays due to transport limitations to the statistics of solute excursion times to the interface. Chaotic advection is associated with a rapid loss of memory of initial conditions and efficient exploration of the bulk of the pore space. We model the corresponding effect on excursion times through a stochastic restart process, such that reactant positions are randomly restarted homogeneously across the domain over a characteristic time scale that depends on flow and geometry. Processes that restart under some condition have received much attention in the context of search strategies, where it is known that they can increase the efficiency of the underlying process. Here, we find a corresponding effect on excursion times, and a consequent increase of reaction efficiency with Péclet number. As chaotic advection leads to efficient bulk exploration, low velocities near the interface due to no-slip boundary conditions become the limiting factor on mixing and thus control the restart rate. This has the surprising consequence that, while chaotic advection sets the stage for enhanced reaction efficiency, the increase is insensitive to the "strength" of chaos as quantified by the Lyapunov exponent, and is instead controlled by flow shear at the interface. The theoretical predictions are in excellent agreement with numerical simulations of reactive decay at solid surfaces in a crystalline porous medium, over a broad range of Péclet and Damköhler numbers.
Published: 2023

121. Première campagne de fouille du tumulus de Saint-Bélec (Leuhan, Finistère)

Author: Nicolas, Clément, Pailler, Yvan, Aubry, Laurent, Freiesleben, Thrine, Galinand, Cyrille, Guérin, Guillaume, Guitton, Véronique, Hamon, Caroline, Le Gall, Bernard, Manceau, Lorraine, Munoz, Olivia, Olesen, Henrik, Onfray, Marylise, Sagory, Thomas, Seignac, Hélène, Simon-Millot, Rolande, Thomsen, Kristina, Centre National de la Recherche Scientifique (CNRS), Trajectoires - UMR 8215, Université Paris 1 Panthéon-Sorbonne (UP1)-Centre National de la Recherche Scientifique (CNRS), Université de Brest (UBO), Institut national de recherches archéologiques préventives (Inrap), Littoral, Environnement, Télédétection, Géomatique (LETG - Brest), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Nantes Université (Nantes Univ)-Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Nantes Université (Nantes Univ), Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Université Paris 1 Panthéon-Sorbonne (UP1), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Archéologie, Archéosciences, Histoire (CReAAH), Le Mans Université (UM)-Université de Rennes (UR)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Ministère de la Culture (MC)-Nantes Université - UFR Histoire, Histoire de l'Art et Archéologie (Nantes Univ - UFR HHAA), Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Geo-Ocean (GEO-OCEAN), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Musée d'Archéologie Nationale (Saint-Germain-en-Laye, FRANCE), Musée d'Archéologie Nationale, Archéologie, Terre, Histoire, Sociétés [Dijon] (ARTeHiS), Ministère de la Culture et de la Communication (MCC)-Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Ministère de la Culture, Conseil départemental du Finistère, and Nicolas, Clément
Subjects: [SHS.ARCHEO] Humanities and Social Sciences/Archaeology and Prehistory, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory
Abstract: International audience
Published: 2023

122. Poroelastic stress relaxation, slip stress transfer and friction weakening controlled post-injection seismicity at the Basel Enhanced Geothermal System

Author: Auregan Boyet, Silvia De Simone, Shemin Ge, Víctor Vilarrasa, Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), University of Colorado [Boulder], European Research Council (ERC) [801809], MCIN/AEI [CEX2018-000794-S], Spanish Government [CEX2021-001198], European Commission, and Ministerio de Ciencia e Innovación (España)
Subjects: Post-injection seismicity, [SDU]Sciences of the Universe [physics], Ensure access to affordable, reliable, sustainable and modern energy for all, General Earth and Planetary Sciences, Geothermal System, General Environmental Science
Abstract: Induced seismicity is a limiting factor for the development of Enhanced Geothermal Systems (EGS). Its causal mechanisms are not fully understood, especially those of post-injection seismicity. To better understand the mechanisms that induced seismicity in the controversial case of the Basel EGS (Switzerland), we perform coupled hydro-mechanical simulation of the plastic response of a discrete pre-existing fault network built on the basis of the monitored seismicity. Simulation results show that the faults located in the vicinity of the injection well fail during injection mainly triggered by pore pressure buildup. Poroelastic stressing, which may be stabilizing or destabilizing depending on the fault orientation, reaches further than pressure diffusion, having a greater effect on distant faults. After injection stops, poroelastic stress relaxation leads to the immediate rupture of previously stabilized faults. Shear-slip stress transfer, which also contributes to post-injection reactivation of distant faults, is enhanced in faults with slip-induced friction weakening., A.B. and V.V. acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Program through the Starting Grant GEoREST (www.georest.eu) under Grant agreement No. 801809. IDAEA-CSIC is a Centre of Excellence Severo Ochoa (Spanish Ministry of Science and Innovation, Grant CEX2018-000794-S funded by MCIN/AEI/ https://doi.org/10.13039/501100011033). This research has been carried out within the framework of the activities of the Spanish Government through the “Maria de Maeztu Centre of Excellence” accreditation to IMEDEA (CSIC-UIB) (CEX2021-001198).
Published: 2023

123. Rainfall‐induced ground deformation in southern Africa

Author: Olivier Dauteuil, Marc Jolivet, Louis Gaudaré, Anne‐Morwenn Pastier, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), Conseil National de la Recherche Scientifique, and Université de Rennes
Subjects: ground deformation, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, rainfall, Hydrology elastic flexure rainfall ground deformation, Geology, Hydrology, elastic flexure, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract: International audience; We present an analysis of ground deformation induced by large-scale seasonal rainfall in Southern Africa, based on GPS and GRACE time series and on simulations of elastic flexural response to hydrological loading. This large-scale study including South Zambia, South Angola, North Namibia and North Botswana displays a latitudinal precipitation gradient between tropical to semi-arid conditions. GRACE data display annual variations in water mass decreasing drastically southwards. GPS time series of three permanent stations located in Zambia, Namibia and Botswana show seasonal synchronous vertical displacements with amplitude decreasing southwards from 4 to 2 cm, with a shift of 2–3 months from the main rainfall season. Flexure simulations integrating rainfall, evapotranspiration, water storage, flood migration and river output produce a ground flexure up to 6 cm with timing in agreement with the GPS time series. It highlights the hydrological buffering of surface aquifer located in the Kalahari sands.
Published: 2023

124. New Cretaceous crickets of the subfamilies Nemobiinae and Podoscirtinae (Orthoptera, Grylloidea: Trigonidiidae, Oecanthidae) attest the antiquity of these clades

Author: Laure Desutter-Grandcolas, Hugo Josse, Marie Laurent, Lucas Denadai de Campos, Sylvain Hugel, Carmen Soriano, André Nel, Vincent Perrichot, Institut de Systématique, Evolution, Biodiversité (ISYEB ), Muséum national d'Histoire naturelle (MNHN)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Muséum national d'Histoire naturelle (MNHN), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Instituto de Biociencias, Departamento de Zoologia, Universidade de São Paulo = University of São Paulo (USP), Institut des Neurosciences Cellulaires et Intégratives (INCI), and Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: taxonomy, Insecta, Ensifera, amber, [SDU]Sciences of the Universe [physics], evolutionary studies, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, calibration, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, [SDV.BID.SPT]Life Sciences [q-bio]/Biodiversity/Systematics, Phylogenetics and taxonomy
Abstract: Fossils are more and more used in phylogenetic evolutionary studies either for clade calibration, or as terminals in a dataset including morphological characters. The strength of these methodological advances relies however on the quality and completeness of the fossil record. For crickets (Insecta, Orthoptera, Gryllidea), few ancient (pre-Cenozoic) well-preserved fossils are known, except for isolated wings often classified in purely fossil groups and a few fossils found in Cretaceous amber. Here, we present two remarkable fossils from mid-Cretaceous amber of France, that were imaged using X-ray synchrotron microtomography and exhibit an exquisite preservation allowing description with a precision similar to that of extant taxa. Palaeonemobius occidentalis Laurent and Desutter-Grandcolas, gen. nov., sp. nov. and Picogryllus carentonensis Josse and Desutter-Grandcolas, gen. nov., sp. nov. are the oldest representatives of the Nemobiinae and Podoscirtinae subfamilies of the Trigonidiidae and Oecanthidae families respectively. P. carentonensis Josse and Desutter-Grandcolas, gen. nov., sp. nov. is also the smallest adult male with a full stridulatory apparatus ever documented in crickets (body length 3.3 mm), and the first taxon of the cricket clade for which male genitalia can be partly described. We discuss the significance of Cretaceous fossils of crickets for future evolutionary studies of this clade.
Published: 2023

125. Sclerochronological and geochemical study of the carpet shell Ruditapes decussatus in archaeological contexts: A potential tool for season of collection and coastal paleo-temperature

Author: Marc Gosselin, Catherine Dupont, Céline Poulain, Xavier Le Coz, Grégor Marchand, Christine Paillard, Yves-Marie Paulet, François Pustoc'h, Yves Gruet, Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Archéologie, Archéosciences, Histoire (CReAAH), Le Mans Université (UM)-Université de Rennes (UR)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Ministère de la Culture (MC)-Nantes Université - UFR Histoire, Histoire de l'Art et Archéologie (Nantes Univ - UFR HHAA), Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), SMS Shell-Middens Seasonality (2017 / Leader C. Dupont), European Project: PROXARCHEOBIO, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), EPT of the European University of Brittany PROXARCHEOBIO - France (2010-2012, scientific challenges of the University of Rennes 1 « SMS Shell-Middens Seasonality, private donations, and CReAAH
Subjects: Shell Midden, Archeology, Paleo-temperature, European Atlantic coasts, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, Sclerochronology, Ruditapes decussatus, [SDE]Environmental Sciences, Seasonality, Bivalve Mollusk, Sclerochemistry, Mesolithic, [SHS]Humanities and Social Sciences
Abstract: International audience; Specimens of the carpet shell Ruditapes decussatus from the Mesolithic shell midden (6th millennium BC) of Beg-an-Dorchenn (Brittany, France) were studied in order to assess their period of collection as well as provide some insight on Paleo-temperature reconstructions. Cross sectioned shells display very clear growth structures allowing an assessment of a growth rhythm of 2 increments per lunar day. From this temporal framework, daily growth increments and winter annual growth breaks were characterized. Our results show the R. decussatus shells were typically collected in the early spring period. Chemical analyses of shell carbonates were also performed to assess a preliminary range of potential sea temperature data from oxygen isotopes values (δ18Oshell). δ18Oshell shows seasonal variations but do not record the whole seasonal temperature range as R. decussatus have a growth break during winter. However, results show predicted SSTs within the range of expected values. Thus, R. decussatus is particularly suited for paleo-environmental reconstructions at high temporal resolution such as seasonal timescales. Additional sclerochronological and chemical research on additional carpet shells and also other mollusk species from Beg-an-Dorchenn or other Mesolithic shell middens along the European Atlantic coast should be considered. Such studies will contribute to the understanding of the seasonal occupation patterns of the last hunter-gatherers of the European Atlantic coast as well as the climate variability at the Mesolithic-Neolithic transition.
Published: 2023

126. Impact of agricultural practices on veterinary pharmaceutical occurrence in superficial waters

Author: Anne Jaffrézic, Annie Soulier, Lucie Carrera, Barbara Le Bot, Emilie Jarde, Sol Agro et hydrosystème Spatialisation (SAS), Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Laboratoire d'étude et de recherche en environnement et santé (LERES), École des Hautes Études en Santé Publique [EHESP] (EHESP), Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Dubigeon, Isabelle, Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Sol Agro et hydrosystème Spatialisation ( SAS ), Institut National de la Recherche Agronomique ( INRA ) -AGROCAMPUS OUEST, Institut de recherche, santé, environnement et travail ( Irset ), Université d'Angers ( UA ) -Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -École des Hautes Études en Santé Publique [EHESP] ( EHESP ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ) -Université des Antilles ( UA ), Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), and Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS )
Subjects: [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.GC] Sciences of the Universe [physics]/Earth Sciences/Geochemistry, veterinary pharmaceutical, [SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology, farming waste, catchment, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, [ SDU.STU.GC ] Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [ SDU.STU.HY ] Sciences of the Universe [physics]/Earth Sciences/Hydrology, storm event, agriculture
Abstract: International audience; Diffuse contamination of surface water by veterinary pharmaceuticals (VP) has been poorly studied in intensive breeding context. Recycling animal waste on soil is supported to fertilize crops and reduce utilization of mineral fertilizer but may have some environmental impact by recycling pollutants on soils and transferring pollutants from soils to rivers. Most of pharmaceuticals are consumed indifferently by human and animal, especially antibiotics. This study aims to quantify veterinary pharmaceuticals (VP) in superficial water in two agricultural catchments. One is dedicated to the production of drinkable water. Agriculture but also waste water treatment plant may contribute to the contamination of water and it is difficult to distinguish animal versus human source of contamination.
Published: 2016

127. A new method of combined techniques for characterization and monitoring of seawater interface in an alluvial aquifer

Author: Folch , Albert, Del Val, Laura, Luquot, Linda, Martinez, Laura, Bellmunt, Fabian, Le Lay, Hugo, Rodellas, Valenti, Ferrer, Nuria, Fernandez, Sheila, Ledo, Juanjo, Pezard, Philippe, Bour, Olivier, Al., Et, Transferts en milieux poreux, Géosciences Montpellier, Université des Antilles et de la Guyane ( UAG ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université des Antilles et de la Guyane ( UAG ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Département de Geodinàmica I Geofísica, Universitat de Barcelona ( UB ), Université des Antilles et de la Guyane ( UAG ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), European Geosciences Union, Universitat de Barcelona (UB), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, [ SDU.STU.HY ] Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract: International audience; Understand the dynamics of the fresh-salt water interface in aquifers is a key issue to comprehend mixing processand to quantity the discharge of nutrients in to coastal areas. In order to go beyond the current knowledge inthis issue an experimental site has been set up at the alluvial aquifer Riera Argentona (Barcelona – Spain). Thesite comprises 16 shallow piezometers installed between 30 and 90 m from the seashore, with depths rangingbetween 15 and 25 meters. The seawater interface is being monitored using several techniques, the combinationof which will help us to understand the spatial and temporal behaviour of the mixing zone and the geochemicalprocesses occurring there. Specially the deepest piezometers are equipped with electrodes in order to performcross-hole electrical resistivity tomography (CHERT). In addition, all piezometers are also equipped with FiberOptic cable to perform distributed temperature measurements. Two single steel armoured fibre optic cable lines ofaround 600m length were installed in all boreholes. The objective is to use the cable both as passive and activetemperature sensor. The first is being done for the continuous monitoring of temperature whereas; the secondprovides a higher temperature resolution used to monitor field experiments.Periodic CHERT measurements are carried out between the piezometer equipped with electrodes, resultingin parallel and perpendicular vertical cross sections of the site resistivity. The position of the fresh-salt waterinterface can be identified due to the resistivity contrast between the saline and fresh water. Preliminary resultsof periodic distributed temperature measurements will be also be used to monitor the position of the mixing zonethanks to the contrast and seasonal temperature changes. Periodic down-hole EC profiles will be used to validatethe method.AcknowledgementsThis work was funded by the projects CGL2013-48869-C2-1 y CGL2013-48869-C2-2-R of the Spanish Government.We would like to thank SIMMAR (Serveis Integrals de Manteniment del Maresme) and the ConsellComarcal del Maresme in the construction of the research site
Published: 2016

128. Residence time, mineralization processes and groundwater origin within a carbonate coastal aquifer with a thick unsaturated zone

Author: Jessy Jaunat, Emilie Garel, Thierry Labasque, Hélène Celle-Jeanton, Sébastien Santoni, Frédéric Huneau, Luc Aquilina, Virginie Vergnaud-Ayraud, Sciences pour l'environnement ( SPE ), Université Pascal Paoli ( UPP ) -Centre National de la Recherche Scientifique ( CNRS ), Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Groupe d'Étude sur les Géomatériaux et Environnements Naturels, Anthropiques et Archéologiques - EA 3795 ( GEGENAA ), Université de Reims Champagne-Ardenne ( URCA ) -Institut national de recherches archéologiques préventives ( Inrap ) -SFR Condorcet, Université de Reims Champagne-Ardenne ( URCA ) -Université de Picardie Jules Verne ( UPJV ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Reims Champagne-Ardenne ( URCA ) -Université de Picardie Jules Verne ( UPJV ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Sciences pour l'environnement (SPE), Centre National de la Recherche Scientifique (CNRS)-Université Pascal Paoli (UPP), Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Groupe d'Étude sur les Géomatériaux et Environnements Naturels, Anthropiques et Archéologiques - EA 3795 (GEGENAA), Université de Reims Champagne-Ardenne (URCA)-SFR Condorcet, Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-Maison des Sciences Humaines de Champagne-Ardenne (MSH-URCA), Université de Reims Champagne-Ardenne (URCA)-Université de Reims Champagne-Ardenne (URCA), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Université Pascal Paoli (UPP)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS)-Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS)-Maison des Sciences Humaines de Champagne-Ardenne (MSH-URCA), and Laboratoire Chrono-environnement (UMR 6249) (LCE)
Subjects: Flow pattern, Coastal aquifer, Groundwater flow, 0208 environmental biotechnology, Geochemistry, Corsica, Aquifer, 02 engineering and technology, CFCs, chemistry.chemical_compound, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Vadose zone, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Groundwater discharge, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, Geomorphology, ComputingMilieux_MISCELLANEOUS, Water Science and Technology, 2. Zero hunger, geography, geography.geographical_feature_category, Hydrogeology, Residence time, [ SDU.STU.GC ] Sciences of the Universe [physics]/Earth Sciences/Geochemistry, 6. Clean water, 020801 environmental engineering, chemistry, 13. Climate action, Carbonate, Groundwater model, [ SDU.STU.HY ] Sciences of the Universe [physics]/Earth Sciences/Hydrology, Groundwater, Geology, SF6
Abstract: International audience; This study aims at establishing groundwater residence times, identifying mineralization processes and determining groundwater origins within a carbonate coastal aquifer with thick unsaturated zone and lying on a granitic depression. A multi-tracer approach (major ions, SiO2, Br-, Ba+, Sr2+, 18O, 2H, 13C, 3H, Ne, Ar) combined with a groundwater residence time determination using CFCs and SF6 allows defining the global setting of the study site. A typical mineralization conditioned by the sea sprays and the carbonate matrix helped to validate the groundwater weighted residence times from using a binary mixing model. Terrigenic SF6 excesses have been detected and quantified, which permits to identify a groundwater flow from the surrounding fractured granites towards the lower aquifer principally. The use of CFCs and SF6 as a first hydrogeological investigation tool is possible and very relevant despite the thick unsaturated zone and the hydraulic connexion with a granitic environment.
Published: 2016

129. Terrestrial plants and marine algae from the Late Jurassic lithographic limestone of the Causse Méjean (Lozère, southern France)

Author: Carmela Chateau-Smith, Gérard Lafaurie, Jean-David Moreau, Louis Baret, Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Association Paléontologique des Hauts Plateaux du Languedoc, non renseigné, adresse personnelle, UFR Sciences de la Vie, de la Terre et de l'Environnement (Université de Bourgogne) ( UFR SVTE ), Université de Bourgogne ( UB ), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), UFR Sciences de la Vie, de la Terre et de l'Environnement (Université de Bourgogne) (UFR SVTE), Université de Bourgogne (UB), Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010506 paleontology, Flora, ved/biology.organism_classification_rank.species, Late Jurassic, Context (language use), 010502 geochemistry & geophysics, 01 natural sciences, Bennettitaleans, Brachyphyllum, Paleontology, Algae, Terrestrial plant, 14. Life underwater, Pteridosperms, Dasycladales, 0105 earth and related environmental sciences, Zamites, [ SDU.STU.PG ] Sciences of the Universe [physics]/Earth Sciences/Paleontology, biology, ved/biology, Ecology, Dasyclads, lcsh:QE1-996.5, Ptéridospermes, Geology, Vegetation, 15. Life on land, biology.organism_classification, Conifères, lcsh:Geology, Conifers, Habitat, Jurassique terminal, Bennettitales, Bassin des Causses, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Causses basin
Abstract: International audience; A new Late Jurassic flora was discovered in the fossiliferous lithographic limestone of the Causse Méjean, Lozère (southern France). It consists of the first Kimmeridgian/Tithonian plants from this area. Fossil plants are represented by megaremains preserved as impressions. This flora shows a co-occurrence of terrestrial plants and marine algae. The land plants include vegetative remains ascribed to bennettitaleans (Zamites Brongniart, 1828), conifers (Brachyphyllum Brongniart, 1828), and pteridosperms (Cycadopteris Zigno, 1853). Marine algae were ascribed to dasyclads (Goniolina D’Orbigny, 1850). Lithological and palaeontological features suggest preservation in a flat, homogeneous, protected environment, perhaps a brackish or marine lagoon, influenced by both continental and marine inputs. This discovery complements the few existing reports of European Late Jurassic floras, and indicates that coastal habitats were dominated by sub-arborescent vegetation, consisting of bennettitaleans and pteridosperms, and arborescent plants, such as conifers. Both the palaeoenvironmental context and certain xerophytic features suggest that these terrestrial plants from the Causse Méjean were well adapted to the hot, dry conditions of coastal areas.; Une nouvelle flore du Jurassique terminal a été découverte dans les calcaires lithographiques du Causse Méjean,Lozère (Sud de la France). Il s’agit des tout premiers végétaux d’âge kimméridgien/tithonien provenant de ce secteur.Ces plantes fossiles sont caractérisées par des mégarestes préservés sous forme d’impressions. Cette flore montreune association de végétaux terrestres et d’algues marines : les premiers correspondent à des structures végétatives quisont attribuées à des bennettitales (Zamites BRONGNIART, 1828), des conifères (Brachyphyllum BRONGNIART, 1828), etdes ptéridospermes (Cycadopteris ZIGNO, 1853) ; alors que les secondes sont rattachées à des dasycladales (GoniolinaD’ORBIGNY, 1850). Les caractéristiques lithologiques et paléontologiques suggèrent que ces plantes ont été préservéesdans un environnement plat, homogène et protégé, telle qu’une lagune saumâtre ou marine influencée à la fois par desapports continentaux et des apports marins. Cette découverte vient compléter les quelques flores précédemment décritesdans le Jurassique terminal d’Europe. Elle suggère que les environnements côtiers étaient dominés par une végétationsub-arborescente composée de bennettitales et de ptéridospermes, puis par des plantes arborescentes comme des conifères.Le contexte paléoenvironnemental ainsi que les caractères xérophytiques présents chez les végétaux terrestres duCausse Méjean montrent que cette flore était adaptée pour tolérer les conditions chaudes et sèches des milieux côtiers.
Published: 2016

130. A better-ventilated ocean triggered by Late Cretaceous changes in continental configuration

Author: Emmanuelle Pucéat, Yannick Donnadieu, Jean-François Deconinck, François Guillocheau, Mathieu Moiroud, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Modélisation du climat (CLIM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Biogéosciences [UMR 6282] [Dijon] (BGS), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] ( LSCE ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Biogéosciences [Dijon] ( BGS ), Université de Bourgogne ( UB ) -AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique ( CNRS ), Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), and Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS )
Subjects: 010504 meteorology & atmospheric sciences, Science, Oceanic circulation, General Physics and Astronomy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Deep sea, General Biochemistry, Genetics and Molecular Biology, Article, Atmosphere, Paleontology, 14. Life underwater, 0105 earth and related environmental sciences, Multidisciplinary, [ SDU.STU ] Sciences of the Universe [physics]/Earth Sciences, General Chemistry, Anoxic waters, Cretaceous, Ocean dynamics, Indian ocean, Oceanography, 13. Climate action, Climate model, Geology
Abstract: Oceanic anoxic events (OAEs) are large-scale events of oxygen depletion in the deep ocean that happened during pre-Cenozoic periods of extreme warmth. Here, to assess the role of major continental configuration changes occurring during the Late Cretaceous on oceanic circulation modes, which in turn influence the oxygenation level of the deep ocean, we use a coupled ocean atmosphere climate model. We simulate ocean dynamics during two different time slices and compare these with existing neodymium isotope data (ɛNd). Although deep-water production in the North Pacific is continuous, the simulations at 94 and 71 Ma show a shift in southern deep-water production sites from South Pacific to South Atlantic and Indian Ocean locations. Our modelling results support the hypothesis that an intensification of southern Atlantic deep-water production and a reversal of deep-water fluxes through the Caribbean Seaway were the main causes of the decrease in ɛNd values recorded in the Atlantic and Indian deep waters during the Late Cretaceous., In the Earth's history, the timing of oceanic large-scale events of oxygen depletion remains poorly understood. Here, the authors show that palaeogeography was a major preconditioning factor during the Cretaceous, implying that thresholds to shift toward a global anoxia are likely to be much higher at present.
Published: 2016

131. Sediment provenance during Alpine orogeny: fluid inclusions and stable isotopes on quartz–calcite veins from detritic pebbles

Author: Philippe Boulvais, Michel Dubois, Véronique Gardien, Rossana Martini, Bernard Pittet, Torsten Vennemann, Anne-Sabine Grosjean, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Génie Civil et Géo-Environnement (LGCgE) - ULR 4515 (LGCgE), Université d'Artois (UA)-Université de Lille-Ecole nationale supérieure Mines-Télécom Lille Douai (IMT Lille Douai), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences [Geneva], Université de Genève = University of Geneva (UNIGE), Institut des sciences de la terre [Lausanne] (ISTE), Université de Lausanne = University of Lausanne (UNIL), Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Biogéosciences [UMR 6282] [Dijon] (BGS), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Laboratoire Génie Civil et géoEnvironnement (LGCgE) Lille Nord de France, EA 4515, Equipe Ecologie Numérique et Ecotoxicologie, Université de Lille, Sciences et Technologies, Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), University of Geneva [Switzerland], Université de Lausanne (UNIL), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Laboratoire Magmas et Volcans ( LMV ), Université Blaise Pascal - Clermont-Ferrand 2 ( UBP ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université Jean Monnet [Saint-Étienne] ( UJM ) -Centre National de la Recherche Scientifique ( CNRS ), Biogéosciences [Dijon] ( BGS ), AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] ( LGL-TPE ), École normale supérieure - Lyon ( ENS Lyon ) -Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), University of Geneva, Department of Earth Sciences, ISTE, Lausanne, and Université du Québec
Subjects: Provenance, 010504 meteorology & atmospheric sciences, Lithology, Geochemistry, Mineralogy, 010502 geochemistry & geophysics, 01 natural sciences, Petrography, Oxygen and carbon isotopes, chemistry.chemical_compound, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, ddc:550, Fluid inclusions, Water–rock interactions, Quartz, Foreland basin, 0105 earth and related environmental sciences, Calcite, Western Alps, Oligocene, Geology, [ SDU.STU.GC ] Sciences of the Universe [physics]/Earth Sciences/Geochemistry, chemistry, Isotopes of carbon
Abstract: International audience; An innovative multidisciplinary approach was used on quartz–calcite veins that crosscut pebbles of several lithologies from the French South Alpine Foreland Basin to discern the source of detrital sediments. Microthermometric results indicate that inclusions contain low to moderate salinity (0.9–9.8 wt% eq. NaCl) fluids. Oxygen and carbon isotope compositions of quartz and calcite (δ18O mean at +24.1 and +24.7 ‰ respectively (V-SMOW) and δ13C from −1.1 to +2.0 ‰ (V-PDB)) are comparable with the composition of their host rocks (δ18O from +17 to +24.3 ‰ and δ13C from −4 to +1.4 ‰). The calculated δ18O and δ13C values of the fluid trapped in quartz and calcite range from +9.3 to +21.9 ‰, and from −2.6 to +4.1 ‰ respectively. These data suggest isotopic buffering of the fluid by the host rocks. Fluid trapping conditions were 105–185 MPa and 175–310 °C. Using a lithostatic gradient, the conditions of fluid entrapment correspond to a depth of vein formation from 4 to 7 km. Petrographic and geochemical data obtained on the host rocks, their veins and fluid inclusions suggest that the source of the conglomerates is the inner part of the Alps rather than reliefs surrounding the foreland basin. The study of fluid inclusions in veins provides a powerful and innovative approach to link the production of detrital sediments with tectonic events, to trace the provenance of conglomerates and to reconstruct the regional geometry of the drainage system.
Published: 2016

132. Impact of fractures on diffusively dominated reactive transport: application to radioactive waste storage studies

Author: Delfino, Benjamin, De Dreuzy, Jean-Raynald, Erhel, Jocelyne, Cochepin, Benoit, Méheust, Yves, Fluid Flow Analysis, Description and Control from Image Sequences (FLUMINANCE), Institut de Recherche Mathématique de Rennes (IRMAR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École normale supérieure - Rennes (ENS Rennes)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-INSTITUT AGRO Agrocampus Ouest, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Agence Nationale pour la Gestion des Déchets Radioactifs (ANDRA), ANDRA, ANR-12-MONU-0012,H2MNO4,Hydrogéologie Hétérogène avec un Modèle Numérique Original, Optimisé et Orienté Objets(2012), ANR-11-LABX-0020,LEBESGUE,Centre de Mathématiques Henri Lebesgue : fondements, interactions, applications et Formation(2011), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-AGROCAMPUS OUEST-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École normale supérieure - Rennes (ENS Rennes)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Inria Rennes – Bretagne Atlantique, Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Erhel, Jocelyne, Modèles Numériques - Hydrogéologie Hétérogène avec un Modèle Numérique Original, Optimisé et Orienté Objets - - H2MNO42012 - ANR-12-MONU-0012 - MN - VALID, Fluid Flow Analysis, Description and Control from Image Sequences ( FLUMINANCE ), Institut de Recherche Mathématique de Rennes ( IRMAR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -AGROCAMPUS OUEST-École normale supérieure - Rennes ( ENS Rennes ) -Institut National de Recherche en Informatique et en Automatique ( Inria ) -Institut National des Sciences Appliquées ( INSA ) -Université de Rennes 2 ( UR2 ), Université de Rennes ( UNIV-RENNES ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture ( IRSTEA ) -Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique ( Inria ), Géosciences Rennes ( GR ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Agence Nationale pour la Gestion des Déchets Radioactifs ( ANDRA ), ANR-12-MONU-0012,H2MNO4,Hydrogéologie Hétérogène avec un Modèle Numérique Original, Optimisé et Orienté Objets ( 2012 ), Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche Mathématique de Rennes (IRMAR), AGROCAMPUS OUEST, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-École normale supérieure - Rennes (ENS Rennes)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-AGROCAMPUS OUEST, Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)
Subjects: Reac- tive transport, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Fractured network, Porous media, [ MATH.MATH-NA ] Mathematics [math]/Numerical Analysis [math.NA], [MATH.MATH-NA] Mathematics [math]/Numerical Analysis [math.NA], [ SDU.STU.GP ] Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [ INFO.INFO-DC ] Computer Science [cs]/Distributed, Parallel, and Cluster Computing [cs.DC], [INFO.INFO-DC] Computer Science [cs]/Distributed, Parallel, and Cluster Computing [cs.DC], [SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology, [SDU.STU.GP] Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [INFO.INFO-DC]Computer Science [cs]/Distributed, Parallel, and Cluster Computing [cs.DC], [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, [ SDU.STU.HY ] Sciences of the Universe [physics]/Earth Sciences/Hydrology, Radioactive waste storage, [MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA]
Abstract: International audience; Even in small numbers, fractures must be carefullyconsidered for the geological disposal of radioactivewastes. They critically enhance diusivity, speed upsolute transport, extend mixing fronts and, in turn,modify the physicochemical conditions of reactivityaround possible storage sites. Fractures occur at se-veral places in the cement surrounding the containersand in the Excavation Damaged Zones (EDZ) of thegalleries. They even occur in clays like in the FrenchCallovo-Oxfordian formation mostly because of the de-saturation conditions induced in the operational timeof the galleries.Numerous studies in various elds (e.g. radioactivewaste storage, CO2 sequestration, geothermal storage,hydrothermal alteration) have shown that fracturescannot be simply integrated within an equivalent po-rous medium with a simple enhancement of its petro-physical properties (porosity and permeability). Frac-tures cannot either be accurately identied and fullydeterministic modeling approaches are precluded.We propose a combined numerical and experimentalapproach to determine the influence on reactivity oftypical fracture patterns classically found in radioac-tive waste applications. We investigate the possibilityto apply simplied modeling frameworks on the basisof some key properties :(i) transport is mostly diusive and much faster inthe fractures than in the porous matrix [1],(ii) reactivity occurs predominantly in the matrix be-cause of the large surface to volume ratio favorableto dissolution/precipitation processes,(iii) reactivity within the surrounding matrix is atequilibrium, or equivalently much faster thanthe diusive transport. Reactivity is assumedtransport-limited rather than rate-limited.Based on the separation of the fracture and ma-trix domains, we develop a reactive transport mo-del with diering diusion conditions in the fractureand in the matrix, appropriate flow-rock interactionsat equilibrium in the matrix and fracture-matrix ex-change conditions at their interface. Using preferen-tially existing software, we propose simulation methodsthat comply with much faster diusion in the fracturethan in the matrix, and validate them against elemen-tary fracture structures and simplied reactivity.We intend to use the developed methods on dierentfracture structures to simulation reactivity over longperiods of time. We determine the possible relevanceof the most classical simplied frameworks for fracture-matrix including :(i) fully homogenized models with adapted porosity,permeability and surface to volume ratio to reco-ver localization eects,(ii) models with isolated fractures within "innite ma-trix" assuming implicitly the localization of reac-tivity in the immediate vicinity of the fracture [2],(iii) double porosity models characterized by single ormultiple exchange coecients[3].Following the outcome of the numerical simulations,we will investigate experimentally the most critical li-mitation of reactivity. It might a priori be either thefracture to matrix exchange law especially if fractureis desaturated and matrix saturated.Within the radioactive waste framework, we aim atincluding fractures in the safety assessment workflow.We intend to determine to which extent fractures faci-litate the access to reactive surfaces, the increase of thebulk reactivity, the corrosion potential and the pertur-bation of the chemical conditions.We frame as much aspossible the reference simulations in realistic physicaland chemical conditions including the main operatio-nal phases of the radioactive waste repository. Resultswill be reported as comprehensive evolution scenarios.References[1] D. Roubinet, J. R. Dreuzy, and D. M. Tartakovsky.Semi-analytical solutions for solute transport and ex-change in fractured porous media. Water ResourcesResearch, 48(1), 2012.[2] C. I. Steefel and P. C. Lichtner. Multicomponent reac-tive transport in discrete fractures : I. controls on reac-tion front geometry. Journal of Hydrology, 209(1) :186{199, 1998.[3] T. Xu and K. Pruess. Modeling multiphase non-isothermal fluid flow and reactive geochemical transportin variably saturated fractured rocks : 1. methodology.American Journal of Science, 301(1) :16{33, 2001.
Published: 2016

133. Fossiliferous Holocene tufa of Mende (Lozère, southern France): implication for the Atlantic vegetation of the Causses Basin

Author: Vincent Trincal, Anne-Véronique Walter-Simonnet, Benjamin Bourel, Jean-David Moreau, Association Paléontologique des Hauts Plateaux du Languedoc, non renseigné, Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), and Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE)
Subjects: 010506 paleontology, Leaves, Angiosperms, 010504 meteorology & atmospheric sciences, Tilia cordata, Structural basin, 01 natural sciences, Tufs, law.invention, Feuilles, Paleontology, Lozère, law, Radiocarbon dating, Causses Basin, Holocene, 0105 earth and related environmental sciences, [ SDU.STU.PG ] Sciences of the Universe [physics]/Earth Sciences/Paleontology, geography, geography.geographical_feature_category, Bassin des Causses, biology, lcsh:QE1-996.5, Geology, Vegetation, Tufas, biology.organism_classification, Karst, lcsh:Geology, Tufa, Angiospermes, Quaternary, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Holocène
Abstract: International audience; Tufas bearing plant macroremains are uncommon in the Causses Basin (southern France). Here, we report anew fossiliferous tufa deposits at Mende, in Lozère. This palaeontological site is the first Quaternary tufa from thenorthern part of the Causses Basin that yields such an abundance of plant macroremains. The radiocarbon dating showsthat these Holocene deposits are related to the Atlantic period. Geomorphology and mineralogy show that theplant-bearing deposit is a calcareous tufa only composed by calcite, deposited near to an outlet of cool water, linked tothe karstic hydrological system of the Causse de Mende. The flora exposed in this article is dominated by angiosperms.Leaves and reproductive structures were assigned to Acer platanoides, Corylus sp., Hedera sp., Salix cf. cinerea, andTilia cordata. This new palaeobotanical data complements our scarcely knowledge of the Atlantic floras from the CaussesBasin. During the Atlantic period, and in the northern part of the basin, whereas Pinus-dominated forests and oakgroves were probably well-developed, valleys were locally inhabited by diversified wet angiosperm-dominated forests.; Les tufs livrant des macrorestes végétaux sont peu fréquents dans le Bassin des Causses (sud de la France).Nous présentons ici un tuf fossilifère inédit, à Mende, en Lozère. Ce site paléontologique est le premier tuf quaternairede la partie nord du Bassin des Causses à livrer une telle richesse en macrorestes de plantes. La datation radiocarbonedémontre que les dépôts sont d’âge holocène, plus particulièrement de la période Atlantique. La géomorphologie et laminéralogie montrent que le niveau à plantes est un tuf calcaire exclusivement composé de calcite, déposé à proximitéd’une source d’eau fraîche reliée au système hydrologique karstique du Causse de Mende. La flore présentée dans cetarticle est dominée par des angiospermes. Les feuilles et les structures reproductrices sont attribuées à Acer platanoides,Corylus sp., Hedera sp., Salix cf. cinerea, and Tilia cordata. Ces nouvelles données paléobotaniques complètent notreconnaissance encore partielle des flores de l’Atlantique, dans le Bassin des Causses. Cette étude soutient que pendantl’Atlantique, et dans la partie nord du bassin, alors que les forêts de pins et de chênes étaient probablement dominantes,les vallées caussenardes étaient localement habitées par des forêts plus humides, riches en angiospermes.
Published: 2016

134. Strontium isotopes as tracers of water-rocks interactions, mixing processes and residence time indicator of groundwater within the granite-carbonate coastal aquifer of Bonifacio (Corsica, France)

Author: Emilie Garel, Hélène Celle-Jeanton, Luc Aquilina, Thierry Labasque, Frédéric Huneau, Virginie Vergnaud-Ayraud, Sébastien Santoni, Sciences pour l'environnement ( SPE ), Université Pascal Paoli ( UPP ) -Centre National de la Recherche Scientifique ( CNRS ), Géosciences hydrosciences matériaux constructions ( Ghymac ), Université Sciences et Technologies - Bordeaux 1, Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Université européenne de Bretagne ( UEB ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Sciences pour l'environnement (SPE), Centre National de la Recherche Scientifique (CNRS)-Université Pascal Paoli (UPP), Géosciences hydrosciences matériaux constructions (Ghymac), Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Université européenne de Bretagne - European University of Brittany (UEB), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Université Pascal Paoli (UPP)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and Laboratoire Chrono-environnement (UMR 6249) (LCE)
Subjects: Environmental Engineering, 0208 environmental biotechnology, Geochemistry, Corsica, Weathering, Aquifer, 02 engineering and technology, 010501 environmental sciences, 01 natural sciences, chemistry.chemical_compound, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Environmental Chemistry, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, Hydrogeochemistry, Waste Management and Disposal, 0105 earth and related environmental sciences, Hydrology, geography, geography.geographical_feature_category, Water-rocks interaction, Sediment, Groundwater recharge, Strontium isotopes, [ SDU.STU.GC ] Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Pollution, 020801 environmental engineering, Calcarenite, Kinetics, chemistry, 13. Climate action, Carbonate, Sedimentary rock, [ SDU.STU.HY ] Sciences of the Universe [physics]/Earth Sciences/Hydrology, Groundwater, Geology
Abstract: This study aims at identifying the water-rock interactions and mixing rates within a complex granite-carbonate coastal aquifer under high touristic pressure. Investigations have been carried out within the coastal aquifer of Bonifacio (southern Corsica, France) mainly composed of continental granitic weathering products and marine calcarenite sediments filling a granitic depression. A multi-tracer approach combining physico-chemical parameters, major ions, selected trace elements, stable isotopes of the water molecule and 87Sr/86Sr ratios measurements is undertaken for 20 groundwater samples during the low water period in November 2014. 5 rock samples of the sedimentary deposits and surrounding granites are also analysed. First, the water-rock interactions processes governing the groundwater mineralization are described in order to fix the hydrogeochemical background. Secondly, the flow conditions are refined through the quantification of inter aquifer levels mixing, and thirdly, the kinetics of water-rock interaction based on groundwater residence time from a previous study using CFCs and SF6 are quantified for the two main flow lines. A regional contrast in the groundwater recharge altitude allowed the oxygene-18 to be useful combinedwith the 87Sr/86Sr ratios to differentiate the groundwater origins and to compute the mixing rates, revealing the real extension of the watershed and the availability of the resource. The results also highlight a very good correlation between the groundwater residence time and the spatial evolution of 87Sr/86Sr ratios, allowingwater-rock interaction kinetics to be defined empirically for the two main flowlines through the calcarenites. These results demonstrate the efficiency of strontiumisotopes as tracers of water-rock interaction kinetics and by extension their relevance as a proxy of groundwater residence time, fundamental parameter documenting the long term sustainability of the hydrosystem.
Published: 2016

135. Lateral diffusivity coefficients from the dynamics of a SF6 patch in a coastal environment

Author: T. Labasque, Anne Petrenko, Andrea Doglioli, Jerome Bouffard, Stéphane Blain, Francesco Nencioli, Frédéric Diaz, Bernard Quéguiner, Marion Kersale, Ivan Dekeyser, Laboratoire de physique des océans ( LPO ), Institut de Recherche pour le Développement ( IRD ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ), Institut méditerranéen d'océanologie ( MIO ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Toulon ( UTLN ) -Aix Marseille Université ( AMU ) -Institut de Recherche pour le Développement ( IRD ), Plymouth Marine Laboratory ( PML ), Plymouth Marine Laboratory, Laboratoire d'Océanographie Microbienne ( LOMIC ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Plymouth Marine Laboratory (PML), Laboratoire d'Océanographie Microbienne (LOMIC), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), CNRS/INSU-Institut National des Sciences de l'Univers, Region PACA-Provence Alpes Côte d'Azur, FP7-PEOPLE-IEF-2011, FP7 Marie Curie Actions of the European Commission, MENRT Ph.D. Grant, Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)
Subjects: 010504 meteorology & atmospheric sciences, Mass diffusivity, Aquatic Science, Oceanography, Thermal diffusivity, Atmospheric sciences, 01 natural sciences, Lateral diffusivity coefficient, Atmosphere, Mediterranean sea, TRACER, SF 6 tracer, [CHIM]Chemical Sciences, 14. Life underwater, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, Dispersion (water waves), Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Hydrology, [ SDU.STU.OC ] Sciences of the Universe [physics]/Earth Sciences/Oceanography, 010505 oceanography, Front (oceanography), Lagrangian referential, Sea surface temperature, 13. Climate action, Coastal area, SF6 tracer, Geology
Abstract: International audience; The dispersion of a patch of the tracer sulfur hexafluoride (SF 6) is used to assess the lateral diffusivity in the coastal waters of the western part of the Gulf of Lion (GoL), northwestern Mediterranean Sea, during the Latex10 experiment (September 2010). Immediately after the release, the spreading of the patch is associated with a strong decrease of the SF 6 concentrations due to the gas exchange from the ocean to the atmosphere. This has been accurately quantified, evidencing the impact of the strong wind conditions during the first days of this campaign. Few days after the release, as the atmospheric loss of SF 6 decreased, lateral diffusivity coefficient at spatial scales of 10 km has been computed using two approaches. First, the evolution of the patch with time was combined with a diffusion–strain model to obtain estimates of the strain rate (γ = 2.510 −6 s −1) and of the lateral diffusivity coefficient (K h = 23.2 m 2 s −1). Second, a steady state model was applied, showing K h values similar to the previous method after a period of adjustment between 2 and 4.5 days. This implies that after such period, our computation of K h becomes insensitive to the inclusion of further straining of the patch. Analysis of sea surface temperature satellite imagery shows the presence of a strong front in the study area. The front clearly affected the dynamics within the region and thus the temporal evolution of the patch. Our results are consistent with previous studies in open ocean and demonstrate the success and feasibility of those methods also under small-scale, rapidly-evolving dynamics typical of coastal environments.
Published: 2016

136. Guide des ammonites pyriteuses, Toarcien moyen et supérieur des Causses (Lozère - France)

Author: Romain Jattiot, Vincent Trincal, Jean-David Moreau, André Brocard, Paläontologisches Institut und Museum, Universität Zürich [Zürich] ( UZH ), TCS, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ) -Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Lille, Sciences Humaines et Sociales, Universität Zürich [Zürich] = University of Zurich (UZH), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), University of Zurich, Trincal, Vincent, Laboratoire Chrono-environnement (UMR 6249) (LCE), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 560 Fossils & prehistoric life, Lozère, Toarcien, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, Ammonite, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [ SDU.STU ] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU.PG] Sciences of the Universe [physics]/Earth Sciences/Paleontology, Toarcian, pyriteuse, 10125 Paleontological Institute and Museum, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, [ SDU.STU.PG ] Sciences of the Universe [physics]/Earth Sciences/Paleontology
Abstract: Hammatoceras, Harpoceras, Hildoceras, Lytoceras, Phylloceras… autant de noms d’ammonites qui vous paraissent peut-être étrangers ? Grace à ce manuel, apprenez à les reconnaître, afin d’apprécier la diversité de ces animaux qui peuplaient les fonds marins du Jurassique, il y a 180 millions d’années. Avec 29 genres et 80 espèces représentés, ainsi que quelques ammonites pathologiques, cette synthèse, richement illustrée, vous permettra d’avoir un œil expert sur les ammonites pyriteuses françaises (lozériennes ou non) du Toarcien moyen et supérieur. Ce guide d’identification organisé sous forme de fiches se veut simple d’utilisation afin de vous offrir la possibilité d’identifier vos découvertes en deux étapes. (1) Une clé de détermination à l’échelle du genre permet de débuter l’identification et de sélectionner rapidement les genres auxquels pourraient appartenir votre spécimen. (2) Il suffit ensuite de se référer aux fiches espèces appartenant aux genres retenus. Pour chaque fiche espèce, vous trouverez les caractéristiques propres à l’espèce mais, aussi et surtout, des critères clairement exposés permettant de la distinguer des autres espèces ressemblantes.En plus d’être un inventaire des espèces d’ammonites pyriteuses identifiées dans le secteur de Cénaret, à Barjac, ce livre se veut donc être un véritable outil de détermination didactique qui, espérons-le, ne vous quittera plus lors de vos prospections...Avec ce guide (et un carte géologique de la région), partez en prospection à la découverte des restes fossiles de ces animaux marins disparus !
Published: 2015

137. USING BISPECTRAL FULL-WAVEFORM LIDAR TO MAP SEAMLESS COASTAL HABITATS IN 3D

Author: M. Letard, A. Collin, D. Lague, T. Corpetti, Y. Pastol, A. Ekelund, École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Littoral, Environnement, Télédétection, Géomatique (LETG - Rennes ), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Nantes Université (Nantes Univ)-Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Nantes Université (Nantes Univ), Service Hydrographique et Océanographique de la Marine (SHOM), Ministère de la Défense, Airborne Hydrography AB - Jönköping, Saur Group, Région Bretagne ARED program, and Nantes-Rennes topo-bathymetric lidar platform.
Subjects: Habitat mapping, Topobathymetric lidar, Full-waveform lidar, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Classification, Coastal habitats
Abstract: Mapping coastal habitats is essential to their preservation, but the presence of water hinders seamless data collection over land-water interfaces. Thanks to its dual-wavelength and optical properties, topo-bathymetric lidar can address this task efficiently. Topo-bathymetric lidar waveforms contain relevant information to classify land and water covers automatically but are rarely analysed for both infrared and green wavelengths. The present study introduces a point-based approach for the classification of coastal habitats using bispectral waveforms of topo-bathymetric lidar surveys and machine learning. Spectral features and differential elevations are fed to a random forest algorithm to produce three-dimensional classified point clouds of 17 land and sea covers. The resulting map reaches an overall accuracy of 86%, and 65% of the prediction probabilities are above 0.60. Using this prediction confidence, it is possible to map coastal habitats and eliminate the classification errors due to noise in the data, that generate a clear tendency of the algorithm to over-estimate some classes at the expense of some others. By filtering out points with a low prediction confidence (under 0.7), the classification can be highly improved and reach an overall accuracy of 97%.
Published: 2022

138. Reconsidering Carboniferous–Permian continental paleoenvironments in eastern equatorial Pangea: facies and sequence stratigraphy investigations in the Autun Basin (France)

Author: Mathilde Mercuzot, Sylvie Bourquin, Pierre Pellenard, Laurent Beccaletto, Johann Schnyder, François Baudin, Céline Ducassou, Sylvain Garel, Georges Gand, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of Utah, Région Bretagne, and Bureau de Recherches Géologiques et Minières (BRGM)
Subjects: Late-Variscan basin, Gzhelian, Paleogeography, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, General Earth and Planetary Sciences, Continental delta environments, Asselian, Paleoenvironment
Abstract: International audience; The late Carboniferous–early Permian represents a key period in the Phanerozoic history, given the major global geodynamic and climate modifications. The aim of this work is to better understand the context and characteristics of the sedimentation recorded in the continental environments of eastern equatorial Pangea at this time, through the example of the Autun Basin (northeastern Massif Central, France). The Autun Basin contains the historical stratotype of the Autunian continental stage, and its stratigraphy was recently improved by accurate numerical ages. This basin formed in an extensional tectonic context during the latest stages of the Variscan orogeny, and it is essential to study its paleoenvironmental evolution to provide new insights into the sedimentary evolution of contemporaneous surrounding basins. Using field and subsurface data, we propose a refined sedimentological model for the Autun Basin, relying on updated facies interpretations, organic matter content fluctuations, and sequence stratigraphy concepts and correlations. The continental environments of the lower sedimentary succession of the Autun Basin, previously considered to be fluvial and lacustrine, are herein re-interpreted as mainly lacustrine, comprising fine-grained organic matter-rich deposits, and supplied by coarser-grained deltaic siliciclastic sediments, without preservation of strict fluvial sedimentation. The determination of the sequence stratigraphy cycles, strengthened by the quantification of the organic matter content, and reflected by the temporal succession of progradational and retrogradational trends, is used to determine new correlations between several sections, as well as to reconstruct the paleoenvironment evolution at the Carboniferous–Permian transition. This study provides evidence that the sedimentation area of the Autun Basin at the time of its filling was much larger than the preserved basin area, and suggests connections with contemporaneous neighboring French basins, pointing to a large sedimentary system in the northeastern Massif Central area rather than narrow and isolated basins.
Published: 2022

139. Neogene South Asian monsoon rainfall and wind histories diverged due to topographic effects

Author: Anta-Clarisse Sarr, Yannick Donnadieu, Clara T. Bolton, Jean-Baptiste Ladant, Alexis Licht, Frédéric Fluteau, Marie Laugié, Delphine Tardif, Guillaume Dupont-Nivet, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), University of Potsdam = Universität Potsdam, and ANR-16-CE31-0020,AMOR,Reconstruction modèle-données des climats du Cénozoique(2016)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Palaeoceanography, General Earth and Planetary Sciences, Palaeoclimate, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract: International audience; The drivers of the evolution of the South Asian Monsoon remain widely debated. An intensification of monsoonal rainfall recorded in terrestrial and marine sediment archives from the earliest Miocene (23–20 million years ago (Ma)) is generally attributed to Himalayan uplift. However, Indian Ocean palaeorecords place the onset of a strong monsoon around 13 Ma, linked to strengthening of the southwesterly winds of the Somali Jet that also force Arabian Sea upwelling. Here we reconcile these divergent records using Earth system model simulations to evaluate the interactions between palaeogeography and ocean–atmosphere dynamics. We show that factors forcing the South Asian Monsoon circulation versus rainfall are decoupled and diachronous. Himalayan and Tibetan Plateau topography predominantly controlled early Miocene rainfall patterns, with limited impact on ocean–atmosphere circulation. The uplift of the East African and Middle Eastern topography played a pivotal role in the establishment of the modern Somali Jet structure above the western Indian Ocean, while strong upwelling initiated as a direct consequence of the emergence of the Arabian Peninsula and the onset of modern-like atmospheric circulation. Our results emphasize that although elevated rainfall seasonality was probably a persistent feature since the India–Asia collision in the Paleogene, modern-like monsoonal atmospheric circulation only emerged in the late Neogene.
Published: 2022

140. Boris Choubert: Unrecognized visionary geologist, pioneer of the global tectonics

Author: Philippe Le Vigouroux, Anne-Marie Boullier, Dominik Letsch, Umberto G. Cordani, Benito Ábalos, Brian Upton, Jacques Kornprobst, Åke Johansson, Pierre Barbey, Roy H. Gabrielsen, Jean-Pierre Burg, José Ignacio Gil-Ibarguchi, David Corrigan, Stefan Claesson, Ramon Capdevila, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Swedish Museum of Natural History (NRM), Universidade de São Paulo = University of São Paulo (USP), Geological Survey of Canada [Ottawa] (GSC Central & Northern Canada), Geological Survey of Canada - Office (GSC), Natural Resources Canada (NRCan)-Natural Resources Canada (NRCan), Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Comité français d'histoire de la géologie (COFRHIGEO), Centre François Viète : épistémologie, histoire des sciences et des techniques - EA1161 (CFV), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Université de Brest (UBO)-Université de Nantes - UFR Lettres et Langages (UFRLL), Université de Nantes (UN)-Université de Nantes (UN), Grant Institute, University of Edinburgh, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Universidade de São Paulo (USP), Université de Nantes (UN)-Université de Brest (UBO), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), Université de Lorraine (UL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans ( LMV ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université Jean Monnet [Saint-Étienne] ( UJM ) -Institut de Recherche pour le Développement et la société-Université Clermont Auvergne ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), Centre de Recherches Pétrographiques et Géochimiques ( CRPG ), Université de Lorraine ( UL ) -Centre National de la Recherche Scientifique ( CNRS ), Institut des Sciences de la Terre ( ISTerre ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux ( IFSTTAR ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc ( USMB [Université de Savoie] [Université de Chambéry] ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ), Eidgenössische Technische Hochschule [Zürich] ( ETH Zürich ), Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique ( CNRS ), Swedish Museum of Natural History, Stockholm, Department of Geosciences, University of Oslo ( UiO ), Comité français d'histoire de la géologie ( COFRHIGEO ), Centre François Viète : épistémologie, histoire des sciences et des techniques, and Université de Nantes ( UN ) -Université de Brest ( UBO )
Subjects: Pangaea, PRÉ-CAMBRIANO, 010504 meteorology & atmospheric sciences, Paleozoic, 010502 geochemistry & geophysics, 01 natural sciences, tectonique des plaques, [SHS.HISPHILSO]Humanities and Social Sciences/History, Philosophy and Sociology of Sciences, Precambrian, Paleontology, dérive continentale, orogeny, ComputingMilieux_MISCELLANEOUS, [ SDU.STU.PE ] Sciences of the Universe [physics]/Earth Sciences/Petrography, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Wegener, lcsh:QE1-996.5, Précambrien, Geology, Orogeny, orogenèse, lcsh:Geology, Plate tectonics, Tectonics, Continental drift, Palaeozoic belts, Dérive continentale, Tectonique des plaques, Orogenèse, 13. Climate action, plate tectonics, continental drift, Geologist
Abstract: This work is a review of Boris Choubert’s paper (1935), which was published in French under the rather devalorizing title: “Research on the Genesis of Palaeozoic and Precambrian Belts.” Despite its innovative content, this article had no impact either at the time of its publication or even later. It begins with the construction of a remarkable fit of the circum-Atlantic continents. This was based on the −1.000 meters isobath instead of the shoreline. Thirty years before Bullard et al. (1965), it demonstrated in an indisputable way the reality of the continents motion on the surface of the Earth. Therefore, Choubert designated Wegener’s “continental drift” as the main cause of tectonics. Even going beyond Wegener’s theory, he argued that this mechanism was efficient well before the formation of the Triassic Pangæa, during the whole Palaeozoic to result in the building of the Caledonian and Hercynian mountains. Although he was still encumbered by the vocabulary of the time regarding geosynclines, Boris Choubert described tectonics based on the horizontal mobility of the Precambrian continental blocks. Oddly enough, he did not apply this model to the Precambrian structures, which he attributed to the effects of the Earth’s rotation on the continental crust during its solidification. At the time of its publication, this paper was a very important step towards understanding global tectonics. Unfortunately, Choubert’s contemporaries did not generally recognize its significance. Ce travail est une analyse de l’article de Boris Choubert (1935) paru en français sous le titre un peu réducteur: « Recherches sur la genèse des chaînes paléozoïques et antécambriennes. » Malgré son contenu novateur, cet article n’a eu aucun retentissement à l’époque de sa publication, ni même plus tard. Il débute par la construction d’un remarquable assemblage des continents péri-atlantiques fondé sur l’isobathe −1.000 mètres et non pas sur la ligne de rivage. Trente ans avant Bullard et al. (1965), il démontre de façon indiscutable la réalité du déplacement des masses continentales à la surface de la Terre. Dès lors, Choubert privilégie totalement la « dérive des continents » comme moteur de la tectonique. Allant au-delà même de la vision de Wegener, il fait jouer ce mécanisme bien avant la formation de la Pangée triasique, pendant toute la durée de l’ère primaire, au cours de l’érection des chaînes calédonienne et hercynienne. Bien que restant prisonnier du vocabulaire de l’époque sur les géosynclinaux, Boris Choubert décrit une tectonique fondée sur la mobilité des blocs continentaux précambriens. Curieusement, il n’applique pas ce modèle aux déformations précambriennes qu’il attribue aux effets de la rotation de la Terre sur une croûte continentale en voie de solidification. Lors de sa parution, cet article représentait un pas très important vers la compréhension de la tectonique globale et il est regrettable qu’il n’ait pas été mieux reçu par ses contemporains. ISSN:0037-9409 ISSN:1777-5817
Published: 2018

141. Cranial morphology and phylogenetic relationships of Amynodontidae Scott & Osborn, 1883 (Perissodactyla, Rhinocerotoidea)

Author: Léa VEINE-TONIZZO, Jérémy TISSIER, Maia BUKHSIANIDZE, Davit VASILYAN, Damien BECKER, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Carleton University, Canadian Museum of Nature (CANADA), Jurassica Museum, American Museum of Natural History (AMNH), Georgian National Museum, Université de Fribourg = University of Fribourg (UNIFR), and Swiss National Science Foundation (SNF) [200021_162359, P2FRP2_199605]
Subjects: skull, Rhinocerotoidea, [SDU]Sciences of the Universe [physics], Zaisanamynodon, Oligocene, Paleontology, Amynodontidae, Metamynodon, Big Badlands, phylogeny, Eocene, Zaysan Basin
Abstract: Les Amynodontidae Scott& Osborn, 1883 sont une famille éteinte de Rhinocerotoidea Owen, 1845 connue depuis l’Éocène moyen jusqu’à la fin de l’Oligocène en Asie, en Amérique du Nord et en Europe. Nous présentons ici deux spécimens inédits d’Amynodontidae, un crâne et une mandibule, de Zaisanamynodon borisovi Belyaeva, 1971, datés de la fin de l’Éocène du bassin de Zaïssan (Kazakhstan) et un crâne de Metamynodon planifrons Scott& Osborn, 1887, daté du début de l’Oligocène des Big Badlands (États-Unis). Ce nouveau matériel a été inclus dans une matrice de caractères morpho-anatomiques. Elle a été complétée par le codage de l’espèce récemment décrite Amynodontopsis jiyuanensis Wang X.-Y., Wang Y.-Q., Zhang R., Zhang Z.-H., Liu & Ren, 2020 et les codages révisés de Cadurcotherium cayluxi Gervais, 1873 et Cadurcotherium minum Filhol, 1880. Nous avons réalisé une analyse cladistique basée sur cette matrice, incluant 31 taxons terminaux de Rhinocerotoidea. La nouvelle hypothèse phylogénétique proposée permet de discuter des positions phylogénétiques des spécimens étudiés au sein des Amynodontidae et de la position des Amynodontidae au sein des Rhinocerotoidea. Notre analyse cladistique clarifie la composition générique et spécifique des tribus Metamynodontini Kretzoi, 1942 et Cadurcodontini Wall, 1982 et soutient la monophylie de Zaisanamynodon Belyaeva, 1971. La dichotomie des deux tribus s’exprime notamment par la présence de plusieurs caractéristiques crâniennes telles que “l’allongement de l’incisure nasale” ou “la fosse préorbitaire bien développée” chez les Cadurcodontini. Ces spécialisations témoignent d’une adaptation de la région péri-nasale à la présence d’un proboscis. Notre étude ouvre également une discussion sur la biogéographie des Amynodontidae, leur émergence et dispersion en Asie à l’Éocène moyen puis leur colonisation de l’Amérique du Nord et de l’Europe de l’Est. Leur présence en Europe occidentale est, quant à elle, restreinte à l’Oligocène et liée à l’événement de la Grande Coupure.
Published: 2023

142. Crustacés (Crustacea, Decapoda) du Jurassique moyen de Normandie, France

Author: Chény, Cédric, Charbonnier, Sylvain, Audo, Denis, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Paléontologie - Paris (CR2P), and Muséum national d'Histoire naturelle (MNHN)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Longodromitidae, Arthropoda, Callovian, Eryma, Paleontology, Geology, Callovien, Biodiversity, Abyssophtalmus, Decapoda, Animalia, Glypheidae, conservation exceptionnelle, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Malacostraca, Erymidae, Taxonomy
Abstract: International audience; The Middle Jurassic (Callovian) fauna from Sainte-Scolasse-sur-Sarthe (Normandy, France) is remarkable for its exceptionally preserved crustaceans in arenaceous limestone beds. The crustacean fauna includes five species assigned to the Glypheidae, Erymidae and Longodromitidae. Glypheid lobsters are the most diversified and abundant group. A new detailed anatomic description leads to the first reconstruction of Glyphea dressieri Meyer in Bronn, 1837, and to highlight a marked sexual dimorphism. Similar observations are made in Glyphea regleyana (Desmarest, 1822). A quantitative analysis based on 149 specimens shows two dominant species: Glyphea regleyana (47.0 % of specimens) and G. dressieri (46.3 %). The palaeoenvironment is interpreted as subtidal mud flats largely open to offshore conditions. More precisely, the sedimentary facies and the associated fauna are indicators of a distal platform setting (upper circalittoral zone). The Sainte-Scolasse fauna is relatively close to that of the Oxfordian of Haute-Saône (eastern France) and thus forms an intermediate assemblage between the communities from the shallow carbonate platforms (e.g., Solnhofen Lithographic Limestone Lagerstätten) and those from the bathyal zone (e.g., La Voulte-sur-Rhône Lagerstätte).; La faune du Jurassique moyen (Callovien) de Sainte-Scolasse-sur-Sarthe (Normandie, France) est remarquable par ces crustacés exceptionnellement conservés dans des niveaux de calcaire gréseux. La faune de crustacés est composée de cinq espèces appartenant aux Glypheidae, Erymidae et Longodromitidae. Les glyphées constituent le groupe le plus diversifié et abondant. Une description anatomique détaillée permet de proposer la première reconstitution de Glyphea dressieri Meyer in Bronn, 1837, et de mettre en évidence un dimorphisme sexuel marqué. Des observations similaires sont faites chez Glyphea regleyana (Desmarest, 1822). Une analyse quantitative basée sur 149 spécimens montre que deux espèces sont dominantes: Glyphea regleyana (47,0 % des spécimens) et G. dressieri (46,3 %). Le paléoenvironnement est interprété comme une vasière côtière largement ouverte sur la mer franche. Plus précisément, le faciès sédimentaire et la faune associée indiquent un milieu de plateforme distale (zone circalittorale supérieure). La faune de Sainte-Scolasse est relativement proche de celle de l'Oxfordien de Haute-Saône (Est de la France) et forme donc aussi un assemblage intermédiaire entre les communautés de plateformes carbonatées peu profondes (ex: Lagerstätten du Calcaire Lithographique de Solnhofen) et celles de la zone bathyale (ex: Lagerstätte de La Voulte-sur-Rhône).
Published: 2023

143. Gaussian derivative wavelet propagation in a single scattering bubbly water beyond resonant frequency

Author: Le Gonidec, Yves, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS]Physics [physics]
Abstract: Acoustic pulses transmitted across air bubbles in water are usually analyzed in the ν frequency domain to determine the attenuation coefficient and phase velocity for comparison with scattering and effective models. In the present work, acoustic experiments performed beyond the bubble resonant frequency in the single scattering regime highlight an amplitude decrease and a significant shape variability of the waveform with the propagation distance x, but also a nearly constant normalized amplitude spectrum. The amplitude spectrum can be characterized by a fractional derivative order γ x = κ γ x, with κ γ a constant defined by a numerical optimization method, and a time dilation factor δ x which effects compensate. The phase spectrum is shifted by π 2 γ x and explains the experimental waveform changes. The phase velocity can be approximated to ṽ0 /(1 − κ γ ṽ0 /4ν), where ṽ0 is similar to the sound speed in water. It is also shown that the waveform shape, quantified by γ x , is correlated to the waveform amplitude. The results highlight potential interests in underwater communication.
Published: 2023

144. Remagnetization Under Hydrothermal Alteration of South Tibetan Paleocene Lavas: Maghemitization, Hematization, and Grain Size Reduction of (Titano)magnetite

Author: Wentao Huang, Shanshan Niu, Mark J. Dekkers, Peter C. Lippert, Dario Bilardello, Peat Solheid, Bo Zhang, Guillaume Dupont‐Nivet, Douwe J. J. van Hinsbergen, Lin Ding, Paleomagnetism, Mantle dynamics & theoretical geophysics, State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Chinese Academy of Sciences [Beijing] (CAS), North China Electric Power University, Utrecht University [Utrecht], University of Utah, University of Minnesota, University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, Key Laboratory of Orogenic Belts and Crustal Evolution, Peking University [Beijing], Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Second Tibetan Plateau Scientific Expedition and 788Research Program (STEP, grant No. 2019QZKK0708), Natural Science Foundation of China (NSFC) project Basic Science Center for Tibetan Plateau Earth System (BCTES, grant No. 79041988101), and Institute for Rock Magnetism (IRM) at the University of Minnesota - NSF Instruments and Facilities program (grant n°2202)
Subjects: [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, Remagnetization, hematite, maghemite, Tibetan plateau, Geophysics, Geochemistry and Petrology, Space and Planetary Science, titanomagnetite, Earth and Planetary Sciences (miscellaneous), Tibetan Plateau, remagnetization
Abstract: International audience; The Paleocene lavas from Dianzhong Formation (E1d) in Linzhou basin of southern Lhasa terrane are a key target for paleomagnetic investigations into the timing and paleolatitude of the initial India-Asia collision. Controversy exists, however, on whether these rocks preserve a primary remanent magnetization. Here we reanalyze previously published thermal demagnetization data and report detailed rock magnetic results and petrographic observations of these rocks. We find that the original magnetic carrier, a magmatic multidomain Ti-poor titanomagnetite, underwent significant grain size reduction and was variably reacted to single-domain maghemite and nano-hematite. Such strong alteration may have resulted from successive hydrothermal events: a first event related to the ∼52 Ma dike intrusions into the E1d that accompanied a massive ignimbrite eruption deposited above the E1d producing heating up to 300 °C; and a secondary event related to the 42 - 27 Ma southward overthrusting of the basin, heating the E1d up to 130 – 145 °C. Unblocking/inversion temperature spectra of the authigenic maghemite and nano-hematite overlap with those of the titanomagnetite, implying that the primary remanence of the E1d lavas has been contaminated or replaced by thermoviscous and chemical remanent magnetizations. Thus the isolated characteristic remanent magnetization from these rocks, whether slightly or completely altered, cannot be considered primary and should not be used for paleolatitudinal determination. Our study confirms that hydrothermal alteration can seriously jeopardize the remanence carried by titanomagnetite and thus should be tested for paleomagnetic investigations of rock units from tectonically active areas.
Published: 2023

145. Le gisement de talc-chlorite de Trimouns

Author: de Saint Blanquat, Michel, De Parseval, Philippe, Boutin, Alexandre, Quesnel, Benoit, Poujol, Marc, Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES), Université Laval [Québec] (ULaval), Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)
Subjects: [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology, ComputingMilieux_MISCELLANEOUS, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract: Le gisement de talc-chlorites de Trimouns résulte de l’altération métasomatique de métasédiments paléozoïques, par des fluides aqueux et salés. Ce processus s’effectue entre 250 et 300 ºC à une profondeur inférieure à 5 km. Daté entre 120 et 90 millions d’années, il est lié à l’amincissement de la croûte continentale lors de l'hyper-extension provoquée par l’ouverture du Golfe de Gascogne.
Published: 2023

146. Impact of Inherited Foreland Relief on Retro‐Foreland Basin Architecture

Author: Benjamin Gérard, Delphine Rouby, Ritske S. Huismans, Cécile Robin, Charlotte Fillon, Jean Braun, Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire de Planétologie et Géosciences [UMR_C 6112] (LPG), Université d'Angers (UA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), University of Bergen (UiB), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Centre scientifique et Technique Jean Feger (CSTJF), TOTAL FINA ELF, GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), University of Potsdam = Universität Potsdam, and TotalEnergies
Subjects: Landscape evolution model, Source-to-Sink, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Sediment Routing System, Stratigraphy, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Earth and Planetary Sciences (miscellaneous), [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Orogenic belt, Foreland Basin, Flexure
Abstract: International audience; We use a Landscape Evolution Model including flexural isostasy to investigate the influenceof inherited foreland relief on the stratigraphic evolution of the retro-foreland domain during mountainbuilding. We show models with four different types of initial relief in the foreland domain: at sea level,elevated (+300 m), a 1 km-deep and 100 km-wide foreland basin associated with either a forebulge at sealevel or elevated at +300 m. During the first 10 Myr of simulation, the landscape evolution of the foreland issignificantly altered by its inherited bathymetry/topography. The impact is then smoothed out once the foreland slope has stabilized and develops a transverse drainage network. Models record a long-term shallowing-up mega-sequence driven by the increase in sediment production rate in the uplifting range and the decrease in the rate of flexural accommodation space creation in the foreland basin. The initial relief of the foreland domain alters the timing of its transition from the under-filled to the over-filled phase. An initially deep foreland basin is twice as thick as an initially elevated foreland. It records deep marine deposits while a foreland initially at sea level records thin shallow marine and an elevated foreland records continental deposits. The forebulge is buried by continental deposits in an initially elevated foreland while it is buried by marine sediments in other models. Alluvial fans at the foot of the range are more elevated in initially elevated forelands. We discuss our results of modeled stratigraphic architecture in comparison with the Pyrenean, Alpine and Andean retro-foreland basins.
Published: 2023

147. A new species of Pleuropholis (Teleostei: Pleuropholidae) from the Upper Cretaceous Akrabou Formation of southeastern Morocco, with comments on the evolutionary history of the genus

Author: Paulo M. Brito, Romain Vullo, Universidade do Estado do Rio de Janeiro [Rio de Janeiro] (UERJ), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) 305118/2021-8, and Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio De Janeiro (FAPERJ)E-26/201.172/2022
Subjects: Actinopterygii, New taxon, Africa, Neopterygii, Pleuropholid fish, Cretaceous Research, Paleontology, Cenomanian, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology
Abstract: International audience; A pleuropholid fish is described for the first time from the Upper Cretaceous (Cenomanian) Akrabou Formation, Agoult locality, southeastern Morocco. The new material, consisting of a single complete specimen, is attributed to a new species, Pleuropholis danielae, and is diagnosed by its slender body shape, the absence of a leptolepid notch in the dentary, a broad maxilla, covering almost the entirely lower jaw, and flank scales with an unserrated posterior margin. This species represents the last known occurrence of Pleuropholidae, a group so far unknown from the Late Cretaceous.
Published: 2023

148. Grimmipollis burmanica gen. et sp. nov.: New genus of the soapberry family (Sapindaceae) from the late Eocene of central Myanmar

Author: Huasheng Huang, Robert J. Morley, Raymond van der Ham, Limi Mao, Alexis Licht, Guillaume Dupont-Nivet, Zaw Win, Day Wa Aung, Carina Hoorn, University of Amsterdam [Amsterdam] (UvA), Università degli Studi di Firenze = University of Florence (UniFI), University of London [London], Naturalis Biodiversity Center [Leiden], Nanjing Institute of Geology and Palaeontology (NIGPAS-CAS), Chinese Academy of Sciences [Nanjing Branch], Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), University of Potsdam = Universität Potsdam, Shwe Bo University, University of Yangon, China Scholarship Council (CSC grant 201604910677), University of Amsterdam, ANR-19-ERC7-0007,DISPERSAL,Un contrôle tectonique ou climatique sur la dispersion des premiers primates ? Investigation de la dynamique des espèces invasives au cours des temps géologiques(2019), and European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015)
Subjects: Paleontology, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Ecology, Evolution, Behavior and Systematics
Abstract: International audience; As a crossroads for plant dispersal between Laurasia and Gondwana since at least the late Eocene, the Central Myanmar Basins have yielded rich and diverse fossil pollen. Here we report Grimmipollis burmanica, a new genus and species in the soapberry family (Sapindaceae) from the upper Eocene Yaw Formation in the Central Myanmar Basins. We also investigate its similarity of pollen sculpture with other selected genera using hierarchical cluster analysis, and its source paleoecology with pollen diagrams. Grimmipollis pollen grains are characterized by parasyncolporate apertures with an apocolpial field at each side, distinct margines along the colpi, arcuate, tuberculate and rope-shaped mesocolpial ridges, and prominent, verrucate or fossulate apocolpia. These features distinguish this genus from other syncolporate and parasyncolporate types in the extant Sapindaceae genera, and fossil pollen genera. As most syncolporate and parasyncolporate types occur in the tribe Cupanieae, G. burmanica is likely derived from an extinct Cupanieae and thus a rainforest tree species. The hierarchical cluster analysis confirms our establishment of Grimmipollis, and reveals it is morphologically close to Meyeripollis. The sedimentary environment from which these pollen grains were retrieved suggests that G. burmanica could be a member of seasonal swamp forests.
Published: 2023

149. Northward expansion of the southern-temperate podocarp forest during the Early Eocene Climatic Optimum: Palynological evidence from the NE Tibetan Plateau (China)

Author: Faez Robin-Champigneul, Julia Gravendyck, Huasheng Huang, Amber Woutersen, David Pocknall, Niels Meijer, G. Dupont-Nivet, Roy H.J. Erkens, C. Hoorn, Maastricht University [Maastricht], Leibniz Universität Hannover=Leibniz University Hannover, Rheinische Friedrich-Wilhelms-Universität Bonn, Università degli Studi di Firenze = University of Florence (UniFI), University of Amsterdam [Amsterdam] (UvA), Senckenberg Biodiversity and Climate Research Centre (SBiK-F), Goethe-Universität Frankfurt am Main-Senckenberg – Leibniz Institution for Biodiversity and Earth System Research - Senckenberg Gesellschaft für Naturforschung, Leibniz Association-Leibniz Association, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Naturalis Biodiversity Center [Leiden], and DFG, project nr. 471591895
Subjects: Podocarpaceae, Palaeobiogeography, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Morphometry, Phyllocladus, Paleontology, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Hyperthermal, Palaeoclimate, Ecology, Evolution, Behavior and Systematics
Abstract: International audience; The debated vegetation response to climate change can be investigated through palynological fossil records from past extreme climate conditions. In this context, the early Eocene (53.3 to 41.2 million years ago (Ma)) is often referred to as a model for a greenhouse Earth. In the Xining Basin, situated on the North-eastern Tibetan Plateau (NETP), this time interval is represented by an extensive and well-dated sedimentary sequence of evaporites and red mudstones. Here we focus on the palynological record of the Early Eocene Climatic Optimum (EECO; 53.3 to 49.1 Ma) and study the fossil gymnosperm pollen composition in these sediments. In addition, we also investigate the nearest living relatives (NLR) or botanical affinity of these genera and the paleobiogeographic implications of their occurrence in the Eocene of the NETP. To reach our objective, we complemented transmitted light microscopy with laser scanning- and electron microscopy techniques, to produce high-resolution images, and illustrate the morphological variation within fossil and extant gymnosperm pollen. Furthermore, a morphometric analysis was carried out to investigate the infra- and intrageneric variation of these and related taxa. To place the data in context we produced paleobiogeographic maps for Phyllocladidites and for other Podocarpaceae, based on data from a global fossil pollen data base, and compare these with modern records from GBIF. We also assessed the climatic envelope of the NLR. Our analyses confirm the presence of Phyllocladidites (NLR Phyllocladus, Podocarpaceae) and Podocarpidites (NLR Podocarpus, Podocarpaceae) in the EECO deposits in the Xining Basin. In addition, a comparative study based on literature suggests that Parcisporites is likely a younger synonym of Phyllocladidites. Our findings further suggest that the Phyllocladidites specimens are derived from a lineage that was much more diverse than previously thought, and which had a much larger biogeographical distribution during the EECO than at present. Based on the climatic envelope of the NLR, we suggest that the paleoclimatic conditions in the Xining Basin were warmer and more humid during the EECO. We conclude that phylloclade-type conifers typical of the southern-temperate podocarp forests, had a northward geographical expansion during the EECO, followed by extirpation.
Published: 2023

150. Linking uplift, erosion, and sedimentation using landscape evolution models: Madagascar since the Late Cretaceous

Author: Ruohong Jiao, Jean Braun, Antoine Delaunay, Cécile Robin, François Guillocheau, GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), University of Victoria [Canada] (UVIC), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and Projekt DEAL
Subjects: Landscape evolution model, Chemical weathering, Erosion, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Geography, Planning and Development, Earth and Planetary Sciences (miscellaneous), Madagascar, Source to sink, Earth-Surface Processes, Sedimentary basin
Abstract: International audience; We present a study to estimate the large-scale landscape history of a continental margin, by establishing a source-to-sink volume balance between the eroding onshore areas and the offshore basins. Assuming erosion as the primary process for sediment production, we strive to constrain a numerical model of landscape evolution that balances the volumes of eroded materials from the continent and that deposited in the corresponding basins, with a ratio imposed for loss of erosion products. We use this approach to investigate the landscape history of Madagascar since the Late Cretaceous. The uplift history prescribed in the model is inferred from elevations of planation surfaces formed at various ages. By fitting the volumes of terrigenous sediments in the Morondava Basin along the west coast and the current elevation of the island, the landscape evolution model is optimized by constraining the erosion law parameters and ratios of sediment loss. The results include a best-fit landscape evolution model, which features two major periods of uplift and erosion during the Late Cretaceous and the middle to late Cenozoic. The model supports suggestions from previous studies that most of the high topography of the island was constructed since the middle to late Miocene, and on the central plateau the erosion has not reached an equilibrium with the high uplift rates in the late Cenozoic. Our models also indicate that over the geological time scale, a significant portion of materials eroded from Madagascar was not archived in the offshore basin, possibly consumed by chemical weathering, the intensity of which might have varied with climate.
Published: 2023

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