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53 results on '"Department of Earth Science [Bergen] (UiB)"'

1. Dansgaard-Oeschger and Heinrich event temperature anomalies in the North Atlantic set by sea ice, frontal position and thermocline structure

Author: J.B. Pedro, C. Andersson, G. Vettoretti, A.H.L. Voelker, C. Waelbroeck, T.M. Dokken, M.F. Jensen, S.O. Rasmussen, E.G. Sessford, M. Jochum, K.H. Nisancioglu, Australian Antarctic Division (AAD), Australian Government, Department of the Environment and Energy, Institute for Marine and Antarctic Studies [Hobart] (IMAS), University of Tasmania [Hobart, Australia] (UTAS), IT University of Copenhagen (ITU), NORCE Norwegian Research Center, Instituto Português de Investigação do Mar e da Atmosfera (IPMA), Centro de Ciências do Mar [Faro] (CCMAR), Universidade do Algarve (UAlg), Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Center for Earth Evolution and Dynamics, University of Oslo, University of Oslo (UiO), European Project: 610055,EC:FP7:ERC,ERC-2013-SyG,ICE2ICE(2014), and European Project: 339108,EC:FP7:ERC,ERC-2013-ADG,ACCLIMATE(2014)
Subjects: Archeology, Global and Planetary Change, Dansgaard-Oeschger event, [SDU]Sciences of the Universe [physics], marine sediment core, Heinrich event, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, ice core, Ecology, Evolution, Behavior and Systematics, sea ice, abrupt climate change
Abstract: We use eighteen timescale-synchronised near-surface temperature reconstructions spanning 10-50 thousand years before present to clarify the regional expression of Dansgaard-Oeschger (D-O) and Heinrich (H) events in the North Atlantic. The North Atlantic Drift region shows D-O temperature variations of ca. 2-5?? with Greenland-like structure. The Western Iberian Margin region also shows Greenland-like structure, but with more pronounced surface cooling between interstadials and Heinrich stadials (ca. 6-9 ??C) than between interstadials and non-Heinrich stadials (ca. 2-3 ??C). The southern Nordic Seas show smaller D-O temperature anomalies (ca. 1-2 ??C) that appear out of phase with Greenland. These spatial patterns are replicated in a new global climate model simulation that features unforced (D-O-like) and freshwater forced (H-like) abrupt climate changes. The model simulations and observations suggest consistently that the spatial expression and amplitude of D-O and H event temperature anomalies are dominated by coupled changes in the Atlantic Meridional Overturning, sea ice extent, polar front position and thermocline structure. ?? 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). info:eu-repo/semantics/publishedVersion
Published: 2022
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2. Rotation, narrowing, and preferential reactivation of brittle structures during oblique rifting

Author: Guillaume Duclaux, Dave A. May, Ritske S. Huismans, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Institute of Geophysics [ETH Zürich], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA), Department of Earth Science [Bergen], University of Bergen (UIB), Department of Earth Sciences, Institute of Geophysics, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), and Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])
Subjects: bepress|Physical Sciences and Mathematics, 010504 meteorology & atmospheric sciences, bepress|Physical Sciences and Mathematics|Earth Sciences|Tectonics and Structure, bepress|Physical Sciences and Mathematics|Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Slip (materials science), EarthArXiv|Physical Sciences and Mathematics|Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, 03 medical and health sciences, 0302 clinical medicine, Geochemistry and Petrology, Lithosphere, Passive margin, Earth and Planetary Sciences (miscellaneous), 0105 earth and related environmental sciences, 030304 developmental biology, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, 0303 health sciences, Rift, Transtension, Oblique case, EarthArXiv|Physical Sciences and Mathematics, Tectonics, Geophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], EarthArXiv|Physical Sciences and Mathematics|Earth Sciences|Tectonics and Structure, Shear zone, Seismology, Geology, 030217 neurology & neurosurgery
Abstract: Occurrence of multiple faults populations with contrasting orientations in oblique continental rifts and passive margins has long sparked debate about relative timing of deformation events and tectonic interpretations. Here, we use high-resolution three-dimensional thermo-mechanical numerical modeling to characterize the evolution of the structural style associated with varying geometries of oblique rifting in a layered continental lithosphere. Automatic analysis of the distribution of active extensional shear zones at the surface of the model demonstrates a characteristic sequence of deformation. Phase 1 with initial localization of deformation and development of wide moderately oblique en-echelon grabens limited by extensional shear zones oriented close to orthogonal to σ 3 trend. Subsequent widening of the grabens is accompanied by progressive rotation of the phase 1 extensional shear zones to an orientation sub-orthogonal to the plate motion direction. Phase 2 is characterized by narrowing of active deformation resulting from thinning of the continental mantle lithosphere and development of a second-generation of extensional shear zones. During phase 2 deformation localizes both on plate motion direction-orthogonal structures that reactivate rotated phase 1 shear zones, and on new moderately oblique structures parallel to σ 2 . Finally, phase 3 consists in the oblique rupture of the continental lithosphere and produces an oceanic domain where oblique ridge segments are linked with highly oblique accommodation zones. We conclude that while new structures form and trend parallel to σ 2 in an oblique rift, progressive rotation and long-term slip along phase 1 structures promotes orthorhombic fault systems, which accommodate upper crustal extension and control oblique passive margin architecture. The distribution, orientation, and evolution of frictional-plastic structures observed in our models consistent with documented fault populations in the Main Ethiopian Rift and the Gulf of Aden conjugate passive margins, both of which developed in moderately oblique extensional settings.
Published: 2020
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3. Dynamics of Spontaneous (Multi) Centennial‐Scale Variations of the Atlantic Meridional Overturning Circulation Strength During the Last Interglacial

Author: Didier M. Roche, Nathaelle Bouttes, Augustin Kessler, Ulysses S Ninnemann, Jerry Tjiputra, Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), Modélisation du climat (CLIM), 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), Vrije Universiteit Amsterdam [Amsterdam] (VU), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), 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)-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), and Earth Sciences
Subjects: Convection, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Lead (sea ice), Paleontology, Wind stress, Inflow, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Latitude, Bottom water, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Interglacial, Sea ice, SDG 14 - Life Below Water, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Recent reconstructions of bottom water δ 13 C during the last interglacial (LIG) suggest short-lived variability in the Atlantic meridional overturning circulation (AMOC). Spontaneous (multi) centennial-scale variability of the AMOC simulated in the Earth system model of intermediate complexity iLOVECLIM are investigated for that period. The model simulates abrupt AMOC transitions occurring at 300 years frequency and correspond to a switch of the AMOC vigor between a strong (∼17 Sv) and a weak (∼11 Sv) state. The onset of these abrupt transitions is associated with changes in orbital forcings resulting in the decline of summer insolation in the high latitudes of the North Atlantic and affecting the sea ice cover in two key deep convection regions: (1) the northern Nordic Seas (NNS) and (2) the northwest North Atlantic (NWNA). Northward inflow of Atlantic surface water increases the convection depth in (1) and strengthens the Greenland Iceland Norway (GIN) Seas overturning circulation. Subsequent ocean-atmosphere interactions involving sea ice, ocean heat release, anomalies of evaporation-precipitation, and wind stress over the Nordic Seas lead also to an increase in deep convection in (2), followed by increase in the AMOC strength.
Published: 2020
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4. Shallow-water hydrothermalism at Milos (Greece): Nature, distribution, heat fluxes and impact on ecosystems

Author: Anders Schouw, Javier Escartín, Valentine Puzenat, Sven Le Moine Bauer, Othonas Vlasopoulos, Nuno Gracias, Rafael Garcia, Paraskevi N. Polymenakou, Lluís Magí, Manolis Mandalakis, Guillem Vallicrosa, William D. Orsi, Steffen Leth Jørgensen, Varvara Antoniou, Thibaut Barreyre, Jean-Emmanuel Martelat, Ömer K. Coskun, Pascal Allemand, Paraskevi Nomikou, Philippe Grandjean, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Sciences de la Terre (LST), 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)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), National and Kapodistrian University of Athens (NKUA), Universitat de Girona (UdG), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), 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), Ludwig-Maximilians-Universität München (LMU), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Universitat de Girona [Girona], 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), and Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon)
Subjects: Shore, Convection, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Geochemistry, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Geology, Context (language use), 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Seafloor spreading, Hydrothermal circulation, Waves and shallow water, 13. Climate action, Geochemistry and Petrology, Outflow, 14. Life underwater, Bioturbation, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Submarine hydrothermal activity is responsible for heat and chemical exchanges through the seafloor. Shallow-water hydrothermal systems (SWHS), while identified around the globe, are often studied in a way that is less comprehensive than their deep-ocean counterparts (e.g., along ridges), where systematic optical and acoustic mapping is more prevalent and coupled to in situ observations and sampling. Using aerial drones, an AUV, and temperature measurements at 10–40 cm subseafloor, we investigated in 2019 one of the most extensive SWHS known to date, in Paleochori and nearby Spathi and Agia Kyriaki Bays (south of Milos, Greece). Hydrothermal venting, found from the shore to water depths of almost 500 m, shows emissions of gases and high-temperature fluids, often associated with bacterial mats and/or hydrothermal mineral precipitates. This study provides extensive drone mapping coupled with local AUV surveys for seafloor characterization and ground-truthing from the shore to ~20 m water depth. Seafloor photomosaics also provide a detailed context to samples, measurements and observations carried in situ. We interpret the photomosaics to define distinct seafloor types, linked to this hydrothermal activity. White hydrothermal patches (WHPs) often show a clear polygonal organization, together with outflow areas that are both more dispersed and distributed. Polygonal patterns likely result from fluid convection in a sandy porous medium heated from below. These WHPs display elevated subseafloor temperatures, typically >50°C, with maximum values of ~75°C. Photomosaics also display textures of biological origin, including seagrass and bioturbation patterns. Widespread bioturbation by burrowing shrimps is often associated with WHPs, bounding them, but also occurs on sandy seafloor away from hydrothermal patterns. Subseafloor temperatures at these bioturbated areas are of ~30–40°C, and are thus transitional between hot WHPs and sedimented seafloor unaffected by hydrothermal activity (~24°C). In addition to linking subseafloor temperature data and interpreted seafloor photomosaics, our results provide a comprehensive general overview of this SWHS, of the organization of its hydrothermal outflow through the seafloor, and of the underlying subseafloor fluid circulation. This paper also gives the first perspectives on the heat fluxes of the system, and constitutes a background for other studies on the nature and distribution of microbial communities, controlled by this hydrothermal activity.
Published: 2021
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5. Interaction of an antecedent fluvial system with early normal fault growth: Implications for syn-rift stratigraphy, western Corinth rift (Greece)

Author: Romain Hemelsdaël, Mary Ford, Fabrice Malartre, Rob L. Gawthorpe, 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), GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Earth Science [Bergen] (UiB), and University of Bergen (UiB)
Subjects: Antecedent river, 010504 meteorology & atmospheric sciences, Stratigraphy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Fluvial, Active fault, Sinuosity, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, fault migration, rift basin, Geomorphology, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Rift, fluvial system, Geology, 15. Life on land, conglomerate, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Facies, Sedimentary rock, Progradation, Fault block
Abstract: International audience; Continental ‘overfilled’ conditions during rift initiation are conventionally explained as due to low creation of accommodation compared with sediment supply. Alternatively, sediment supply can be relatively high from the onset of rifting due to an antecedent drainage system. The alluvial Lower Group of the western Plio–Pleistocene Corinth rift is used to investigate the interac- tion of fluvial sedimentation with early rifting. This rift was obliquely super- imposed on the Hellenide mountain belt from which it inherited a significant palaeorelief. Detailed sedimentary logging and mapping of the well-exposed syn-rift succession document the facies distributions, palaeocurrents and stratigraphic architecture. Magnetostratigraphy and bios- tratigraphy are used to date and correlate the alluvial succession across and between fault blocks. From 3!2 to 1!8 Ma, a transverse low sinuosity braided river system flowed north/north-east to east across east–west-striking active fault blocks (4 to 7 km in width). Deposits evolved downstream from coarse alluvial conglomerates to fine-grained lacustrine deposits over 15 to 30 km. The length scale of facies belts is much greater than, and thus not directly controlled by, the width of the fault blocks. At its termination, the distribu- tive river system built small, stacked deltas into a shallow lake margin. The presence of a major antecedent drainage system is supported by: (i) a single major sediment entry point; (ii) persistence of a main channel belt axis; (iii) downstream fining at the scale of the rift basin. The zones of maximum sub- sidence on individual faults are aligned with the persistent fluvial axis, sug- gesting that sediment supply influenced normal fault growth. Instead of low accommodation rate during the early rift phase, this study proposes that facies progradation can be controlled by continuous and high sediment sup- ply from antecedent rivers.
Published: 2017
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6. Observing System Evaluation Based on Ocean Data Assimilation and Prediction Systems: On-Going Challenges and a Future Vision for Designing and Supporting Ocean Observational Networks

Author: Pierre Brasseur, Gregory C. Smith, Mounir Benkiran, Cyril Germineaud, George R. Halliwell, Matthew Martin, Yosuke Fujii, Patrick Heimbach, James Cummings, Elisabeth Remy, Pierre Yves Le Traon, Benoît Tranchant, Magdalena Balmaseda, Shastri Paturi, Antonio Bonaduce, Young Ho Kim, Norihisa Usui, Nora Loose, Hao Zuo, Gilles Larnicol, Florent Gasparin, Shuhei Masuda, Peter R. Oke, Villy Kourafalou, Craig Donlon, D. J. Lea, Laurent Bertino, Yan Xue, Jiping Xie, Meteorological Research Institute [Tsukuba] (MRI), Japan Meteorological Agency (JMA), Mercator Océan, Société Civile CNRS Ifremer IRD Météo-France SHOM, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), European Centre for Medium-Range Weather Forecasts (ECMWF), CISRO Oceans and Atmosphere, NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML), National Oceanic and Atmospheric Administration (NOAA), Oden Institute for Computational Engineering and Sciences, University of Texas at Austin [Austin], Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), NOAA National Centers for Environmental Prediction (NCEP), Nansen Environmental and Remote Sensing Center [Bergen] (NERSC), NCEP Climate Prediction Center (CPC), NOAA National Weather Service (NWS), Research Institute for Global Change (RIGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Environment and Climate Change Canada, Cooperative Institute for Marine and Atmospheric Studies (CIMAS), Rosenstiel School of Marine and Atmospheric Science (RSMAS), University of Miami [Coral Gables]-University of Miami [Coral Gables], Met Office Climate Research Division, United Kingdom Met Office [Exeter], Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Helmholtz-Zentrum Geesthacht (GKSS), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-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]), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Ocean Circulation and Climate Research Center, Korea Institute of Ocean Science and Technology (KIOST), Department of Ocean Sciences, University of Miami [Coral Gables], and European Space Agency (ESA)
Subjects: 0106 biological sciences, Ocean observations, 010504 meteorology & atmospheric sciences, lcsh:QH1-199.5, Computer science, Underwater glider, Ocean Engineering, Aquatic Science, lcsh:General. Including nature conservation, geographical distribution, Oceanography, 01 natural sciences, ocean prediction, Data assimilation, Robustness (computer science), 14. Life underwater, Altimeter, lcsh:Science, Reliability (statistics), 0105 earth and related environmental sciences, Water Science and Technology, Global and Planetary Change, GODAE OceanView, 010604 marine biology & hydrobiology, observing system evaluation, ocean data assimilation, OSE (observing system experiment), 13. Climate action, [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences, Systems engineering, Observational study, Satellite, lcsh:Q, OSSE (observing system simulation experiment)
Abstract: This paper demonstrates the value of Observing System Evaluation (OS-Eval) efforts which have been made or are ongoing to contribute to observing system review and design with the support of Ocean Data Assimilation and Prediction (ODAP) communities such as GODAE OceanView and CLIVAR-GSOP, by highlighting examples that illustrate the potential of the related OS-Eval methodologies and recent achievements. For instance, Observing System Experiment (OSE) studies illustrate the impacts of the severe decrease in the number of TAO buoys during 2012-2014 and TRITON buoys since 2013 on ODAP system performance. Multi-system evaluation of the impacts of assimilating satellite sea surface salinity data based on OSEs has been performed to demonstrate the need to continue and enhance satellite salinity missions. Impacts of underwater gliders have been assessed using Observing System Simulation Experiments (OSSEs) to provide guidance on effective coordination of the western North Atlantic observing system elements. OSSEs are also being performed under H2020 AtlantOS project with the goal to enhance and optimize the Atlantic in-situ networks. Potential of future satellite missions of wide-swash altimetry and surface ocean currents monitoring is explored through OSSEs and evaluation of Degrees of Freedom for Signal (DFS). Forecast Sensitivity Observation Impacts (FSOI) are routinely evaluated for monitoring the ocean observation impacts in the US Navy’s ODAP system. Perspective on the extension of OS-Eval to the deep ocean, polar regions, coupled data assimilation, and biogeochemical applications are also presented. Based on the examples above, we identify the limitations of OS-Eval, indicating that the most significant limitation is reduction of robustness and reliability of the results due to their system-dependency. Inability of performing evaluation in near real time is also critical. A strategy to mitigate the limitation and to strengthen the impact of evaluations is discussed. In particular, we emphasize the importance of collaboration within the ODAP community for multi-system evaluation and communication with ocean observational communities on the design of OS-Eval, required resources, and effective distribution of the results. Finally, we recommend to further develop OS-Eval activities at international level with the support of the international ODAP (e.g., OceanPredict and CLIVAR-GSOP) and observational communities.
Published: 2019
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7. Terrestrial shallow water hydrothermal outflow characterized from out of space

Author: Jean-Emmanuel Martelat, Javier Escartín, Thibaut Barreyre, 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), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), 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), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), and 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)
Subjects: 010504 meteorology & atmospheric sciences, Earth science, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Context (language use), 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Hydrothermal circulation, Hydrothermal activity, Geochemistry and Petrology, Satellite imagery, Seafloor mapping, 14. Life underwater, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, [SDE.IE]Environmental Sciences/Environmental Engineering, Shallow water, Geology, Spectral bands, Plume, Waves and shallow water, Volcano, Volcanic island, 13. Climate action, Outflow
Abstract: International audience; We investigate the potential of satellite imagery to map and monitor the activity of shallow-water hydrothermal systems, which are often found around volcanic islands. For this study, we used publicly available data and proprietary WorldView-2 satellites images, with spectral bands that can penetrate up to water depths of 30 m. Shallow water hydrothermal sites are visible on satellite imagery, primarily with publicly available data, demonstrating the potential of satellite imagery to study and monitor shallow water hydrothermal activity. We focus our work on volcanic islands, showing intense near-shore, shallow-water hydrothermal activity, and distinct styles of hydrothermal venting. Satellite imagery constrains regional outflow geometry and the temporal variability or stability of these systems. Milos Island shows hydrothermal outflow associated with reflective mineral precipitates and/or bacterial mats, which are stable over time (2010–2014). These outflows locally define polygonal patterns likely associated with hydrothermal convection in porous media. In Kueishantao Island individual hydrothermal plumes charged with particles are visible at the sea surface, and display great variability in intensity and distribution of plume sources (2002–2019). Worldwide we have identified ~15 shallow water hydrothermal sites with satellite imagery, that are similar to either the Milos system (e.g., Vulcano and Panarea, Italy), or the Kueishantao system (numerous sites in Pacific volcanic islands). This study demonstrates that satellite imagery can be used to map and monitor different types of shallow-water hydrothermal systems, at regional scale, and monitor their evolution. Satellite data provide not only regional and temporal information on these systems, unavailable to date, but also the regional context for follow-up in situ field data and observations (e.g., instrumental monitoring, sampling, observations and mapping with divers or AUVs) to understand both the nature and dynamics of these systems, and ultimately the associated fluxes.
Published: 2020
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8. Drainage integration and sediment dispersal in active continental rifts: A numerical modelling study of the central Italian Apennines

Author: Rob L. Gawthorpe, Patience A. Cowie, Anneleen H. Geurts, Luke N J Wedmore, Vivi Kathrine Pedersen, Ritske S. Huismans, Guillaume Duclaux, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institute of Geophysics and Tectonics, School of Earth and Environment, University of Leeds, Department of Earth Science [Bergen], University of Bergen (UIB), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA), and Géoazur, Publications
Subjects: 010504 meteorology & atmospheric sciences, Basin stratigraphy, Fluvial, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Transient landscape evolution, Continental rifts, Structural basin, Overspill, 010502 geochemistry & geophysics, 01 natural sciences, Headward erosion, Paleontology, Drainage, 0105 earth and related environmental sciences, Central Apennines Italy, Rift, Sediment, Geology, 15. Life on land, Drainage integration, Extension and normal faulting, 13. Climate action, Erosion, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, Surface process modelling, Tectonic geomorphology
Abstract: International audience; Progressive integration of drainage networks during active crustal extension is observed in continental areas around the globe. This phenomenon is often explained in terms of headward erosion, controlled by the distance to an external base‐level (e.g. the coast). However, conclusive field evidence for the mechanism(s) driving integration is commonly absent as drainage integration events are generally followed by strong erosion. Based on a numerical modelling study of the actively extending central Italian Apennines, we show that overspill mechanisms (basin overfilling and lake overspill) are more likely mechanisms for driving drainage integration in extensional settings and that the balance between sediment supply vs. accommodation creation in fault‐bounded basins is of key importance. In this area drainage integration is evidenced by lake disappearance since the early Pleistocene and the transition from internal (endorheic) to external drainage, i.e. connected to the coast. Using field observations from the central Apennines, we constrain normal faulting and regional surface uplift within the surface process model CASCADE (Braun & Sambridge, 1997, Basin Research, 9, 27) and demonstrate the phenomenon of drainage integration, showing how it leads to the gradual disappearance of lakes and the transition to an interconnected fluvial transport system over time. Our model results show that, in the central Apennines, the relief generated through both regional uplift and fault‐block uplift produces sufficient sediment to fill the extensional basins, enabling overspill and individual basins to eventually become fluvially connected. We discuss field observations that support our findings and throw new light upon previously published interpretations of landscape evolution in this area. We also evaluate the implications of drainage integration for topographic development, regional sediment dispersal and offshore sediment supply. Finally, we discuss the applicability of our results to other continental rifts (including those where regional uplift is absent) and the importance of drainage integration for transient landscape evolution.
Published: 2018
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9. Insights Into the Crustal-Scale Dynamics of a Doubly Vergent Orogen From a Quantitative Analysis of Its Forelands: A Case Study of the Eastern Pyrenees

Author: Arjan R. Grool, Frédéric Christophoul, Armin Dielforder, Mary Ford, Jaume Vergés, Ritske S. Huismans, Agence Nationale de la Recherche (France), 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), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Institute of Earth Sciences Jaume Almera, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), 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), CSIC. Grant Number: PIE-CSIC-201530E082, French-Norwegian Foundation. Grant Number: 13-06 PYR-FFTP, and ANR-11-BS56-0031,PYRAMID,Le Nord des Pyrénées: évaluation intégrée de l'histoire de la Migration des fluides, l'Inversion du rift, le rôle des processus de surface et la Déformation dans un (rétro)prisme orogénique.(2011)
Subjects: Foreland fold-and-thrust belt, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Crustal-scale dynamics, Doubly vergent, Pyrenees, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Sedimentary basin, 010502 geochemistry & geophysics, Cross-section restoration, 01 natural sciences, Paleontology, Geophysics, [SDU]Sciences of the Universe [physics], Geochemistry and Petrology, Fold and thrust belt, Foreland basin, Geology, 0105 earth and related environmental sciences, Quantitative
Abstract: In natural doubly vergent orogens, the relationship between the pro- and retro-wedges is, as yet, poorly constrained. We present a detailed tectonostratigraphic study of the retro-wedge of the Eastern Pyrenees (Europe) and link its evolution to that of the pro-wedge (Iberia) in order to derive insight into the crustal-scale dynamics of doubly vergent orogens. Based on cross-section restoration and subsidence analyses, we divide the East Pyrenean evolution into four phases. The first phase (Late Cretaceous) is characterized by closure of an exhumed mantle domain between the Iberian and European plates and inversion of a salt-rich, thermally unequilibrated rift system. Overall shortening (~1 mm/yr) was distributed roughly equally between both margins over some 20 Myr. A quiescent phase (Paleocene) was apparently restricted to the retro-wedge with slow, continuous deformation in the pro-wedge (~0.4 mm/yr). This phase occurred between closure of the exhumed mantle domain and onset of main collision. The main collision phase (Eocene) records the highest shortening rate (~3.1 mm/yr), which was predominantly accommodated in the pro-wedge. During the final phase (Oligocene), the retro-wedge was apparently inactive, and shortening of the pro-wedge slowed (~2.2 mm/yr). Minimum total shortening of the Eastern Pyrenees is ~111 km, excluding closure of the exhumed mantle domain. The retro-wedge accommodated ~20 km of shortening. The shortening distribution between the pro- and retro-wedges evolved from roughly equal during rift inversion to pro-dominant during main collision. This change in shortening distribution may be intrinsic to all inverted rift systems. ©2018. American Geophysical Union., This study was funded by the ANR (France) PYRAMID research project. The French-Norwegian Foundation (13-06 PYR-FFTP; sedimentary basin and North Pyrenean foreland fold and thrust belt formation) supported study visits to the University of Bergen, Norway. Collaboration with CSIC Barcelona, Spain was funded by the project ALPIMED (PIE-CSIC-201530E082).
Published: 2018
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10. Climate variability in the subarctic area for the last 2 millennia

Author: M. Nicolle, M. Debret, N. Massei, C. Colin, A. deVernal, D. Divine, J. P. Werner, A. Hormes, A. Korhola, H. W. Linderholm, Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Norwegian Polar Institute, The Arctic University of Norway (UiT), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), University of Gothenburg (GU), University of Helsinki, Environmental Sciences, Environmental Change Research Unit (ECRU), and Helsinki Institute of Sustainability Science (HELSUS)
Subjects: 1171 Geosciences, PACIFIC DECADAL OSCILLATION, TEMPERATURE VARIABILITY, 010506 paleontology, 010504 meteorology & atmospheric sciences, lcsh:Environmental protection, Stratigraphy, [SDE.MCG]Environmental Sciences/Global Changes, Climate change, 01 natural sciences, lcsh:Environmental pollution, PAST MILLENNIUM, Paleoclimatology, Atlantic multidecadal oscillation, Sea ice, Ice age, HOLOCENE, lcsh:TD169-171.8, RECONSTRUCTION, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, lcsh:Environmental sciences, Holocene, 0105 earth and related environmental sciences, VDP::Mathematics and natural science: 400, lcsh:GE1-350, Global and Planetary Change, geography, geography.geographical_feature_category, ATLANTIC MULTIDECADAL OSCILLATION, Paleontology, VDP::Matematikk og Naturvitenskap: 400, Subarctic climate, TREE-RING CHRONOLOGIES, NORTHERN-HEMISPHERE, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, lcsh:TD172-193.5, ICE-AGE, SEA-ICE, Pacific decadal oscillation
Abstract: To put recent climate change in perspective, it is necessary to extend the instrumental climate records with proxy data from paleoclimate archives. Arctic climate variability for the last 2 millennia has been investigated using statistical and signal analyses from three regionally averaged records from the North Atlantic, Siberia and Alaska based on many types of proxy data archived in the Arctic 2k database v1.1.1. In the North Atlantic and Alaska, the major climatic trend is characterized by long-term cooling interrupted by recent warming that started at the beginning of the 19th century. This cooling is visible in the Siberian region at two sites, warming at the others. The cooling of the Little Ice Age (LIA) was identified from the individual series, but it is characterized by wide-range spatial and temporal expression of climate variability, in contrary to the Medieval Climate Anomaly. The LIA started at the earliest by around AD 1200 and ended at the latest in the middle of the 20th century. The widespread temporal coverage of the LIA did not show regional consistency or particular spatial distribution and did not show a relationship with archive or proxy type either. A focus on the last 2 centuries shows a recent warming characterized by a well-marked warming trend parallel with increasing greenhouse gas emissions. It also shows a multidecadal variability likely due to natural processes acting on the internal climate system on a regional scale. A ∼ 16–30-year cycle is found in Alaska and seems to be linked to the Pacific Decadal Oscillation, whereas ∼ 20–30- and ∼ 50–90-year periodicities characterize the North Atlantic climate variability, likely in relation with the Atlantic Multidecadal Oscillation. These regional features are probably linked to the sea ice cover fluctuations through ice–temperature positive feedback.
Published: 2018
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11. Author Correction: High-resolution record reveals climate-driven environmental and sedimentary changes in an active rift

Author: Natalia Zakharova, Liliane Janikian, Emilio Herrero-Bervera, Casey W. Nixon, Lisa C. McNeill, Jack Gillespie, Shunli Li, Spyros Sergiou, Gino de Gelder, Erwan Le Ber, Richard E. Ll. Collier, Joana Seguin, Mary Ford, Paula Diz, Romain Hemelsdaël, Rob L. Gawthorpe, Abah P. Omale, Georgios Michas, M. Ismaiel, Clint Miller, Marcie Purkey Phillips, Kostas Panagiotopoulos, Maria Geraga, Sofia Pechlivanidou, Gareth D. O. Carter, Mai-Linh Doan, Malka L. Machlus, Simone Sauer, S. Green, Marco Maffione, Jeremy D. Everest, Sabire Asli Oflaz, Aleksandra Cvetkoska, Donna J. Shillington, Katerina Kouli, Carol Mahoney, Ocean and Earth Science [Southampton], University of Southampton-National Oceanography Centre (NOC), Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], British Geological Survey [Edinburgh], British Geological Survey (BGS), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Rice University [Houston], University of Texas at Austin [Austin], School of Earth and Environment [Leeds] (SEE), University of Leeds, Department of Animal Ecology and Systematics, Justus-Liebig-Universität Gießen = Justus Liebig University (JLU), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Universidade de Vigo, 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]), 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), University of Patras, Department of Earth Sciences [Adelaide], University of Adelaide, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Hawaii Institute of Geophysics and Planetology (HIGP), University of Hawai‘i [Mānoa] (UHM), University of Hyderabad, Universidade Federal de São Paulo, National and Kapodistrian University of Athens (NKUA), Department of Geology [Leicester], University of Leicester, China University of Geosciences [Beijing], School of Geography, Earth and Environmental Sciences [Birmingham], University of Birmingham [Birmingham], Kingsborough Community College [CUNY] (KBCC), City University of New York [New York] (CUNY), Technological Educational Institute of Crete, Christian-Albrechts-Universität zu Kiel (CAU), Louisiana State University (LSU), University of Cologne, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Department of Earth and Atmospheric Sciences [Michigan], Central Michigan University (CMU), and UK Research & Innovation (UKRI)Natural Environment Research Council (NERC)
Subjects: 0301 basic medicine, Multidisciplinary, Rift, lcsh:R, North Anatolian Fault, High resolution, lcsh:Medicine, 03 medical and health sciences, Paleontology, 030104 developmental biology, 0302 clinical medicine, [SDU]Sciences of the Universe [physics], ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Sedimentary rock, lcsh:Q, lcsh:Science, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), ComputingMilieux_MISCELLANEOUS, 030217 neurology & neurosurgery, Geology
Abstract: © 2019, The Author(s). This Article contains errors in Reference 40 which is incorrectly given as: Palyvos, N., Pantosti, D. & Zabci, C. Paleoseismological evidence of recent earthquakes on the 1967 Mudurnu Valley earthquake segment of the North Anatolian fault. Bull. Seis. Soc. Am. 97, 1646–1661 (2007).
Published: 2019
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12. Contractional deformation of porous sandstone: Insights from the Aztec Sandstone, SE Nevada, USA

Author: Haakon Fossen, Gregory Ballas, Atle Rotevatn, Luisa F. Zuluaga, Roger Soliva, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), 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), Bassins, and 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)
Subjects: Porous sandstone deformation, Contractional deformation, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Deformation bands, Geology, Orogeny, Cataclastic rock, Slip (materials science), 010502 geochemistry & geophysics, 01 natural sciences, Nappe, Shear (geology), Sedimentary rock, Petrology, Paleogene, Geomorphology, Sevier thrusting, 0105 earth and related environmental sciences
Abstract: International audience; Contractional deformation of highly porous sandstones is poorly explored, as compared to extensional deformation of such sedimentary rocks. In this work we explore the highly porous Aztec Sandstone in the footwall to the Muddy Mountain thrust in SE Nevada, which contains several types of deformation bands in the Buffington tectonic window: 1) Distributed centimeter-thick shear-enhanced compaction bands (SECBs) and 2) rare pure compaction bands (PCBs) in the most porous parts of the sandstone, cut by 3) thin cataclastic shear-dominated bands (CSBs) with local slip surfaces. Geometric and kinematic analysis of the SECBs, the PCBs and most of the CSBs shows that they formed during ∼E–W (∼100) shortening, consistent with thrusting related to the Cretaceous to early Paleogene Sevier orogeny of the North American Cordilleran thrust system. Based on stress path modeling, we suggest that the compactional bands (PCBs and SECBs) formed during contraction at relatively shallow burial depths, before or at early stages of emplacement of the Muddy Mountains thrust sheet. The younger cataclastic shear bands (CSBs, category 3), also related to E–W Sevier thrusting, are thinner and show larger shear offsets and thus more intense cataclasis, consistent with the initiation of cataclastic shear bands in somewhat less porous materials. Observations made in this work support earlier suggestions that contraction lead to more distributed band populations than what is commonly found in the extensional regime, and that shear-enhanced compaction bands are widespread only where porosity (and permeability) is high.
Published: 2015
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13. Holocene glacier fluctuations

Author: Gregory C. Wiles, Olga Solomina, Dominic A. Hodgson, Susan Ivy-Ochs, Lewis A. Owen, Raymond S. Bradley, Nicolás E. Young, Vincent Jomelli, Heinz Wanner, Atle Nesje, Andrew Mackintosh, Institute of Geography, Russian Academy of Sciences, Moscow, Russian Federation, London School of Economics and Political Science (LSE), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Institute of Particle Physics, Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Institute for Social Marketing, Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Institute of Geography [Bern], University of Bern, The College of Wooster, Томский государственный университет Геолого-географический факультет Кафедра гидрологии, and Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris 1 Panthéon-Sorbonne (UP1)
Subjects: Archeology, Volcanic forcings, северное полушарие, Solar activity, Climate change, Neoglacial, голоцен, Glacier variations, Glacier mass balance, Holocene thermal maximum, Paleoclimatology, Glacial period, ComputingMilieux_MISCELLANEOUS, Ecology, Evolution, Behavior and Systematics, Holocene, Global and Planetary Change, geography, geography.geographical_feature_category, Orbital forcings, Global warming, оледенение, Geology, Glacier, [SHS.GEO]Humanities and Social Sciences/Geography, Modern glacier retreat, Lichenometry, 13. Climate action, Moraine, Climatology
Abstract: A global overview of glacier advances and retreats (grouped by regions and by millennia) for the Holocene is compiled from previous studies. The reconstructions of glacier fluctuations are based on 1) mapping and dating moraines defined by 14 C, TCN, OSL, lichenometry and tree rings (discontinuous records/time series), and 2) sediments from proglacial lakes and speleothems (continuous records/ time series). Using 189 continuous and discontinuous time series, the long-term trends and centennial fluctuations of glaciers were compared to trends in the recession of Northern and mountain tree lines, and with orbital, solar and volcanic studies to examine the likely forcing factors that drove the changes recorded. A general trend of increasing glacier size from the earlyemid Holocene, to the late Holocene in the extra-tropical areas of the Northern Hemisphere (NH) is related to overall summer temperature, forced by orbitally-controlled insolation. The glaciers in New Zealand and in the tropical Andes also appear to follow the orbital trend, i.e., they were decreasing from the early Holocene to the present. In contrast, glacier fluctuations in some monsoonal areas of Asia and southern South America generally did not follow the orbital trends, but fluctuated at a higher frequency possibly triggered by distinct teleconnections patterns. During the Neoglacial, advances clustered at 4.4e4.2 ka, 3.8e3.4 ka, 3.3e2.8 ka, 2.6 ka, 2.3e2.1 ka, 1.5e1.4 ka, 1.2e1.0 ka, 0.7e0.5 ka, corresponding to general cooling periods in the North Atlantic. Some of these episodes coincide with multidecadal periods of low solar activity, but it is unclear what mechanism might link small changes in irradiance to widespread glacier fluctuations. Explosive volcanism may have played a role in some periods of glacier advances, such as around 1.7e1.6 ka (coinciding with the Taupo volcanic eruption at 232 ± 5 CE) but the record of explosive volcanism is poorly known through the Holocene. The compilation of ages suggests that there is no single mechanism driving glacier fluctuations on a global scale. Multidecadal variations of solar and volcanic activity supported by positive feedbacks in the climate system may have played a critical role in Holocene glaciation, but further research on such linkages is needed. The rate and the global character of glacier retreat in the 20th through early 21st centuries appears unusual in the context of Holocene glaciation, though the retreating glaciers in most parts of the Northern Hemisphere are still larger today than they were in the early and/or mid-Holocene. The current retreat
Published: 2015
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14. Probabilistic Tsunami Hazard Analysis: Multiple Sources and Global Applications

Author: Grezio, Anita, Babeyko, Andrey, Baptista, Maria Ana, Behrens, Jörn, Costa, Antonio, Davies, Gareth, Geist, Eric L., Glimsdal, Sylfest, González, Frank I., Griffin, Jonathan, Harbitz, Carl B., Leveque, Randall J., Lorito, Stefano, Løvholt, Finn, Omira, Rachid, Mueller, Christof, Paris, Raphael, Parsons, Tom, Polet, Jascha, Power, William, Selva, Jacopo, Sørensen, Mathilde B., Thio, Hong Kie, Faculty of Earth and Life Sciences [Amsterdam] (FALW), Vrije Universiteit Amsterdam [Amsterdam] (VU), Hewlett-Packard Laboratories [Bristol], Hewlett-Packard, University of Washington [Seattle], Laboratoire Magmas et Volcans (LMV), 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), 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), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), URS Corporation, 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), Grezio, A., Babeyko, A., Baptista, M. A., Behrens, J., Costa, A., Davies, G., Geist, E. L., Glimsdal, S., Gonzalez, F. I., Griffin, J., Harbitz, C. B., Leveque, R. J., Lorito, S., Lovholt, F., Omira, R., Mueller, C., Paris, R., Parsons, T., Polet, J., Power, W., Selva, J., Sorensen, M. B., and Thio, H. K.
Subjects: tsunami source, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, hazard mapping, probabilistic tsunami hazard assessment, tsunami modeling, uncertainty analysis
Abstract: International audience; Applying probabilistic methods to infrequent but devastating natural events is intrinsicallychallenging. For tsunami analyses, a suite of geophysical assessments should be in principle evaluatedbecause of the diﬀerent causes generating tsunamis (earthquakes, landslides, volcanic activity,meteorological events, and asteroid impacts) with varying mean recurrence rates. Probabilistic TsunamiHazard Analyses (PTHAs) are conducted in diﬀerent areas of the world at global, regional, and local scaleswith the aim of understanding tsunami hazard to inform tsunami risk reduction activities. PTHAs enhanceknowledge of the potential tsunamigenic threat by estimating the probability of exceeding speciﬁclevels of tsunami intensity metrics (e.g., run-up or maximum inundation heights) within a certain period oftime (exposure time) at given locations (target sites); these estimates can be summarized in hazard mapsor hazard curves. This discussion presents a broad overview of PTHA, including (i) sources and mechanismsof tsunami generation, emphasizing the variety and complexity of the tsunami sources and their generationmechanisms, (ii) developments in modeling the propagation and impact of tsunami waves, and (iii)statistical procedures for tsunami hazard estimates that include the associated epistemic and aleatoricuncertainties. Key elements in understanding the potential tsunami hazard are discussed, in light of therapid development of PTHA methods during the last decade and the globally distributed applications,including the importance of considering multiple sources, their relative intensities, probabilities ofoccurrence, and uncertainties in an integrated and consistent probabilistic framework.
Published: 2017
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15. Reply to: 'The mountains of North-East Greenland are not remnants of the Caledonian topography. A comment on Pedersen et al. (2012)'

Author: Søren B. Nielsen, Kerry Gallagher, Vivi Kathrine Pedersen, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Department of Earth Sciences [Aarhus], Aarhus University [Aarhus], Terre, Temps, Traçage, 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)-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)-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: Topography, Vitrinite reflectance, 010504 meteorology & atmospheric sciences, Paleozoic, Passive margins, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, North east, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Geophysics, Fission track analysis, Erosion, Passive margin, Tectonophysics, Northeast Greenland, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: International audience; In this reply, we comment on the issues raised by Japsen, Chalmers, and Green [Japsen et al. (2013). The mountains of North-East Greenland are not remnants of the Caledonian topography. A comment on Pedersen et al. (2012): Tectonophysics]. We find that new vitrinite reflectance measurements from one location in the region may suggest a more complicated post-Caledonian evolution than proposed by Pedersen et al. (2012) for the southernmost part of the studied area. Overall, however, we cannot reconcile our AFT data set with a complete obliteration of the topography in late Paleozoic times, followed by episodic post-Caledonian exhumation and re-burial, as suggested by Japsen et al. (2013).
Published: 2013
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16. Glacier fluctuations during the past 2000 years

Author: Bao Yang, Lewis A. Owen, Áslaug Geirsdóttir, Kurt Nicolussi, Heinz Wanner, Raymond S. Bradley, Gifford H. Miller, Mariano Masiokas, Gregory C. Wiles, Atle Nesje, Darrell S. Kaufman, Johannes Koch, Olga Solomina, Aaron E. Putnam, Nicholas P. McKay, Vincent Jomelli, Institute of Geography, Russian Academy of Sciences, Moscow, Russian Federation, London School of Economics and Political Science (LSE), Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Northern Arizona University [Flagstaff], Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), University of Auckland [Auckland], Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Institut für Geographie, Universität Innsbruck [Innsbruck], Institute of Geography [Bern], University of Bern, The College of Wooster, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris 1 Panthéon-Sorbonne (UP1), Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Belfort-Montbeliard (UTBM)
Subjects: 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, Temperature change, 01 natural sciences, Neoglacial, Glacier mass balance, Glacier variations, Surge, Ecology, Evolution, Behavior and Systematics, Holocene, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Global and Planetary Change, geography, geography.geographical_feature_category, Tidewater glacier cycle, Geology, Glacier, [SHS.GEO]Humanities and Social Sciences/Geography, Cirque glacier, Glacier morphology, Modern glacier retreat, Late Holocene, Arctic, 13. Climate action, Climatology, Little Ice Age, Solar and volcanic activity
Abstract: A global compilation of glacier advances and retreats for the past two millennia grouped by 17 regions (excluding Antarctica) highlights the nature of glacier fluctuations during the late Holocene. The dataset includes 275 time series of glacier fluctuations based on historical, tree ring, lake sediment, radiocarbon and terrestrial cosmogenic nuclide data. The most detailed and reliable series for individual glaciers and regional compilations are compared with summer temperature and, when available, winter precipitation reconstructions, the most important parameters for glacier mass balance. In many cases major glacier advances correlate with multi-decadal periods of decreased summer temperature. In a few cases, such as in Arctic Alaska and western Canada, some glacier advances occurred during relatively warm wet times. The timing and scale of glacier fluctuations over the past two millennia varies greatly from region to region. However, the number of glacier advances shows a clear pattern for the high, mid and low latitudes and, hence, points to common forcing factors acting at the global scale. Globally, during the first millennium CE glaciers were smaller than between the advances in 13th to early 20th centuries CE. The precise extent of glacier retreat in the first millennium is not well defined; however, the most conservative estimates indicate that during the 1st and 2nd centuries in some regions glaciers were smaller than at the end of 20th/early 21st centuries. Other periods of glacier retreat are identified regionally during the 5th and 8th centuries in the European Alps, in the 3rd–6th and 9th centuries in Norway, during the 10th–13th centuries in southern Alaska, and in the 18th century in Spitsbergen. However, no single period of common global glacier retreat of centennial duration, except for the past century, has yet been identified. In contrast, the view that the Little Ice Age was a period of global glacier expansion beginning in the 13th century (or earlier) and reaching a maximum in 17th–19th centuries is supported by our data. The pattern of glacier variations in the past two millennia corresponds with cooling in reconstructed temperature records at the continental and hemispheric scales. The number of glacier advances also broadly matches periods showing high volcanic activity and low solar irradiance over the past two millennia, although the resolution of most glacier chronologies is not enough for robust statistical correlations. Glacier retreat in the past 100–150 years corresponds to the anthropogenic global temperature increase. Many questions concerning the relative strength of forcing factors that drove glacier variations in the past 2 ka still remain.
Published: 2016
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17. Stratigraphic signature of lithospheric deformation style in post-rift passive margin basins

Author: Rouby, Delphine, Huismans, Ritske, Robin, Cécile, Braun, Jean, Granjeon, Didier, 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), Department of Earth Science [Bergen] (UiB), 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), 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]), IFP Energies nouvelles (IFPEN), European Geosciences Union, 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-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), 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), 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.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy
Abstract: International audience; We revise commonly accepted models explaining long-term stratigraphic trends along Atlantic-type passive marginsby including the impact of complex lithosphere deformation at depth and it’s coupling with surface processes.To achieve this, we simulated the evolution of a passive margin basin using a cascade of three modeling tools: athermo-mechanical model of the syn-rift stretching of the lithosphere, a flexural and thermal model of the post-riftstage that includes coupling with surface processes and, finally, a stratigraphic model of the associated sedimentarybasin architecture. We compare two necking styles that lead to different margin geometries: wide and narrow marginsthat form by heterogeneous stretching. Wide margins, forming thinner and wider sedimentary wedges, showsignificantly larger aggradation component and longer preservation duration, in more continental/proximal depositionalfacies. Narrow margins are characterized by enhanced erosion and by-pass during transgression. Througha parametric analysis we constrain the relative contribution of lithosphere deformation and surface processes onthe stratigraphic trends and show that both may contribute equally to the stratigraphic architecture. For example,enhanced erosion in narrow margins impacts the volume of sediments delivered to the basin, which, in turn, significantlyincreases the subsidence. Our simulations also underline the importance of the assumed sediment transportlength, which controls whether the main depocentres remain in the necking zone or reach the more distal parts ofthe margin.
Published: 2016

18. First direct observation of coseismic slip and seafloor rupture along a submarine normal fault and implications for fault slip history

Author: Escartín, Javier, Leclerc, Frédérique, Olive, Jean-Arthur, Mevel, Catherine, Cannat, Mathilde, Petersen, Sven, Augustin, Nico, Feuillet, Nathalie, Deplus, Christine, Bezos, Antoine, Bonnemains, Diane, Chavagnac, Valérie, Choi, Yujin, Godard, Marguerite, Haaga, Kristian A., Hamelin, Cédric, Ildefonse, Benoit, Jamieson, John W., John, Barbara E., Leleu, Thomas, MacLeod, Christopher J., Massot-Campos, Miquel, Nomikou, Paraskevi, Paquet, Marine, Rommevaux-Jestin, Céline, Rothenbeck, Marcel, Steinführer, Anja, Tominaga, Masako, Triebe, Lars, Campos, Ricard, Gracias, Nuno, Garcia, Rafael, Andreani, Muriel, Vilaseca, Géraud, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Earth Observatory of Singapore (EOS), Nanyang Technological University [Singapour], Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), University of Wyoming (UW), Cardiff University, Universitat des Illes Balears, National and Kapodistrian University of Athens (NKUA), Texas A&M University [College Station], Universitat de Girona (UdG), 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), article financé par l'institut, Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Earth Observatory of Singapore, GEOMAR - Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Laboratoire de Planétologie et Géodynamique UMR6112 (LPG), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Department of Earth Science [Bergen], University of Bergen (UIB), National and Kapodistrian University of Athens = University of Athens (NKUA | UoA), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), 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 Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and 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)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, surface rupture, fault slip, Robots submarins, submarine fault, Falles (Geologia), Geophysics, microbathymetry, Space and Planetary Science, Geochemistry and Petrology, Underwater robots, earthquake, Faults (Geology), Earth and Planetary Sciences (miscellaneous), neotectonics, QE, Geology::Volcanoes and earthquakes [Science]
Abstract: International audience; Properly assessing the extent and magnitude of fault ruptures associated with large earthquakes is critical for understanding fault behavior and associated hazard. Submarine faults can trigger tsunamis, whose characteristics are defined by the geometry of seafloor displacement, studied primarily through indirect observations (e.g., seismic event parameters, seismic profiles, shipboard bathymetry, coring) rather than direct ones. Using deep-sea vehicles, we identify for the first time a marker of coseismic slip on a submarine fault plane along the Roseau Fault (Lesser Antilles), and measure its vertical displacement of ∼0.9 m in situ. We also map recent fissuring and faulting of sediments on the hangingwall, along ∼3 km of rupture in close proximity to the fault's base, and document the reactivation of erosion and sedimentation within and downslope of the scarp. These deformation structures were caused by the 2004 M w 6.3 Les Saintes earthquake, which triggered a subsequent tsunami. Their characterization informs estimates of earthquake recurrence on this fault and provides new constraints on the geometry of fault rupture, which is both shorter and displays locally larger coseismic displacements than available model predictions that lack field constraints. This methodology of detailed field observations coupled with near-bottom geophysical surveying can be readily applied to numerous submarine fault systems, and should prove useful in evaluating seismic and tsunamigenic hazard in all geodynamic contexts.
Published: 2016
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19. Rapid spatiotemporal variations in rift structure during development of the Corinth Rift, central Greece

Author: Nixon, CW, Mcneill, LC, Bull, JM, Bell, RE, Gawthorpe, RL, Henstock, TJ, Christodoulou, D, Ford, M, Taylor, B, Sakellariou, D, Ferentinos, G, Papatheodorou, G, Leeder, MR, Collier, REL, Goodliffe, AM, Sachpazi, M, Kranis, H, National Oceanography Centre [Southampton] (NOC), University of Southampton, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Department of Earth Science and Technology [Imperial College London], Imperial College London, Department of Geology, University of Patras [Patras], 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), University of Hawai'i [Honolulu] (UH), Hellenic Center for Marine Research (HCMR), School of Environmental Sciences, University of East Anglia [Norwich] (UEA), School of Earth and Environment [Leeds] (SEE), University of Leeds, Department of Geological Sciences, University of South Alabama, National Observatory of Athens (NOA), Dynamic, Tectonic and Applied Geology, and National and Kapodistrian University of Athens (NKUA)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Antikyra Fault, paleoenvironment, Greece, Cenozoic, seismic stratigraphy, chronostratigraphy, geophysical surveys, seismic methods, faults, Galaxidi Fault, 0404 Geophysics, basin analysis, marine methods, Europe, geophysical methods, Pleistocene, 0403 Geology, Xylokastro Fault, Mediterranean Sea, Corinth Rift, reflection methods:sedimentation, Lykoporia Fault, depositional environment, temporal distribution
Abstract: International audience; The Corinth Rift, central Greece, enables analysis of early rift development as it is young (
Published: 2016
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20. The key role of topography in altering North Atlantic atmospheric circulation during the last glacial period

Author: Francesco S. R. Pausata, Masa Kageyama, Camille Li, Justin J. Wettstein, Kerim H. Nisancioglu, Geophysical Institute [Bergen] (GFI / BiU), University of Bergen (UiB), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Department of Earth Science [Bergen] (UiB), Oregon State University (OSU), 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), 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), and 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)
Subjects: 010504 meteorology & atmospheric sciences, Stratigraphy, lcsh:Environmental protection, Antarctic sea ice, 010502 geochemistry & geophysics, 01 natural sciences, lcsh:Environmental pollution, Sea ice, Cryosphere, lcsh:TD169-171.8, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, lcsh:Environmental sciences, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:GE1-350, Global and Planetary Change, geography, geography.geographical_feature_category, Paleontology, Last Glacial Maximum, Arctic ice pack, Ice-sheet model, 13. Climate action, Climatology, Sea ice thickness, lcsh:TD172-193.5, Ice sheet, Geology
Abstract: The Last Glacial Maximum (LGM; 21 000 yr before present) was a period of low atmospheric greenhouse gas concentrations, when vast ice sheets covered large parts of North America and Europe. Paleoclimate reconstructions and modeling studies suggest that the atmospheric circulation was substantially altered compared to today, both in terms of its mean state and its variability. Here we present a suite of coupled model simulations designed to investigate both the separate and combined influences of the main LGM boundary condition changes (greenhouse gases, ice sheet topography and ice sheet albedo) on the mean state and variability of the atmospheric circulation as represented by sea level pressure (SLP) and 200-hPa zonal wind in the North Atlantic sector. We find that ice sheet topography accounts for most of the simulated changes during the LGM. Greenhouse gases and ice sheet albedo affect the SLP gradient in the North Atlantic, but the overall placement of high and low pressure centers is controlled by topography. Additional analysis shows that North Atlantic sea surface temperatures and sea ice edge position do not substantially influence the pattern of the climatological-mean SLP field, SLP variability or the position of the North Atlantic jet in the LGM.
Published: 2011
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21. Multipurpose Acoustic Networks in the Integrated Arctic Ocean Observing System

Author: Henk Keers, John A. Orcutt, Agnieszka Beszczynska-Möller, Lee Freitag, Kathleen J. Vigness-Raposa, Jean-Claude Gascard, Sue E. Moore, Kathleen M. Stafford, Hanne Sagen, Peter F. Worcester, Timothy F. Duda, Craig M. Lee, Andrey K. Morozov, M. Arrott, Kuvvet Atakan, Arthur B. Baggeroer, Peter N. Mikhalevsky, Frank L. Vernon, Brian D. Dushaw, Michel Rixen, Emmanuel Skarsoulis, Walter Munk, Stein Sandven, Alexander Gavrilov, Mo Yan Yuen, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Austral, Boréal et Carbone (ABC), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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 Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institute of Gene Biology, Russian Academy of Sciences, World Meteorological Organization (WMO), Nansen Environmental and Remote Sensing Center [Bergen] (NERSC), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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 Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636))
Subjects: 0106 biological sciences, Sustainable development, Marine conservation, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Meteorology, 010604 marine biology & hydrobiology, Passive monitoring, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 7. Clean energy, 01 natural sciences, Oceanography, Arctic, 13. Climate action, Sea ice, Environmental science, 14. Life underwater, Underwater, Ecology, Evolution, Behavior and Systematics, Search and rescue, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Subsea
Abstract: The dramatic reduction of sea ice in the Arctic Ocean will increase human activities in the coming years. This activity will be driven by increased demand for energy and the marine resources of an Arctic Ocean accessible to ships. Oil and gas exploration, fisheries, mineral extraction, marine transportation, research and development, tourism, and search and rescue will increase the pressure on the vulnerable Arctic environment. Technologies that allow synoptic in situ observations year-round are needed to monitor and forecast changes in the Arctic atmosphere-ice-ocean system at daily, seasonal, annual, and decadal scales. These data can inform and enable both sustainable development and enforcement of international Arctic agreements and treaties, while protecting this critical environment. In this paper, we discuss multipurpose acoustic networks, including subsea cable components, in the Arctic. These networks provide communication, power, underwater and under-ice navigation, passive monitoring of ambient sound (ice, seismic, biologic, and anthropogenic), and acoustic remote sensing (tomography and thermometry), supporting and complementing data collection from platforms, moorings, and vehicles. We support the development and implementation of regional to basin-wide acoustic networks as an integral component of a multidisciplinary in situ Arctic Ocean observatory.
Published: 2015
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22. Does rift lateral propagation depend on climate and surface processes?

Author: Steer, Philippe, Huismans, Ritske, Cowie, P.A., Allken, V., Thieulot, Cédric, 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), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), 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 Dubigeon, Isabelle
Subjects: [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2014

23. Impact of lithosphere deformation onstratigraphic architecture of passive marginbasins

Author: Rouby, Delphine, Huismans, Ritske, Robin, Cecile, Braun, Jean, Al., Et, 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-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), 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), Tectonique reliefs et bassins, 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 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), 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), 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: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract: National audience; The aim of this study is to revise our view of the long-term stratigraphictrends of passive margins to include the impact of the coupling betweenthe lithosphere deformation and the surface processes. To do this, wedeveloped a new numerical procedure simulating interactions betweenlithosphere deformation and (un)loading effects of surface processes(erosion/sedimentation) in 3D with a special attention to the stratigraphicarchitecture of the associated sedimentary basins.We first simulatethe syn-rift phase of lithosphere stretching by thermo-mechanical modeling.We then use the resulting lithosphere geometry as input of a 3Dflexural modeling including coupling with surface processes to simulatethe post-rift evolution of the margin. We then use the resulting accumulationand subsidence histories as input of the stratigraphic simulation tomodel the detailed stratigraphic architecture of the basin. We tested thisprocedure using synthetic examples of lithosphere stretching based ondifferent rheologies of the lithosphere (i.e. strength of the lower crust) inthe cases of narrow or ultrawide rifting.We determined the stratigraphicexpression of the conjugate margins and show that they differ in termsof long-term stratigraphic trends, erosion/accumulation and lithologicaldistribution in space and time.In all cases, uplift/subisdence rates decrease with time while the flexurewavelength increases as isotherms are re-equilibrated. Some areas showdisplacement inversion over time from uplift to subsidence (or viceversa).As expected, the amplitude of vertical motion of the wide margincases is very limited with respect to the narrow margin case. Verticalmotions are very asymetric on conjugate margins. Accordingly, thestratigraphic architectures and the sedimentation/erosion patterns of theconjugate simulated margins are significantly different mostly becausethe duration and length of progradation and retrogradation differ. Weevaluated the sensitivity of the simulations to parameters controlling (i)the lithosphere deformation, (ii) the continental drainage erosivity (climate)or (iii) erodability (lithology) as well as (iv) base level (eustasy).
Published: 2014

24. Development of an incised valley-fill at an evolving rift margin: Pleistocene eustasy and tectonics on the southern side of the Gulf of Corinth, Greece

Author: Eivind Sjursen, Katarina Gobo, Wojciech Nemec, Massimiliano Ghinassi, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Dipartimento di Geoscienze [Padova], and Universita degli Studi di Padova
Subjects: Marine isotope stage, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Rift, Pleistocene, Stratigraphy, shoal-water delta, sequence stratigraphy, Gilbert-type delta, incised-valley system, relay ramp, sedimentary facies, sequence stratigraphy, shoal-water delta, Geology, sedimentary facies, Gilbert-type delta, incised-valley system, Paleontology, Tectonics, Facies, Interglacial, relay ramp, Sequence stratigraphy, Alluvium, 14. Life underwater
Abstract: International audience; This study from the southern margin of the Gulf of Corinth documents a Late Pleistocene incised valley-fill succession that differs from the existing facies models, because it comprises gravelly shoal-water and Gilbert-type deltaic deposits, shows strong wave influence and lacks evidence of tidal activity. The valley-fill is at least 140 m thick, formed in 50 to 100 ka between the inter-glacials Marine Isotope Stage 9a and Marine Isotope Stage 7c. The relative sea-level rise left its record both inside and outside the incised valley, and the age of the valley-fill is estimated from a U/Th date of coral-bearing deposits directly outside the palaeovalley outlet. Tectonic up-warping due to formation of a valley-parallel structural relay ramp contributed to the valley segmenta-tion and limited the landward extent of marine invasions. The valley segment upstream of the ramp crest was filled with a gravelly alluvium, whereas the downstream segment accumulated fluvio-deltaic deposits. The consecutive deltaic systems nucleated in the ramp-crest zone, forming a bathymetric gradient that promoted the ultimate growth of thick Gilbert-type delta. The case study contributes to the spectrum of conceptual models for incised valley-fill architecture. Four key models are discussed with reference to the rates of sediment supply and accommodation development, and it is pointed out that not only similarity, but also all departures of particular field cases from these end-member models may provide valuable information on the system formative conditions. The Akrata incised valley-fill represents conditions of high sediment supply and a rapid, but stepwise development of accommodation that resulted from the spatiotemporal evolution of normal faulting at the rift margin and overprinted glacioeustatic signals. This study adds to an understanding of valley-fill architecture and provides new insights into the Pleistocene tecto-nics and palaeogeography of the Corinth Rift margin.
Published: 2014
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25. Impact of lithosphere deformation on stratigraphic architecture of passive margin basins

Author: Rouby, Delphine, Huismans, Ritske, Braun, Jean, Robin, Cécile, Granjeon, Didier, 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), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Tectonique reliefs et bassins, 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 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), 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), IFP Energies nouvelles (IFPEN), 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-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), 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]Sciences of the Universe [physics]/Earth Sciences
Abstract: International audience; The aim of this study is to revise our view of the long-term stratigraphic trends of passive margins to include the impact of the coupling between the lithosphere deformation and the surface processes. To do this, we developed a new numerical procedure simulating interactions between lithosphere deformation and (un)loading effects of surface processes (erosion/sedimentation) in 3D with a special attention to the stratigraphic architecture of the associated sedimentary basins. We first simulate the syn-rift phase of lithosphere stretching by thermo-mechanical modeling. We then use the resulting lithosphere geometry as input of a 3D flexural modeling including coupling with surface processes to simulate the post-rift evolution of the margin. We then use the resulting accumulation and subsidence histories as input of the stratigraphic simulation to model the detailed stratigraphic architecture of the basin. We tested this procedure using synthetic examples of lithosphere stretching based on different rheologies of the lithosphere (i.e. strength of the lower crust) in the cases of narrow or ultrawide rifting. We determined the stratigraphic expression of the conjugate margins and show that they differ in terms of long-term stratigraphic trends, erosion/accumulation and lithological distribution in space and time. In all cases, uplift/subisdence rates decrease with time while the flexure wavelength increases as isotherms are re-equilibrated. Some areas show displacement inversion over time from uplift to subsidence (or vice-versa). As expected, the amplitude of vertical motion of the wide margin cases is very limited with respect to the narrow margin case. Vertical motions are very asymetric on conjugate margins. Accordingly, the stratigraphic architectures and the sedimentation/erosion patterns of the conjugate simulated margins are significantly different mostly because the duration and length of progradation and retrogradation differ. We evaluated the sensitivity of the simulations to parameters controlling (i) the lithosphere deformation, (ii) the continental drainage erosivity (climate) or (iii) erodability (lithology) as well as (iv) base level (eustasy).
Published: 2014

26. Feedback between surface processes and rift-passive margin formation

Author: Huismans, Ritske, Steer, Philippe, Cowie, P.A., Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), 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), Dubigeon, Isabelle, 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: [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2014

27. The Contribution of Paleoseismology to Earthquake Hazard Evaluations

Author: Mustapha Meghraoui, Kuvvet Atakan, Dynamique globale et déformation active (IPGS) (IPGS-DGDA), Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Max Wyss, and John F. Shroder
Subjects: Seismic gap, Seismic microzonation, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Earthquake prediction, seismic hazard, Paleoseismology, 010502 geochemistry & geophysics, 01 natural sciences, Earthquake scenario, Seismic hazard, Earthquake simulation, Intraplate earthquake, Types of earthquake, active faulting, fault parameters, Geology, Seismology, 0105 earth and related environmental sciences
Abstract: International audience; Paleoseismology is a relatively young method of earthquake studies at the interface between geology and seismology. Paleoseismic investigations have enriched the fault rupture database in some active zones (e.g., California, Turkey, Italy) and contribute to a significant progress in the concept of earthquake cycle. The increasing number of paleoseismic studies in the last decades was dedicated primarily to the major continental faults that experienced large earthquakes (Mw > 7). The validity of paleoseismic results was tested in regions with long historical catalogs and well-documented past earthquake ruptures as along the North Anatolian Fault and Dead Sea Fault. Major advances in the calculation of realistic earthquake hazard assessment are achieved when earthquake geology and paleoseismic data are available. Among case studies, the probabilistic seismic hazard assessment of the Istanbul (Turkey) region, based on earthquake scenarios revealed the influence of paleoseismic data on the ground motion equations. The integration of paleoseismology in earthquake hazard projects is, however , not yet systematic and consequently many earthquake hazard maps include large uncertainties and approximations. 10.1 INTRODUCTION Geological investigations applied to the study of past earthquakes are now at the forefront of seismological and seismic hazard research. Also known as paleoseismology, these investigations include the study of active faulting, seismites (sedimentary structures produced by shaking), liquefaction features, and other effects of earthquake shaking (e.g., rockfalls and landslides) that can be recorded in superficial geological units (Soloneko, 1973; McCalpin, 1996). The record of permanent earthquake deformation at the surface is essential in Earthquake Hazard, Risk, and Disasters. http://dx.
Published: 2014
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28. XMapTools: A MATLAB©-based program for electron microprobe X-ray image processing and geothermobarometry

Author: Olivier Vidal, Eric Lewin, Eugene G. Grosch, Pierre Lanari, Benoît Dubacq, Stéphane Schwartz, Vincent De Andrade, Institute of Geological Sciences [Bern], University of Bern, Institut des Sciences de la Terre (ISTerre), Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-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-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Brookhaven National Laboratory, SRX beamline, NSLS II, Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences [Cambridge, UK], University of Cambridge [UK] (CAM), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Centre for Geobiology [Bergen], and 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)
Subjects: Mineral, 010504 meteorology & atmospheric sciences, Geothermobarometry, Mineralogy, Ternary plot, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Electron microprobe, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, engineering, Plagioclase, Paragenesis, Computers in Earth Sciences, Omphacite, Amphibole, Geology, 0105 earth and related environmental sciences, Information Systems
Abstract: International audience; XMapTools is a MATLAB©-based graphical user interface program for electron microprobe X-ray image processing, which can be used to estimate the pressure-temperature conditions of crystallization of minerals in metamorphic rocks. This program (available online at http://www.xmaptools.com) provides a method to standardize raw electron microprobe data and includes functions to calculate the oxide weight percent compositions for various minerals. A set of external functions is provided to calculate structural formulae from the standardized analyses as well as to estimate pressure-temperature conditions of crystallization, using empirical and semi-empirical thermobarometers from the literature. Two graphical user interface modules, Chem2D and Triplot3D, are used to plot mineral compositions into binary and ternary diagrams. As an example, the software is used to study a high-pressure Himalayan eclogite sample from the Stak massif in Pakistan. The high-pressure paragenesis consisting of omphacite and garnet has been retrogressed to a symplectitic assemblage of amphibole, plagioclase and clinopyroxene. Mineral compositions corresponding to $165,000 analyses yield estimates for the eclogitic pressure-temperature retrograde path from 25 kbar to 9 kbar. Corresponding pressure- temperature maps were plotted and used to interpret the link between the equilibrium conditions of crystallization and the symplectitic microstructures. This example illustrates the usefulness of XMapTools for studying variations of the chemical composition of minerals and for retrieving information on metamorphic conditions on a microscale, towards computation of continuous pressure-temperature-and relative time path in zoned metamorphic minerals not affected by post-crystallization diffusion.
Published: 2014
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29. Three-dimensional numerical simulations of crustal systems undergoing orogeny and subjected to surface processes

Author: Philippe Steer, Cedric Thieulot, Ritske S. Huismans, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), 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), 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: Landscape evolution model, 010504 meteorology & atmospheric sciences, Deformation (mechanics), Elevation, Fluvial, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Orogeny, Geophysics, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Tectonics, numerical modeling, 13. Climate action, Geochemistry and Petrology, orogeny, Erosion, Erosion and tectonics, surface processes, Geology, 0105 earth and related environmental sciences
Abstract: International audience; As several modeling studies indicate, the structural expression and dynamic behavior of oro-genic mountain belts are dictated not only by their rheological properties or by far-field tectonic motion, but also by the efficiency of erosion and sedimentation acting on its surface. Until recently, numerical inves-tigations have been mainly limited to 2-D studies because of the high computational cost required by 3-D models. Here, we have efficiently coupled the landscape evolution model Cascade with the 3-D thermome-chanically coupled tectonics code FANTOM. Details of the coupling algorithms between both codes are given. We present results of numerical experiments designed to study the response of viscous-plastic crustal materials subjected to convergence and to surface processes including both erosion and sedimentation. In particular, we focus on the equilibration of both the tectonic structures and on the surface morphology of the orogen. We show that increasing the efficiency of fluvial erosion increases the frontal thrust angle, which in turn decreases the width of the orogen. In addition, the maximum summit elevation of the orogen during transient evolution is significantly higher in those models showcasing surface processes than those that do not. This illustrates the strong coupling between tectonics and surface processes. We also demon-strate that an along-strike gradient of erosion efficiency can have a major impact upon the landscape mor-phology and the tectonic structure and deformation of the orogen, in both the across-strike and along-strike directions. Overall, our results suggest that surface processes, by enhancing localization of deforma-tion, can act as a positive forcing to topographic building.
Published: 2014
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30. Viscous roots of active seismogenic faults revealed by geologic slip rate variations

Author: C. H. Scholz, Patience A. Cowie, J. Faure Walker, Philippe Steer, Gerald P. Roberts, 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 Science [Bergen] (UiB), University of Bergen (UiB), Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], School of Earth Sciences, Queen Mary University of London (QMUL), Institute for Risk and Disaster Reduction, University College of London [London] (UCL), 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), 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), and Dubigeon, Isabelle
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Slip (materials science), Active fault, Fault (geology), Strain rate, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Shear (geology), Lithosphere, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, General Earth and Planetary Sciences, Shear zone, Seismology, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Viscous flow at depth contributes to elastic strain accumulation along seismogenic faults during both post-seismic and inter-seismic phases of the earthquake cycle. Evaluating the importance of this contribution is hampered by uncertainties regarding (i) the extent to which viscous deformation occurs in shear zones or by distributed flow within the crust and/or upper mantle, and (ii) the value of the exponent, n, in the flow law that relates strain rate to applied stress. Geodetic data, rock deformation experiments, and field observations of exhumed (inactive) faults provide strong evidence for non-linear viscous flow but may not fully capture the long term, in situ behaviour of active fault zones. Here we demonstrate that strain rates derived from Holocene offsets on seismogenic normal faults in the actively uplifting and extending central and southern Italian Apennines may be used to address this issue. The measured strain rates, averaged over a time scale of 104 years, exhibit a well-defined power-law dependence on topographic elevation with a power-law exponent ≈ 3.0 (2.7 - 3.4 at 95% CI; 2.3 - 4.0 at 99% CI). Contemporary seismicity indicates that the upper crust in this area is at the threshold for frictional failure within an extensional stress field and therefore differential stress is directly proportional to elevation. Our data thus imply a relationship between strain rate and stress that is consistent with non-linear viscous flow, with n ≈ 3, but because the measurements are derived from slip along major crustal faults they do not represent deformation of a continuum. We know that, down-dip of the seismogenic part of active faults, cataclasis, hydrous alteration, and shear heating all contribute to grain size reduction and material weakening. These processes initiate localisation at the frictional-viscous transition and the development of mylonitic shear zones within the viscous regime. Furthermore, in quartzo-feldspathic crust, mylonites form a fabric of mineral segregated layers parallel to shear with their strength controlled by the weakest phase: quartz. Using a published flow law for wet quartz calibrated for mylonitic rocks to fit the strain rates across individual fault zones (~5 km wide), we estimate a lower bound on the temperature of the deforming material using our data. This temperature is reached at or just below the base of the seismogenic zone, as constrained by regional surface heat flow data and the depth distribution of crustal seismicity. We conclude that it is the rate of viscous flow in quartz-rich mylonitic shear zones, not distributed flow within the lower crust and/or upper mantle, which modulates the Holocene slip rates on the up-dip seismogenic part of the faults in this area. Our observations support the idea that the irregular, stick-slip movement of brittle faults, and hence earthquake recurrence, are ultimately modulated by down-dip viscous flow over multiple earthquake cycles.
Published: 2013
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31. Bimodal Plio-Quaternary glacial erosion of fjords and low-relief surfaces in Scandinavia

Author: Steer, Philippe, Huismans, Ritske, Valla, Pierre G., Gac, Sébastien, Herman, Frédéric, 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), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Geological Institute [ETH Zürich], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Institute of Earth Sciences, Université de Lausanne (UNIL), Dubigeon, Isabelle, 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 Université de Lausanne = University of Lausanne (UNIL)
Subjects: [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract: International audience; Glacial landscapes are characterized by dramatic local relief, but they also commonly exhibit high-elevation, lowreliefsurfaces. These surfaces have been attributed to glacial headward erosion and periglacial processes in Alpinesettings. However, the timing and processes responsible for their formation in northern high-latitude regions remainelusive. Here, we infer the topographic evolution of western Scandinavia during the Plio-Quaternary glaciations(0-2.8 Ma) by linking onshore erosion to offshore sedimentation. We estimate the rate of fjord erosion from geophysicalrelief and compare that with the erosion reflected by offshore sedimentation. We find that the sedimentsgenerated by fjord erosion (65-100 103 km3) over the entire western Scandinavia during the Plio-Quaternaryglaciations accounts for only 35–55% of the equivalent bedrock erosion deduced from total sediment volume depositedoff the coast of Norway. This large mismatch implies that during this period, significant erosion (300-400m) must have also taken place away from the fjords at high elevation and thus indicates a bimodal distribution ofglacial erosion. Furthermore, comparing the distribution of the high-elevation, low-relief surfaces with estimatesof the long-term glacier equilibrium line altitude supports the idea that effective erosion in extensively glaciatedareas limits topographic height, a process known as the glacial buzzsaw. We therefore conclude that glacial andperiglacial processes have a substantial impact on the formation of low-relief surfaces observed in glaciated mountainbelts and high-latitude continental margins.
Published: 2013

32. Quantifying long-term exhumation and glacial topographic evolution of the Sognefjord (western Scandinavia) using low-temperature thermochonometry

Author: Valla, Pierre, Herman, Frédéric, Shuster, David, Steer, Philippe, Lowick, Sally, Fellin, Giuditta, Huismans, Ritske, Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Geologisches Institut [ETH Zürich], Department of Earth and Planetary Science [UC Berkeley] (EPS), University of California [Berkeley], University of California-University of California, 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), Institute of Geology, University of Bern, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), 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 Dubigeon, Isabelle
Subjects: [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract: International audience; The high-relief landscapes around the coast of Scandinavia show a strong glacial imprint with spectacular glacial fjords surrounded by typically high-altitude low-relief surfaces [1,2]. These areas have been the subject of intense debate concerning the respective role of internal and external processes controlling the long-term exhumation history and topographic evolution [3-5]. One key issue relating to this debate is the presence of high-altitude, low-relief surfaces surrounded by strongly incised fjords. Some studies [3,4] relate these landscape features to remnants of Mesozoic "peneplanation" that were subsequently uplifted during the Cenozoic. As an alternative, others [5] propose that present-day topography results from slowly eroding Caledonian orogeny which has been subsequently rejuvenated during late-Cenozoic glaciations (carving deep fjords and shaping low-relief surfaces by preferential glacial/periglacial erosion around the ELA). A recent study [2] quantifying mass-balance between fjord erosion and offshore sedimentation volumes gave support to idea of recent glacial rejuvenation of the entire Scandinavian topography. There is to date, however, no direct quantitative constraint on both the age and the Cenozoic to present-day evolution of these surfaces, as well as the topographic evolution of deeply-incised fjords. In this study, we propose to use low-temperature thermochronometry ((U-Th-Sm)/He, 4He/3He and Luminescence thermochronometry) to obtain quantitative constraints on both the long-term exhumation and Late Cenozoic topographic evolution of the Sognefjord (western Scandinavia). The Sognefjord is the longest and deepest fjord of western Scandinavia, with up to ~2.8 km of local relief in its central part. It is surrounded by low-relief surfaces rising from ~400 m on the coast up to ~2000 m inland [1,2]. Published fission-track ages along the fjord are ~150-200 Ma, and fission-track lengths reveal a long residence time in the partial annealing zone [5,6]. We collected ~10 samples along the fjord bottom (where potential recent exhumation has been maximized), an elevation profile (~1km) in the outer part of the fjord, and sampled supplementary low-relief surfaces in the inner part. (U-Th-Sm)/He ages in the outer part of the Sognefjord are ~100-300 Ma, potentially very close or even older than fission-track ages in the area. Preliminary 4He/3He analyses reveal U-Th zonation in the apatites: laser-ablation ICP-MS analysis will be conducted to quantify the zonation effect in order to extract samples exhumation histories. A subset of bedrock samples (including fjord bottoms and low-relief surfaces) has been selected to perform feldspar Luminescence themochronometry [7]. With this novel and extremely low closure temperature method, we aim at quantifying the late-stage exhumation history and potential glacial impact on the Sognefjord topographic evolution. [1] Nesje & Whillans (1994). Geomorphology 9, 33-45. [2] Steer et al. (2012). Nat. Geosc. 5, 635-639. [3] Lidmar-Bergström et al. (2000). Change 24, 211-231. [4] Bonow et al. (2007). Norw. J. Geol. 87, 197-206. [5] Nielsen et al. (2012). J. Geodyn. 47, 72-95. [6] Hendriks et al. (2007). Norw. J. Geol. 87, 143-155. [7] Herman et al. (2010). Earth and Pla. Sci. Let. 297, 183-189.
Published: 2013

33. Feedback Between Surface Processes and Rift-Passive Margin Formation

Author: Huismans, Ritske, Steer, Philippe, Cowie, P.A., Kitterod, I., Dubigeon, Isabelle, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), 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), 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: [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract: International audience; We use new state of the art computational modeling techniques to model crust and lithosphere deformation coupled to surface processes in 2D and 3D. To date few 2D models exist that are able to bridge scales ranging from the lithosphere to sedimentary basin fill. Here we model in 2D the interaction of lithosphere deformation, high-resolution shear zone formation, and sedimentary basin fill. The models indicate a strong interaction and feedback between the structural style of deformation at crust and lithosphere scales and efficiency of sedimentary basin fill and rift flank erosion both in 2D and 3D. In 2D high deposition rates enhance rift localization and increase rift boundary fault offset. Rift flank erosion similarly enhance fault offset. We furthermore use large deformation 3D forward coupled tectonic-surface process modeling techniques to investigate the effect of surface process efficiency on rift linkage. The models indicate that the style of rift linkage in 3D is strongly controlled by fluvial surface process efficiency and by the amount of offset between pre-existing weakness zones.
Published: 2013

34. Control of lithosphere rheology on subduction polarity at initiation: Insights from 3D analogue modelling

Author: Ritske S. Huismans, Roy H. Gabrielsen, Ivar Midtkandal, Jean-Pierre Brun, Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Systèmes Tectoniques, 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 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), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Dubigeon, Isabelle, 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 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 Science [Bergen], and University of Bergen (UIB)
Subjects: 010504 meteorology & atmospheric sciences, Polarity (physics), [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Obduction, Geochemistry and Petrology, Lithosphere, Earth and Planetary Sciences (miscellaneous), Convergent boundary, Eclogitization, 0105 earth and related environmental sciences, Polarity reversal, Subduction, Cantabrians, Pyrenees, transfer zone, contraction, Geophysics, crocodile structure, Space and Planetary Science, Analogue modelling, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, subduction, Geology
Abstract: International audience; A series of analogue experiments was used to explore how lateral variations in lithosphere rheology may result in a subduction polarity reversal. Lithosphere models made of sand and silicone putty were designed to represent a plate convergence setting varying laterally from continent-continent to ocean-continent. Distinct series of experiments were performed to test the effects of strength profile variations in the converging plates. The modelling outcomes categorized into models that develop with and without a subduction polarity reversal. While a subduction polarity reversal was the most prevalent experiment outcome, the results suggest that upper mantle strength is the dominant factor in determining whether a subduction polarity shift occurs, or not. A weak upper mantle layer promotes obduction of the oceanic lithosphere in the western segment of the model. In model iterations where the upper mantle of the continental lithosphere was stronger than the oceanic lithosphere, a reversal in subduction polarity from north-dipping in the east, to south-dipping in the west occurred. The experiment design was inspired by the Iberian-Eurasian plate convergence and may provide a simple regional-scale explanation to the deformation patterns along the Pyrenean and Cantabrian orogeny.
Published: 2013
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35. Evidence for Storegga tsunami run-up at the head of Nordfjord, western Norway

Author: Vasskog, Kristian, Waldmann, Nicolas, Bondevik, Stein, Nesje, Atle, Chapron, Emmanuel, Ariztegui, Daniel, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Department of Marine Geosciences, University of Haifa [Haifa], Sogn og Fjordane University College, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-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)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Department of Earth and Environmental Sciences [Geneva], University of Geneva [Switzerland], and NORLAKE-project and the Centre for Climate Dynamics at the Bjerknes Centre for Climate Research, the SHIFTS-project (led by Professor Jostein Bakke at the University of Bergen), the University of Tromsø, the University of Geneva, the University of Orle'ans and ETH Zurich.
Subjects: Relative sea level change, Storegga tsunami, geohazards, [SDE.MCG]Environmental Sciences/Global Changes, Geohazards, lake sediments, western Norway, ddc:550, relative sea level change, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Western Norway, Lake sediments
Abstract: International audience; Numerical simulations show that the Storegga tsunami (∼8 150 cal a BP) penetrated into fjords and sounds along the Norwegian coast because of its large wavelengths of about 600-800 km. Despite this, deposits from the tsunami have not previously been reported from the innermost fjord district, probably because suitable sedimentary archives are lacking in the steep fjord landscape. Here we describe a persistent and well-defined depositional unit, up to 3 m thick, found in a lake sequence at the head of the 106-km-long Nordfjord, which we interpret as a deposit from the Storegga tsunami. The unit is identified and mapped in seismic profiles as a continuous semi-transparent unit which in places cut deeply into the underlying strata. In sediment cores the unit consists of grey silt with sub-units containing shell or plant fragments, gravel and sand clasts, and redeposited lake mud. Radiocarbon ages date the deposit to the time of the Storegga tsunami (∼8 150 cal a BP). We estimate a minimum run-up of 1-7.5 m for the tsunami based on the inferred elevation of the lake outlet relative to sea level at that time.
Published: 2013
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36. Mid-pliocene Atlantic Meridional Overturning Circulation not unlike modern

Author: Christian Stepanek, Daniel J. Lunt, Kerim H. Nisancioglu, Fran Bragg, Anne Jost, Gerrit Lohmann, Daniel J. Hill, Gilles Ramstein, Youichi Kamae, Aisling M. Dolan, Ayako Abe-Ouchi, Mark A. Chandler, Linda E. Sohl, Zhongshi Zhang, Nan Rosenbloom, Wing-Le Chan, Hiroaki Ueda, Bette L. Otto-Bliesner, Alan M. Haywood, Camille Contoux, Chinese Academy of Sciences [Beijing] (CAS), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Center for Climate Systems Research [New York] (CCSR), Columbia University [New York], School of Earth and Environment [Leeds] (SEE), University of Leeds, National Center for Atmospheric Research [Boulder] (NCAR), 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), 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), and 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)
Subjects: 010504 meteorology & atmospheric sciences, Atmospheric circulation, lcsh:Environmental protection, Stratigraphy, Climate change, 010502 geochemistry & geophysics, 01 natural sciences, Atlantic Equatorial mode, Meteorology and Climatology, lcsh:Environmental pollution, lcsh:TD169-171.8, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, lcsh:Environmental sciences, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, lcsh:GE1-350, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, North Atlantic Deep Water, Global warming, Paleontology, Marine Sciences, Oceanography, Shutdown of thermohaline circulation, 13. Climate action, Climatology, lcsh:TD172-193.5, Earth Sciences, Thermohaline circulation, Climate model, Geology
Abstract: In the Pliocene Model Intercomparison Project (PlioMIP), eight state-of-the-art coupled climate models have simulated the mid-Pliocene warm period (mPWP, 3.264 to 3.025 Ma). Here, we compare the Atlantic Meridional Overturning Circulation (AMOC), northward ocean heat transport and ocean stratification simulated with these models. None of the models participating in the PlioMIP simulates a strong mid-Pliocene AMOC as suggested by earlier proxy studies. Rather, there is no consistent increase in AMOC maximum among the PlioMIP models. The only consistent change in AMOC is a shoaling of the overturning cell in the Atlantic, and a reduced influence of North Atlantic Deep Water (NADW) at depth in the basin. Furthermore, the simulated mid-Pliocene Atlantic northward heat transport is similar to the pre-industrial. These simulations demonstrate that the reconstructed high latitude mid-Pliocene warming can not be explained as a direct response to an intensification of AMOC and concomitant increase in northward ocean heat transport by the Atlantic.
Published: 2013
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37. Deep structure of the central Lesser Antilles Island Arc: Relevance for the formation of continental crust

Author: Kopp, H., Weinzierl, W., Becel, A., Charvis, P., Evain, M., Flueh, E.R., Gailler, A., Galve, A., Hirn, A., Kandilarov, A., Klaeschen, D., Laigle, M., Papenberg, C., Planert, L., Roux, E., Thales And Trail, Teams, Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Géoazur (GEOAZUR 6526), Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, seismic tomography, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Oceanic plateau, 010502 geochemistry & geophysics, 01 natural sciences, Lesser Antilles margin, Geochemistry and Petrology, Oceanic crust, Earth and Planetary Sciences (miscellaneous), Convergent boundary, 14. Life underwater, Petrology, 0105 earth and related environmental sciences, Underplating, Subduction, Continental crust, crustal growth, island arc structure, Geophysics, 15. Life on land, oceanic subduction, 13. Climate action, Space and Planetary Science, Adakite, Island arc, pre-stack depth migration, Geology
Abstract: Oceanic island arcs are sites of high magma production and contribute to the formation of continental crust. Geophysical studies may provide information on the configuration and composition of island arc crust, however, to date only few seismic profiles exist across active island arcs, limiting our knowledge on the deep structure and processes related to the production of arc crust. We acquired active-source wide-angle seismic data crossing the central Lesser Antilles island arc north of Dominica where the oceanic Tiburon Ridge subducts obliquely beneath the forearc. A combined analysis of wide-angle seismics and pre-stack depth migrated reflection data images the complex structure of the backstop and its segmentation into two individual ridges, suggesting an intricate relation between subducted basement relief and forearc deformation. Tomographic imaging reveals three distinct layers composing the island arc crust. A three kilometer thick upper crust of volcanogenic sedimentary rocks and volcaniclastics is underlain by intermediate to felsic middle crust and plutonic lower crust. The island arc crust may comprise inherited elements of oceanic plateau material contributing to the observed crustal thickness. A high density ultramafic cumulates layer is not detected, which is an important observation for models of continental crust formation. The upper plate Moho is found at a depth of 24 km below the sea floor. Upper mantle velocities are close to the global average. Our study provides important information on the composition of the island arc crust and its deep structure, ranging from intermediate to felsic and mafic conditions. In this study we model the deep structure of the Lesser Antilles Island Arc. We use a hybrid analysis of refraction and reflection seismic data. We image the complex structure of two ridges forming the backstop. Island arc crust composition ranges from intermediate to felsic to mafic conditions. We discuss the formation of island arc and continental crust.
Published: 2011
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38. A Holocene record of snow-avalanche and flood activity reconstructed from a lacustrine sedimentary sequence in Oldevatnet, western Norway

Author: Daniel Ariztegui, Eivind Støren, Atle Nesje, Emmanuel Chapron, Nicolas Waldmann, Kristian Vasskog, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Institut Forel and Department of Geology and Paleontology, University of Geneva [Switzerland], and Université de Tours-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010506 paleontology, Archeology, density currents, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Sorting (sediment), western Norway, palaeoclimate, 01 natural sciences, Sedimentary depositional environment, ddc:550, Glacial period, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geomorphology, Holocene, 0105 earth and related environmental sciences, Earth-Surface Processes, Global and Planetary Change, geography, geography.geographical_feature_category, Ecology, Paleontology, Sediment, Glacier, Snow, proglacial lake sediments, 13. Climate action, floods, snow-avalanches, Sedimentary rock, Physical geography, Geology
Abstract: International audience; Two lacustrine sediment cores from Oldevatnet in western Norway have been studied in order to produce a record of floods, mass-wasting events and glacier fluctuations during the last 7300 years. River floods, density currents and snow-avalanches have deposited distinct 'event layers' at the lake floor throughout this time interval. In this study, a novel approach has been applied to distinguish event layers from the continuous background sedimentation, using Rb/Sr-ratios from X-Ray Fluorescence data. Grain-size distribution and the sedimentological parameters 'mean' and 'sorting' were used to further infer the depositional processes behind each layer. Our data suggest a record dominated by snow-avalanches, with the largest activity occurring during the 'Little Ice Age' (LIA). This increase in snow-avalanche activity observed during the LIA was probably caused by a combination of generally increasing winter precipitation and the advance of local glaciers towards the steep valley sides. Several fluctuations in snow-avalanche activity are also recognized prior to the LIA. Proxies of glacial activity from the background sediments indicate a similar development as earlier palaeoclimatic reconstructions from the area. It differs from previous reconstructions, however, by suggesting a lower glacial activity in the period from 2200 to 1000 cal. yr BP.
Published: 2011
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39. Subducting slabs: jellyfishes in the Earth mantle

Author: Loiselet, Christelle, Braun, Jean, Husson, Laurent, Le Carlier de Veslud, Christian, Thieulot, Cédric, Yamato, Philippe, Grudjic, Djordje, 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), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Department of Earth Sciences [Halifax], Dalhousie University [Halifax], Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut des Sciences de la Terre (ISTerre), 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)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Laboratoire de Planétologie et Géodynamique UMR6112 (LPG), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA), Department of Earth Science [Bergen], University of Bergen (UIB), Observatoire des Sciences de l'Univers de Grenoble [1985-2015] (OSUG [1985-2015]), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut des Sciences de la Terre [2011-2015] (ISTerre [2011-2015]), 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)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Centre National de la Recherche Scientifique (CNRS), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, mantle stratification, slab viscosity, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, seismic tomography, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], subduction
Abstract: International audience; The constantly improving resolution of geophysical data, seismic tomography and seismicity in particular, shows that the lithosphere does not subduct as a slab of uniform thickness but is rather thinned in the upper mantle and thickened around the transition zone between the upper and lower mantle. This observation has traditionally been interpreted as evidence for the buckling and piling of slabs at the boundary between the upper and lower mantle, where a strong contrast in viscosity may exist and cause resistance to the penetration of slabs into the lower mantle. The distribution and character of seismicity reveal, however, that slabs undergo vertical extension in the upper mantle and compression near the transition zone. In this paper, we demonstrate that during the subduction process, the shape of low viscosity slabs (1 to 100 times more viscous than the surrounding mantle) evolves toward an inverted plume shape that we coin jellyfish. Results of a 3D numerical model show that the leading tip of slabs deform toward a rounded head skirted by lateral tentacles that emerge from the sides of the jellyfish head. The head is linked to the body of the subducting slab by a thin tail. A complete parametric study reveals that subducting slabs may achieve a variety of shapes, in good agreement with the diversity of natural slab shapes evidenced by seismic tomography. Our work also suggests that the slab to mantle viscosity ratio in the Earth is most likely to be lower than 100. However, the sensitivity of slab shapes to upper and lower mantle viscosities and densities, which remain poorly constrained by independent evidence, precludes any systematic deciphering of the observations.
Published: 2010
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40. Surface and subsurface seawater temperature reconstruction using Mg/Ca microanalysis of planktonic foraminifera Globigerinoides ruber, Globigerinoides sacculifer, and Pulleniatina obliquiloculata

Author: Sadekov, Aleksey, Eggins, Stephen, De Deckker, Patrick, Ninnemann, Ulysses, Kuhnt, Wolfgang, Bassinot, Franck, Research School of Earth Sciences [Canberra] (RSES), Australian National University (ANU), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Institut für Geowissenschaften [Kiel], Christian-Albrechts-Universität zu Kiel (CAU), 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), Paléocéanographie (PALEOCEAN), 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), 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), and 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)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract: International audience; [1] Laser-ablation inductively coupled plasma-mass spectrometry microanalyses of Mg/Ca across individual final chambers of three planktonic foraminifera species, Globigerinoides ruber, G. sacculifer, and Pulleniatina obliquiloculata, reveal significant interspecies differences in test Mg concentrations. Whereas these three species have similar Mg/Ca values at low sea surface temperatures ($22°C), they diverge markedly at high sea surface temperatures ($29°C). Explanations for these differences in species Mg/Ca values based on detailed comparison of species intratest Mg/Ca distributions suggest that compositional variability within tests cannot account for the observed deviation of species Mg/Ca values in warm-water equatorial regions. Multiple regression modeling and d 18 O analysis of Globigerinoides sacculifer tests indicate that interspecies differences in Mg/Ca values result from different depth habitats. The average Mg/Ca values of G. ruber final chambers reflect the temperature of the surface mixed layer (0-25 m), whereas those of G. sacculifer and Pulleniatina obliquiloculata correlate best with subsurface temperatures at 50-75 m and 100-125 m water depths, respectively. Mg/Ca calibration to the temperatures at these depths reveals a similar temperature control on Mg test composition in all species. Combining our results with Mg/Ca values from published culturing experiments, we derive a generalized equation for the effect of temperature and seawater salinity on foraminiferal Mg/Ca. We also show that the Mg/Ca composition of specific calcite layers within foraminiferal tests, including the low-Mg/Ca layers of Globigerinoides ruber and G. sacculifer and the cortex layer of Pulleniatina obliquiloculata, correlates with seawater temperature and can be used as an additional proxy for seawater temperature. Citation: Sadekov, A., S. M. Eggins, P. De Deckker, U. Ninnemann, W. Kuhnt, and F. Bassinot (2009), Surface and subsurface seawater temperature reconstruction using Mg/Ca microanalysis of planktonic foraminifera Globigerinoides ruber, Globigerinoides sacculifer, and Pulleniatina obliquiloculata, Paleoceanography, 24, PA3201
Published: 2009
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41. Influence of surrounding plates on 3D subduction dynamics

Author: Yamato, Philippe, Husson, Laurent, Braun, Jean, Loiselet, Christelle, Thieulot, Cédric, 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), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, plates kinematics, subduction
Abstract: International audience; Our 3D modelling study shows that the presence of lithospheric plates around a subducting plate has a significant influence on subduction dynamics, in particular on trench retreat rate, slab dip, and lateral shortening of the subducting plate. Neighbouring plates prevent unrealistic plate behaviour with no need for complex rheologies. Because, at the Earth's surface, plates form a continuous shell, they should not be neglected.
Published: 2009
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42. Petrogenesis of crustal wehrlites in the Oman ophiolite: Experiments and natural rocks

Author: Koepke, J., Schoenborn, S., Oelze, M., Wittmann, H., Feig, S. T., Hellebrand, E., Boudier, Françoise, Schoenberg, R., Institut für Mineralogie [Hannover], Leibniz Universität Hannover [Hannover] (LUH), ARC Centre of Excellence in Ore Deposits (CODES), University of Tasmania [Hobart, Australia] (UTAS), Department of Geology and Geophysics [Mānoa], University of Hawai‘i [Mānoa] (UHM), 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), Centre for Geobiology [Bergen], University of Bergen (UiB), and Department of Earth Science [Bergen] (UiB)
Subjects: experimental petrology, hydrous magmatism, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, 550 - Earth sciences, wehrlites, oceanic crust, Oman ophiolite
Abstract: International audience; In the Wadi Haymiliyah of the Oman ophiolite (Haylayn block), discordant wehrlite bodies ranging in size from tens to hundreds of meters intrude the lower crust at different levels. We combined investigations on natural wehrlites from the Wadi Haymiliyah section with an experimental study on the phase relations in a wehrlitic system in order to constrain the petrogenesis of the crustal wehrlites of the Oman ophiolite. Secondary ion mass spectrometry analyses of clinopyroxenes from different wehrlite bodies imply that the clinopyroxenes were crystallized from tholeiitic, mid-ocean ridge (MORB)-type melts. The presence of primary magmatic amphiboles in some wehrlites suggests a formation under hydrous conditions. Significantly enhanced Sr-87/Sr-86 isotope ratios of separates from these amphiboles imply that the source of the corresponding magmatic fluids was either seawater or subduction zone-related. The experiments revealed that under wet conditions at relatively low temperatures, a MORB magma has the potential to produce wehrlite in the ocean crust by accumulation of early olivine and clinopyroxene. These show typically high Mg# which is a consequence of the oxidizing effect of the prevailing high aH(2)O. First plagioclases crystallizing after clinopyroxene under wet conditions are high in An content, in contrast to the corresponding dry system. Trace element compositions of clinopyroxenes of those wehrlites from the Moho transition zone are too depleted in HREE to be in equilibrium with present-day MORB, implying a genetic relation to the V2 lavas of the Oman ophiolite, which are interpreted to be the result of fluid-enhanced melting of previously depleted mantle. We present a model on the petrogenesis of the crustal wehrlites in an upper mantle wedge above an initial, shallow subduction zone at the beginning of the intraoceanic thrusting.
Published: 2009
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43. Dependence of displacement-length scaling relations for fractures and deformation bands on the volumetric changes across them

Author: Donald M. Reeves, Roger Soliva, Chris H. Okubo, Richard A. Schultz, Haakon Fossen, Department of Geological Sciences and Engineering [Reno], University of Nevada [Reno], 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), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), US Geological Survey [Flagstaff], United States Geological Survey [Reston] (USGS), and Desert Research Institute (DRI)
Subjects: Shearing (physics), [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, strike-slip faults, deformation bands, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, scaling, Geology, Geometry, Strain energy density function, Cataclastic rock, strain-energy density, 010502 geochemistry & geophysics, 01 natural sciences, Lodeve permian basin, Fracture toughness, Discontinuity (geotechnical engineering), Shear (geology), compaction bands, Deformation bands, Geotechnical engineering, Scaling, faulting, 0105 earth and related environmental sciences
Abstract: Displacement-length data from faults, joints, veins, igneous dikes, shear deformation bands, and compaction bands define two groups. The first group, having a power-law scaling relation with a slope of n = 1 and therefore a linear dependence of maximum displacement and discontinuity length (D-max = gamma L), comprises faults and shear (non-compactional or non-dilational) deformation bands. These shearing-mode structures, having shearing strains that predominate over volumetric strains across them, grow under conditions of constant driving stress, with the magnitude of near-tip stress on the same order as the rock's yield strength in shear. The second group, having a power-law scaling relation with a slope of n = 0.5 and therefore a dependence of maximum displacement on the square root of discontinuity length (D-max = alpha L-0.5), comprises joints, veins, igneous dikes, cataclastic deformation bands, and compaction bands. These opening- and closing-mode structures grow under conditions of constant fracture toughness, implying significant amplification of near-tip stress within a zone of small-scale yielding at the discontinuity tip. Volumetric changes accommodated by grain fragmentation, and thus control of propagation by the rock's fracture toughness, are associated with scaling of predominantly dilational and compactional structures with an exponent of n = 0.5.
Published: 2008
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44. Reduced north Atlantic deep water coeval with the glacial lake Agassiz freshwater outburst

Author: Catherine Kissel, Ulysses S Ninnemann, Helga F Kleiven, Elsa Cortijo, Carlo Laj, Thomas Richter, University of Bergen (UiB), 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), Climat et Magnétisme (CLIMAG), 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), Department of Earth Science [Bergen] (UiB), Royal Netherlands Institute for Sea Research (NIOZ), Paléocéanographie (PALEOCEAN), 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), and 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)
Subjects: [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Multidisciplinary, 010504 meteorology & atmospheric sciences, North Atlantic Deep Water, Ocean current, 010502 geochemistry & geophysics, 01 natural sciences, Gulf Stream, Atlantic Equatorial mode, Oceanography, Shutdown of thermohaline circulation, 13. Climate action, Thermohaline circulation, 14. Life underwater, Glacial lake, Holocene, 0105 earth and related environmental sciences
Abstract: An outstanding climate anomaly 8200 years before the present (B.P.) in the North Atlantic is commonly postulated to be the result of weakened overturning circulation triggered by a freshwater outburst. New stable isotopic and sedimentological records from a northwest Atlantic sediment core reveal that the most prominent Holocene anomaly in bottom-water chemistry and flow speed in the deep limb of the Atlantic overturning circulation begins at approximately 8.38 thousand years B.P., coeval with the catastrophic drainage of Lake Agassiz. The influence of Lower North Atlantic Deep Water was strongly reduced at our site for approximately 100 years after the outburst, confirming the ocean's sensitivity to freshwater forcing. The similarities between the timing and duration of the pronounced deep circulation changes and regional climate anomalies support a causal link.
Published: 2008
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45. Influence of instruments on the H/V spectral ratios of ambient vibrations

Author: Stratos Zacharopoulos, Paula Teves-Costa, Bertrand Guillier, Kuvvet Atakan, Jean-Luc Chatelain, Anne-Marie Duval, Jens Havskov, Fabrizio Cara, Matthias Ohrnberger, Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Institut für Geowissenschaften, Universität Potsdam, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, ERA 6 Risque sismique (ERA 6 Risque sismique - Equipe recherche associée au LCPC), Avant création Cerema, Institute of Engineering Seismology (ITSAK), Institute of Engineering Seismology, ICTE-UL, ICTE, Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), 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)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Department of Earth Science [Bergen], and University of Bergen (UIB)
Subjects: Microtremors, Engineering, Frequency band, Acoustics, Instrumentation, 0211 other engineering and technologies, Site effects, H/V technique, 02 engineering and technology, Seismic noise, 010502 geochemistry & geophysics, 01 natural sciences, Signal, Signal-to-noise ratio, Electronic engineering, Waveform, 0105 earth and related environmental sciences, Civil and Structural Engineering, instrumentation, 021110 strategic, defence & security studies, HV technique, business.industry, Building and Construction, Geotechnical Engineering and Engineering Geology, microtremors, Geophysics, [SDU]Sciences of the Universe [physics], site effects, Ground noise, business, Sensitivity (electronics)
Abstract: International audience; For an optimal analysis of the H/V curve, it appears necessary to check the instrument signal to noise ratio in the studied frequency band, to ensure that the signal from the ground noise is well above the internal noise. We assess the reliability and accuracy of various digitizers, sensors and/or digitizer-sensor couples. Although this study is of general interest for any kind of seismological study, we emphasize the influence of equipment on H/V analysis results. To display the impact of the instrumental part on the H/V behavior, some series of tests have been carried out following a step-by-step procedure: first, the digitizers have been tested in the lab (sensitivity, internal noise...), then the three components sensors, still in the lab, and finally the usual user digitizers-sensors couple in lab and outdoors. In general, the digitizer characteristics, verified during this test, correspond well to the manufacturer specifications, however, depending on the digitizer, the quality of the digitized waveform can be very good to very poor, with variation from a channel to another channel (gain, time difference etc.). It appears very clearly that digitizers need a warming up time before the recording to avoid problems in the low-frequency range. Regarding the sensors, we recommend strongly to avoid the use of “classical” accelerometers (i.e., usual force balance technology). The majority of tested seismometers (broadband and short period, even 4.5 Hz) can be used without problems from 0.4 to 25 Hz. In all cases, the instrumentation should be checked first to verify that it works well for the defined study aim, but also to define its limit of use (frequency, sensitivity...).
Published: 2008
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46. Response to 'Freshwater forcing: Will history repeat itself?'

Author: Flesche Kleiven, Kikki Helga, Kissel, Catherine, Laj, Carlo, S. Ninnemann, Ulysses, O. Richter, Thomas, Cortijo, Elsa, Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), Climat et Magnétisme (CLIMAG), 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), Royal Netherlands Institute for Sea Research (NIOZ), Paléocéanographie (PALEOCEAN), 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), and 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)
Subjects: [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, [SDE]Environmental Sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2008
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47. An abrupt change in the African monsoon at the end of the Younger Dryas

Author: R. Talbot, Michael, Letizia Filippi, Maria, Bo Jensen, Niels, Tiercelin, Jean-Jacques, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Museo Tridentino Scienze Naturali, IRIS Research, Domaines Océaniques (LDO), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, [SDE.MCG]Environmental Sciences/Global Changes, parasitic diseases, Limnology, Continental climate records
Abstract: International audience; High-resolution studies of variations in the elemental and stable carbon- and nitrogen-isotope composition of organic matter in cores from Lakes Malawi, Tanganyika, and Bosumtwi (tropical Africa) indicate an abrupt change in the wind-driven circulation of these lakes that, within the limits of available chronologies, was contemporaneous with the end of the Younger Dryas in the northern hemisphere. The change was also coincident with shifts in surface winds recorded in cores from off the west and northeast coasts of Africa. A range of other proxies indicate that these changes in wind regime were accompanied by a marked increase in precipitation in the northern tropics. Africa south of ~5°-10°S, on the other hand, initially suffered drought conditions. Together, the evidence suggests an abrupt northward translation of the African monsoon system at circa 11.5 ± 0.25 ka B.P. The data assembled here contribute to a growing body of work showing that the Younger Dryas was a major climatic excursion in tropical Africa. Furthermore, they add substance to recent suggestions that climatic events in the southern hemisphere may have played a significant role in the abrupt demise of the Younger Dryas
Published: 2007
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48. Evaluation of the influence of experimental conditions on H/V results from ambient noise recordings

Author: Anne-Marie Duval, Bertrand Guillier, Pierre-Yves Bard, Kuvvet Atakan, Fabrizio Cara, Jean-Luc Chatelain, Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, ERA 6 Risque sismique (ERA 6 Risque sismique - Equipe recherche associée au LCPC), Avant création Cerema, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Laboratoire Central des Ponts et Chaussées (LCPC), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), 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)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Department of Earth Science [Bergen], and University of Bergen (UIB)
Subjects: Engineering, Acoustics, Ambient noise level, 0211 other engineering and technologies, Site effects, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, microtremor, 02 engineering and technology, 010502 geochemistry & geophysics, 01 natural sciences, Stability (probability), Data acquisition, Microtremor, field conditions, Reliability (statistics), Simulation, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Civil and Structural Engineering, Reproducibility, Data processing, Data collection, business.industry, Measurements, Building and Construction, Fundamental frequency, Geotechnical Engineering and Engineering Geology, Geophysics, [SDU]Sciences of the Universe [physics], site effects, Field conditions, measurements, business
Abstract: International audience; The H/V-noise technique is now widely used to estimate site effect parameters (fundamental frequency and sometimes the associated soil amplification), and many surveys using this technique have provided convincing results. However, a general agreement on a methodology for data acquisition, data processing and result interpretation has yet to be found. H/V measurements from ambient noise recordings imply both reliability of the results and rapidity of data collection. It is therefore important to understand which experimental conditions (1) influence data quality and reliability, and (2) can help speeding up the recording process. Within the framework of the SESAME European project, a specific task was defined to investigate the reliability of the H/V spectral ratio technique in assessing the site effects. The aim of WP02, one specific Work Package of the SESAME project, is to study the effects of experimental conditions on both stability and reproducibility of H/V results. This study has been conducted in a purely experimental way, by testing the possible influence of various experimental conditions on H/V results both on the frequency peak value and on its amplitude. WP02 results help setting up the experimental conditions under which ambient noise recordings have to be performed in order to provide reproducible, reliable and meaningful H/V results. In this paper we present the results of the WP02 SESAME project concerning the evaluation of the influence of experimental conditions of ambient noise recording on H/V results.
Published: 2007
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49. Modelling the thermal evolution of slow-spreading ridge segments and their off-axis geophysical signature

Author: Jérôme Dyment, Sébastien Gac, Jean Goslin, Chantal Tisseau, Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut d'écologie et environnement-Observatoire des Sciences de l'Univers-Université de Brest (UBO)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Earth Science, University of Bergen (UIB), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), and Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: geography, Offset (computer science), geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Mid-ocean ridge, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Geophysics, Geodesy, 01 natural sciences, Gravity anomaly, Mantle (geology), 010305 fluids & plasmas, Geochemistry and Petrology, Lithosphere, 0103 physical sciences, Segmentation, Magnetic anomaly, Geology, Bouguer anomaly, 0105 earth and related environmental sciences
Abstract: International audience; Systematic studies conducted between 15°N and 40°N over ridge segments along the slow-spreading Mid-Atlantic Ridge (MAR) have shown that segment characteristics are related to the thermal state of the segments and gradually vary with their length. This paper presents further developments of a 3-D model, based on the presence of a hot zone located under the segment centres (Gac et al. 2003), to (1) quantify the thermal structures and the geophysical signatures of segments of various lengths, considered as representative of the various MAR segments; (2) test if a simple and single model of thermal evolution can account for the characteristics of all segments and (3) explain the past evolution of the segmentation, as is observed off-axis along the MAR. The modelled thermal structure and three simulated geophysical outputs [crustal structure , along-axis variations of the earthquake maximum depth and the mantle Bouguer gravity anomalies (MBA)] are found to be directly controlled by the shape (geometry and dimensions) of the hot zone. A consistent fit between model outputs and along-axis variations of the geophysical observables over the various segments is obtained by varying solely the length of the hot zone. This result shows that segments of different length may in fact constitute the different stages of a single evolution process: the axial geophysical characteristics of the segment would progressively evolve from those of shorter segments to those of longer ones, as the hot zone lengthens along-axis. A subsequent shortening of the segment would result from a simultaneous shortening of the hot zone, segment characteristics reverting back from those of longer segments to those of shorter ones. Three geophysical fields (topography, gravity and magnetic anomalies) are simulated as the results of the thermal evolution of aligned and offset segments the length of which evolves through time. These simulations succeed in fitting observations for the entire range of observed axis offsets between adjacent MAR segments. The segment evolution produces peculiar off-axis isostatic topography and gravity anomaly (MBA), the rhomb-shaped patterns. Our simulations, which model adjacent offset segments having evolved through several cycles of lengthening and shortening, yield a good fit to the isostatic topography and MBA patterns observed in the off-axis region. Finally, the distribution of magnetization depends on the magnetic properties of each type of rocks and on the petrological structure of the lithosphere, which, in turn, results from its thermal structure and evolution. Modelled magnetic anomalies are shown to be in good agreement with off-axis observations along the N21°40' segment (TAMMAR) of the MAR.
Published: 2006
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50. Local site effects in Ataköy, Istanbul, Turkey, due to a future large earthquake in the Marmara Sea

Author: Kuvvet Atakan, Nelson Pulido, Mathilde B. Sørensen, Çağlar Yalçıner, Ivo Oprsal, Sylvette Bonnefoy-Claudet, P. Martin Mai, Department of Earth Science [Bergen] (UiB), University of Bergen (UiB), Institute of Geophysics [ETH Zürich], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS), Earthquake Disaster Mitigation Research Center (EDM), Japan Earthquake Disaster Mitigation Research Center, Osmangazi University, 2.6 Seismic Hazard and Stress Field, 2.0 Physics of the Earth, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, Department of Earth Science [Bergen], University of Bergen (UIB), Institute of Geophysics, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), and 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)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)
Subjects: 010504 meteorology & atmospheric sciences, Wave propagation, Ambient noise level, 550 - Earth sciences, 010502 geochemistry & geophysics, 01 natural sciences, Synthetic data, Geochemistry and Petrology, Aegean Sea, Aftershock, 0105 earth and related environmental sciences, Earthquakes, Fault model, Finite-difference methods, Hybrid method, Istanbul, Strong ground motion, extensional tectonics, aftershocks, focal mechanisms, Geophysics, Seismic hazard, 13. Climate action, [SDU]Sciences of the Universe [physics], conjugate faulting, western Anatolia, Microtremor, Geology, Seismology
Abstract: International audience; Since the 1999 Izmit and Düzce earthquakes in northwest Turkey, many seismic hazard studies have focused on the city of Istanbul. An important issue in this respect is local site effects: strong amplifications are expected at a number of locations due to the local geological conditions. In this study we estimate the local site effects in the Ataköy area (southwestern Istanbul) by applying several techniques using synthetic data (hybrid 3-D modelling and 1-D modelling) and comparing to empirical data. We apply a hybrid 3-D finite-difference method that combines a complex source and wave propagation for a regional 1-D velocity model with site effects calculated for a local 3-D velocity structure. The local velocity model is built from geological, geotechnical and geomorphological data. The results indicate that strongest spectral amplifications (SA) in the Ataköy area occur around 1 Hz and that amplification levels are largest for alluvial sites where SA reaching a factor of 1.5-2 can be expected in the case of a large earthquake. We also compare our results to H/V (horizontal to vertical component of the recorded signal) spectral ratios calculated for microtremor data recorded at 30 sites as well as to ambient noise synthetics simulated using a 1-D approach. Because the applied methods complement each other, they provide comprehensive and reliable information about the local site effects in Ataköy. Added to that, our results have significant implications for the southwestern parts of Istanbul built on similar geological formations, for which, therefore, similar SA levels are expected.
Published: 2006
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