Viser treff 141-160 av 729

    • Digitising Svalbard’s geology: the Festningen digital outcrop model 

      Senger, Kim; Betlem, Peter; Birchall, Thomas; Gonzaga Jr., Luis; Grundvåg, Sten-Andreas; Horota, Rafael Kenji; Laake, Andreas; Kuckero, Lilith; Mørk, Atle; Planke, Sverre; Rodes, Nil; Smyrak-Sikora, Aleksandra (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-10)
      The renowned Festningen section in the outer part of Isfjorden, western Spitsbergen, offers a c. 7 km-long nearly continuous stratigraphic section of Lower Carboniferous to Cenozoic strata, spanning nearly 300 million years of geological history. Tectonic deformation associated with the Paleogene West-Spitsbergen-Fold-and-Thrust belt tilted the strata to near-vertical, allowing easy access to the ...
    • An annual profile of the impacts of simulated oil spills on the Northeast Arctic cod and haddock fisherie 

      Carroll, JoLynn; Frøysa, Håvard Guldbrandsen; Vikebø, Frode Bendiksen; Broch, Ole Jacob; Nepstad, Raymond; Augustine, Starrlight; Skeie, Geir Morten; Bockwoldt, Mathias; Howell, Daniel (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-10)
      We simulate the combined natural and pollutant-induced survival of early life stages of NEA cod and haddock, and the impact on the adult populations in response to the time of a major oil spill in a single year. Our simulations reveal how dynamic ocean processes, controlling both oil transport and fate and the frequency of interactions of oil with drifting fish eggs and larvae, mediate the magnitude ...
    • Hot Vents Beneath an Icy Ocean: The Aurora Vent Field, Gakkel Ridge, Revealed 

      Ramirez-Llodra, Eva; Argentino, Claudio; Baker, Maria; Boetius, Antje; Costa, Carolina; Dahle, Håkon; Denny, Emily Maria; Dessandier, Pierre-Antoine; Eilertsen, Mari Heggernes; Ferré, Benedicte; German, Cristopher R.; Hand, Kevin; Hilário, Ana; Hislop, Lawrence; Jamieson, John W.; Kalnitchenko, Dimitri; Mall, Achim; Panieri, Giuliana; Purser, Autun; Ramalho, Sofia P.; Reeves, Eoghan P.; Rolley, Leigthon; Pereira, Samuel I.; Ribeiro, Pedro A.; Sert, Muhammed Fatih; Steen, Ida H.; Stetzler, Marie; Stokke, Runar; Victorero, Lissette; Vulcano, Francesca; Vågenes, Stig; Waghorn, Kate Alyse; Buenz, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-28)
      Evidence of hydrothermal venting on the ultra-slow spreading Gakkel Ridge in the Central Arctic Ocean has been available since 2001, with first visual evidence of black smokers on the Aurora Vent Field obtained in 2014. But it was not until 2021 that the first ever remotely operated vehicle (ROV) dives to hydrothermal vents under permanent ice cover in the Arctic were conducted, enabling the ...
    • The extreme yet transient nature of glacial erosion 

      Patton, Henry; Hubbard, Alun; Heyman, J.; Alexandropoulou, Nikolitsa; Lasabuda, Amando P. E.; Stroeven, A.P.; Hall, A.M.; Winsborrow, Monica; Sugden, David E.; Kleman, J.; Andreassen, Karin Marie (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-30)
      Ice can sculpt extraordinary landscapes, yet the efficacy of, and controls governing, glacial erosion on geological timescales remain poorly understood and contended, particularly across Polar continental shields. Here, we assimilate geophysical data with modelling of the Eurasian Ice Sheet — the third largest Quaternary ice mass that spanned 49°N to 82°N — to decipher its erosional footprint during ...
    • Multiproxy investigation of the last 2,000 years BP marine paleoenvironmental record along the western Spitsbergen margin 

      Torricella, Fiorenza; Gamboa Sojo, Viviana Maria; Gariboldi, Karen; Douss, Nessim; Musco, Maria Elena; Caricchi, Chiara; Lucchi, Renata Giulia; Carbonara, Katia; Morigi, Caterina (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-01)
      A reconstruction of the last 2,000 years BP of environmental and oceanographic changes on the western margin of Spitsbergen was performed using a multidisciplinary approach including the fossil assemblages of diatoms, planktic and benthic foraminifera and calcareous nannofossils and the use of geochemistry (X-ray fluorescence spectroscopy, X-ray diffraction). We identified two warm periods ...
    • Quartz rheology constrained from constant-load experiments: Consequences for the strength of the continental crust 

      Ghosh, Subhajit; Stunitz, Holger; Raimbourg, Hugues; Précigout, Jacques (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-21)
      The mechanical properties of quartz are fundamental to control the plastic behaviour of the continental crust. Our understanding of quartz rheology is still limited in the following respects: i) the large variability of flow law parameters in the earlier literature (stress exponent n = 4 to ≤ 2 and activation energy Q = 120 to 242 kJ/mol), and ii) the difficulty to identify the rate-limiting deformation ...
    • Mechanical properties and recrystallization of quartz in presence of H<inf>2</inf>O: Combination of cracking, subgrain rotation and dissolution-precipitation processes 

      Pongrac, Petar; Jeřábek, Petr; Stunitz, Holger; Raimbourg, Hugues; Heilbronner, Renee; Racek, Martin; Nègre, Lucille (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-21)
      Natural quartzite samples, as-is and with 0.1 wt% of added H<sub>2</sub>O, have been deformed up to ∼30% bulk strain in axial shortening experiments with constant strain rate of ∼10<sup>−6</sup> s<sup>−1</sup> at 900 °C and 1 GPa, and in strain rate stepping ∼10<sup>−5</sup> to ∼10<sup>−7</sup> s<sup>−1</sup> at 900 °C and 1–1.5 GPa, in order to investigate the role of H<sub>2</sub>O in deformation ...
    • Late Quaternary terrigenous plant and coaly fragments found at Vestnesa Ridge, Fram Strait: implications for postglacial plant colonization at Svalbard 

      Hanken, Nils-Martin; Sztybor, Kamila; Høeg, Helge I.; Karlsen, Dag Arild; Rasmussen, Tine Lander; Abay, Tesfamariam Berhane (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-23)
      One of four marine cores of glacial sediments collected from a water depth of about 1200 m at Vestnesa Ridge (west of Svalbard) contained small fragments of coal, charcoal and moss. This material was restricted to a single level, and 14C dating of bivalves both above and below indicates an age of c. 18.0–15.5 kyr BP. Chemical analyses of the coal indicate that the provenance area was from the northern ...
    • Structural and fluid-migration control on hill-hole pair formation: Evidence from high-resolution 3D seismic data from the SW Barents Sea 

      Bellwald, Benjamin; Stokke, Henrik Henriksen; Winsborrow, Monica; Planke, Sverre; Sættem, Joar; Lebedeva-Ivanova, Nina; Hafeez, Amer; Kurjanski, Bartosz; Myklebust, Reidun Alice; Polteau, Stephane (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-11)
      Hill-hole pairs are subglacial landforms consisting of thrust-block hills and associated source depressions. Formed by evacuation of material where ice sheets have been locally frozen to the substrate, they give insights into paleo-ice-sheet dynamics. The aim of this study was to document the relationships between ancient hill-hole pairs identified on a buried glacial unconformity with the structure ...
    • Climatic impacts on an Arctic lake since 1300 AD: a multi-proxy lake sediment reconstruction from Prins Karls Forland, Svalbard 

      Orme, Lisa Claire; Lind, Ewa M.; Holm, Trine Marianne; Kjellman, Sofia Elisabeth; Koinig, Karin A.; Hormes, Anne; Rosqvist, Gunhild C.; Ruppel, Meri; Divine, Dmitry; Husum, Katrine; Miettinen, Arto; Isaksson, Elisabeth (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-31)
      On the remote Arctic archipelago of Svalbard, there is increasing evidence of environmental impacts from climate change. The analysis of lake sedimentary records can be used to assess how strongly these recent changes have altered lake ecosystems. Sediments deposited during the last millennium from Lake Blokkvatnet, Prins Karls Forland, were analysed using a multiproxy approach, including stable ...
    • Petrogenesis of zoned and unzoned mafic pegmatites: An insight from the Palaeoproterozoic mafic-ultramafic Hamn intrusion, Northern Norway 

      Heckmann, Paul; Strmic Palinkas, Sabina; Hansen, Harald; Iacono Marziano, Giada; Rajic, Kristijan; Forien, Melanie; Bergh, Steffen Gunnar (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-03)
      Mafic pegmatites have been reported from various geological environments, including ophiolites, layered magmatic intrusions, and volcanic arcs, but their petrogenesis stayed poorly constrained. This study brings new mineralogical and geochemical data obtained from unzoned and zoned gabbroic pegmatites hosted by the 1.8 Ga mafic-ultramafic Hamn intrusion, Northern Norway, with an aim to improve our ...
    • Volcanically hosted venting with indications of ultramafic influence at Aurora hydrothermal field on Gakkel Ridge 

      German, Christopher R.; Reeves, Eoghan; Türke, Andreas; Diehl, Alexander; Albers, Elmar; Bach, Wolfgang; Purser, Autun; Ramalho, Sofia P.; Suman, Stefano; Mertens, Christian; Walter, Maren; Ramirez-Llodra, Eva; Schlindwein, Vera; Bünz, Stefan; Boetius, Antje (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-31)
      The Aurora hydrothermal system, Arctic Ocean, hosts active submarine venting within an extensive field of relict mineral deposits. Here we show the site is associated with a neovolcanic mound located within the Gakkel Ridge rift-valley floor, but deep-tow camera and sidescan surveys reveal the site to be ≥100 m across—unusually large for a volcanically hosted vent on a slow-spreading ridge and more ...
    • Northeast Greenland (79.4 °N): Ice-free shelf edge around the Last Glacial Maximum 25.5-17.5 ka 

      Rasmussen, Tine Lander; Pearce, Christof; Andresen, Katrine Juul; Nielsen, Tove; Seidenkrantz, Marit Solveig (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-16)
      The size of the last glacial ice sheet on the Northeast (NE) Greenland shelf and its interaction with ocean circulation have been the subject of debate. Here we provide insights into the extent of the ice sheet around the Last Glacial Maximum (LGM) and investigate timing and strength of changes in the flow of Atlantic Water. The study is based on a multiproxy investigation of a marine sediment core, ...
    • Biogeochemistry and timing of methane-derived carbonate formation at Leirdjupet fault complex, SW Barents sea 

      Argentino, Claudio; Lee, Amicia; Fallati, Luca; Sahy, Diana; Birgel, Daniel; Peckmann, Jörn; Bünz, Stefan; Panieri, Giuliana (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-25)
      The origin of modern seafloor methane emissions in the Barents Sea is tightly connected to the glacio-tectonic and oceanographic transformations following the last ice age. Those regional events induced geological structure re-activation and destabilization of gas hydrate reservoirs over large areas of the European continental margins, sustaining widespread fluid plumbing systems. Despite the ...
    • An annual profile of the impacts of simulated oil spills on the Northeast Arctic cod and haddock fisheries 

      Carroll, JoLynn; Frøysa, Håvard Guldbrandsen; Vikebø, Frode Bendiksen; Broch, Ole Jacob; Howell, Daniel; Nepstad, Raymond; Augustine, Starrlight; Skeie, Geir Morten; Bockwoldt, Mathias (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-10)
      We simulate the combined natural and pollutant-induced survival of early life stages of NEA cod and haddock, and the impact on the adult populations in response to the time of a major oil spill in a single year. Our simulations reveal how dynamic ocean processes, controlling both oil transport and fate and the frequency of interactions of oil with drifting fish eggs and larvae, mediate the magnitude ...
    • Millennial-scale oscillations and an environmental regime shift around the Middle to Late Holocene transition in the North Atlantic region based on a multiproxy record from Isfjorden, West Spitsbergen 

      Brice, Camile; de Vernal, Anne; Francus, Pierre; Forwick, Matthias; Nam, Seung-II (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-04)
      Palynological and sedimentological analyses were performed on the sediment core HH16-1205-GC retrieved from the central Isfjorden, West Spitsbergen. The sequence, which spans the last 7000 years, revealed an overall cooling trend with an important climate shift between 4.4 and 3.8 cal. ka BP, in addition to millennial-scale oscillations. Sea-surface reconstruction from dinocyst assemblages indicates ...
    • TitaniQ temperatures and textural analysis as a record of the deformation history in a major continental shear zone system, Borborema Province, Brazil 

      Cavalcante, Carolina; de Jesus Costa, Juliana; Lagoeiro, Leonardo; Fossen, Haakon; Lee, Amicia; Archanjo, Carlos; Vizeu, Roberto (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-01)
      We combine quartz textural analysis with Titanium-in-quartz (TitaniQ) geothermometry to investigate the late stages of deformation in mylonitic rocks from the Sucuru dike swarm in the Borborema Province. The wide range in TitaniQ temperatures (>340 to 740 °C) closely related to grain sizes are attributed to inefficient Ti resetting during bulging (BLG) and subgrain rotation (SGR) recrystallization. ...
    • Paleoceanography of the Northwestern Greenland Sea and Return Atlantic Current evolution, 35–4 kyr BP 

      Devendra, Dhanushka; Łącka, Magdalena; Telesiński, Maciej M.; Rasmussen, Tine Lander; Sztybor, Kamila; Zajączkowski, Marek (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-10)
      The flow of the Atlantic Water (AW) via the Return Atlantic Current (RAC) regulates the oceanographical conditions in the Northwestern (NW) Greenland Sea in the Fram Strait. As the intensity of the RAC might significantly influence both deep-water formation in the area and the stability of the Northeast Greenland Ice Sheet (NE GIS), knowledge of its variability in the past is important. Here we ...
    • The Plastic Pathfinder: A macroplastic transport and fate model for terrestrial environments 

      Mellink, Yvette; Van Emmerik, Tim; Kooi, Merel; Laufkötter, Charlotte; Niemann, Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-24)
      Land-based plastic waste is the major source for freshwater and marine plastic pollution. Yet, the transport pathways over land remain highly uncertain. Here, we introduce a new conceptual model to forecast plastic transport on land: the Plastic Pathfinder; a numerical model that simulates the spatiotemporal distribution of macroplastic (>0.5 cm) at a river basin scale. The plastic transport driving ...
    • Nitrogen Isotope Evidence for Changing Arctic Ocean Ventilation Regimes During the Cenozoic 

      Knies, Jochen Manfred (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-03)
      In this work, I report on the coupling of dinitrogen (N<sub>2</sub>) fixation and denitrification in oxygen-deficient waters of the Arctic Ocean during the Paleogene. This coupling fertilized marine phytoplankton growth and favored organic carbon burial. Reduced vertical mixing due to salinity stratification in a tectonically closed oceanic basin created conditions favorable for N<sub>2</sub>-fixation ...