Viser treff 464-483 av 711

    • Palaeoceanographic and environmental changes in the eastern Fram Strait during the last 14,000 years based on benthic and planktonic foraminifera 

      Consolaro, Chiara; Rasmussen, Tine Lander; Panieri, Giuliana (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-14)
      Benthic and planktonic foraminifera, stable isotopes and other geochemical and sedimentological parameters have been investigated in a sediment core from Vestnesa Ridge (79°N, NW Svalbard margin, 1300 m water depth) in order to reconstruct the palaeoceanographic and palaeoenvironmental evolution of the eastern Fram Strait during the last 14,000 years. Our multiproxy data and, in particular, our ...
    • Palaeoceanographic reconstruction of surface-ocean changes in the southern Norwegian Sea for the last ~130,000 years based on diatoms and with comparison to foraminiferal records 

      Hoff, Ulrike; Rasmussen, Tine Lander; Meyer, Hanno; Koc, Nalan; Hansen, Jesper (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-28)
      Fossil marine diatom assemblages in a sediment core from the central northern Faroe slope in the Norwegian Sea were used to reconstruct palaeoceanographic changes in the surface water mixed layer from the last ~130,000 years (Marine Isotope Stage (MIS) 6/5 transition to MIS 1 (including the Eemian and Holocene interglacials) and to compare the results with previously published results on planktic ...
    • Palaeoceanography of the Barents Sea continental margin, north of Nordaustlandet, Svalbard, during the last 74 ka 

      Chauhan, Teena; Rasmussen, Tine Lander; Noormets, Riko (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-17)
      We investigated gravity core HH11‐09GC from 488 m water depth at the northern Svalbard margin in order to reconstruct changes in Atlantic Water (AW) inflow to the Arctic Ocean. The study was based on the distribution patterns of benthic and planktic foraminifera, benthic and planktic oxygen and carbon isotopes, lithology and physical properties of the sediments. The core contains sediments from ...
    • Palaeoproterozoic foreland fold-thrust belt structures and lateral faults in the West Troms Basement Complex, northern Norway, and their relation to inverted metasedimentary sequences 

      Paulsen, Hanne-Kristin; Bergh, Steffen G; Palinkas, Sabina Strmic; Karlsen, Siri; Kolsum, Sofie; Rønningen, Ida Ulvik; Armitage, Paul E.B.; Nasuti, Aziz (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-15)
      Palaeoproterozoic fold-thrust belt structures and steep, lateral shear zones characterize the foreland deformation of Neoarchaean basement tonalites in Vanna, West Troms Basement Complex, northern Norway. Low-grade par-autochthonous and allochthonous cover units (2.4–2.2. Ga) with sandstones and calcareous metapelites exist in separate areas of the foreland. They were formed as intracontinental rift- ...
    • The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System 

      Orvik, Alf Andre; Slagstad, Trond; Hansen, Harald; Nilsson, Lars Petter; Sørensen, Bjørn Eske (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-14)
      The modern concepts of magmatic plumbing systems have evolved from simple models of melt-dominated crustal magma chambers to magmatic systems that span the continental crust. The geochemistry of these systems is challenging to model numerically because of a complex polybaric and multiphase evolution, which is not well described by mathematic end-member formulas. We propose that a recent modelling ...
    • Palaeoproterozoic oxygenated oceans following the Lomagundi–Jatuli Event 

      Mänd, Kaarel; Lalonde, Stefan V.; Robbins, Leslie J.; Thoby, Marie; Paiste, Kärt; Kreitsmann, Timmu; Paiste, Päärn; Reinhard, Christopher T.; Romashkin, Alexandr E.; Planavsky, Noah J.; Kirsimäe, Kalle; Lepland, Aivo; Konhauser, Kurt O. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-16)
      The approximately 2,220–2,060 million years old Lomagundi–Jatuli Event was the longest positive carbon isotope excursion in Earth history and is traditionally interpreted to reflect an increased organic carbon burial and a transient rise in atmospheric O<sub>2</sub>. However, it is widely held that O<sub>2</sub> levels collapsed for more than a billion years after this. Here we show that black shales ...
    • Paleo-methane emissions recorded in foraminifera near the landward limit of the gas hydrate stability zone offshore western Svalbard 

      Panieri, Giuliana; Graves, Carolyn; James, Rachel (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-26)
      We present stable isotope and geochemical data from four sediment cores from west of Prins Karls Forland (ca. 340 m water depth), offshore western Svalbard, recovered from close to sites of active methane seepage, as well as from shallower water depths where methane seepage is not presently observed. Our analyses provide insight into the record of methane seepage in an area where ongoing ocean ...
    • The Paleoarchean Buffalo River komatiites: Progressive melting of a single large mantle plume beneath the growing Kaapvaal craton 

      Netshidzivhe, Thendo; Tappe, Sebastian; Wilson, Allan H.; Ishikawa, Akira; Viljoen, Fanus (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-01)
      Several Archean granitoid-greenstone terranes are exposed on the southeastern Kaapvaal craton in South Africa, but they received little scientific attention compared to the archetypal greenstone belt successions of the Barberton Mountain Land at the eastern craton margin. This study reports on a detailed field and geochemical survey of the Buffalo River Greenstone Belt at the southern Kaapvaal craton ...
    • Paleobathymetric reconstructions of the SW Barents Seaway and their implications for Atlantic–Arctic ocean circulation 

      Lasabuda, Amando P. E.; Hanssen, Alfred; Laberg, Jan Sverre; Faleide, Jan Inge; Patton, Henry; Abdelmalak, Mohamed Mansour; Rydningen, Tom Arne; Kjølhamar, Bent (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-29)
      Unravelling past, large-scale ocean circulation patterns is crucial for deciphering the longterm global paleoclimate. Here we apply numerical modelling to reconstruct the detailed paleobathymetry-topography of the southwestern inlet of the Barents Seaway that presently connects the Atlantic and Arctic oceans. Subaerial topography was likely enough to block Atlantic Water from entering the Barents ...
    • Paleoceanographic development in Storfjorden, Svalbard, during the deglaciation and Holocene: evidence from benthic foraminiferal records 

      Rasmussen, Tine Lander; Thomsen, Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-08-07)
      Brines can have a profound influence on the relative abundance of calcareous and agglutinated foraminiferal faunas. Here we investigated the distribution of benthic foraminiferal species in four cores from a brine‐enriched environment in Storfjorden, Svalbard. Stratigraphically, the cores comprise the last 15 000 years. The purpose of the study was to reconstruct changes in the palaeoecology and ...
    • 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 ...
    • Particle sources and downward fluxes in the eastern Fram strait under the influence of the west Spitsbergen current 

      Sanchez-Vidal, Anna; Veres, Oriol; Langone, Leonardo; Ferré, Benedicte; Calafat, Antoni; Canals, Miquel; Durrieu de Madron, Xavier; Heussner, Serge; Mienert, Jurgen; Grimalt, Joan O.; Pusceddu, Antonio; Danovaro, Roberto (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-06-10)
      <p>The carbon cycle of the Arctic Ocean is tightly regulated by land–atmosphere–cryosphere–ocean interactions. Characterizing these environmental exchanges and feedbacks is critical to facilitate projections of the carbon cycle under changing climate conditions. The environmental drivers of sinking particles including organic carbon (OC) to the deep-sea floor are investigated with four moorings ...
    • Passive seismic recording of cryoseisms in Adventdalen, Svalbard 

      Romeyn, Rowan; Hanssen, Alfred; Ruud, Bent Ole; Stemland, Helene Meling; Johansen, Tor Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-20)
      A series of transient seismic events were discovered in passive seismic recordings from 2-D geophone arrays deployed at a frost polygon site in Adventdalen, Svalbard. These events contain a high proportion of surface wave energy and produce high-quality dispersion images using an apparent offset re-sorting and inter-trace delay minimisation technique to locate the seismic source, followed by ...
    • Past ice sheet-seabed interactions in the northeastern Weddell Sea embayment, Antarctica 

      Arndt, Jan Erik; Larter, Robert D.; Hillenbrand, Claus-Dieter; Sørli, Simon H.; Forwick, Matthias; Smith, James A.; Wacker, Lukas (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-30)
      The Antarctic ice sheet extent in the Weddell Sea embayment (WSE) during the Last Glacial Maximum (LGM; ca. 19–25 calibrated kiloyears before present, ka cal BP) and its subsequent retreat from the shelf are poorly constrained, with two conflicting scenarios being discussed. Today, the modern Brunt Ice Shelf, the last remaining ice shelf in the northeastern WSE, is only pinned at a single location ...
    • Pelagic calcium carbonate production and shallow dissolution in the North Pacific Ocean 

      Ziveri, Patrizia; Gray, William Robert; Anglada Ortiz, Griselda; Manno, Clara; Grelaud, Michael; Incarbona, Alessandro; Rae, James William Buchanan; Subhas, Adam V.; Pallacks, Sven; White, Angelicque; Adkins, Jess F.; Berelson, William (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-20)
      Planktonic calcifying organisms play a key role in regulating ocean carbonate chemistry and atmospheric CO<sub>2</sub>. Surprisingly, references to the absolute and relative contribution of these organisms to calcium carbonate production are lacking. Here we report quantification of pelagic calcium carbonate production in the North Pacific, providing new insights on the contribution of the three ...
    • Permafrost in monitored unstable rock slopes in Norway-New insights from temperature and surface velocity measurements, geophysical surveying, and ground temperature modelling 

      Etzelmüller, Bernd; Czekirda, Justyna; Magnin, Florence; Duvillard, Pierre-Allain; Ravanel, Ludovic; Malet, Emanuelle; Aspaas, Andreas Grøvan; Kristensen, Lene; Skrede, Ingrid; Majala, Gudrun D.; Jacobs, Benjamin; Leinauer, Johannes; Hauck, Christian; Hilbich, Christin; Böhme, Martina; Hermanns, Reginald; Eriksen, Harald Øverli; Lauknes, Tom Rune; Krautblatter, Michael; Westermann, Sebastian (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-01)
      The warming and subsequent degradation of mountain permafrost within alpine areas represent an important process influencing the stability of steep slopes and rock faces. The unstable and monitored slopes of Mannen (Møre and Romsdal county, southern Norway) and Gámanjunni-3 (Troms and Finnmark county, northern Norway) were classified as high-risk sites by the Norwegian Geological Survey (NGU). ...
    • The Permafrost Young Researchers Network (PYRN) is getting older – the past, present, and future of our evolving community 

      Tanski, George; Bergstedt, Helena; Bevington, Alexandre; Bonnaventure, Philip; Bouchard, Frédéric; Coch, Caroline; Dumais, Simon; Evgrafova, Alvetina; Frauenfeld, Oliver; Frederick, Jennifer; Fritz, Michael; Frolov, Denis; Harder, Silvie; Hartmeyer, Ingo; Heslop, Joanne; Högström, Elin; Johansson, Margareta; Kraev, Gleb; Kuznetsova, Elena; Lenz, Josefine; Lupachev, Alexey; Magnin, Florence; Martens, Jannik; Maslakov, Alexey; Morgenstern, Anne; Nieuwendam, Alexandre; Oliva, Marc; Radosavljevic, Boris; Ramage, Justine; Schneider, Andrea; Stanilovskaya, Julia; Strauss, Jens; Trochim, Erin; Vecellio, Daniel; Weber, Samuel; Lantuit, Hugues (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-07)
      A lasting legacy of the International Polar Year (IPY) 2007–2008 was the promotion of the Permafrost Young Researchers Network (PYRN), initially an IPY outreach and education activity by the International Permafrost Association (IPA). With the momentum of IPY, PYRN developed into a thriving network that still connects young permafrost scientists, engineers, and researchers from other disciplines. ...
    • Persistence of Holocene ice cap in northeast Svalbard aided by glacio-isostatic rebound 

      Farnsworth, Wesley Randall; Ingólfsson, Ólafur; Brynjólfsson, Skafti; Allaart, Lis; Kjellman, Sofia Elisabeth; Kjær, Kurt H.; Larsen, Nicolaj K.; Macias-Fauria, Marc; Siggaard-Andersen, Marie-Louise; Schomacker, Anders (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-29)
      The deglaciation of the Svalbard-Barents Sea Ice Sheet was driven by relative sea-level rise, the incursion of North Atlantic waters around Spitsbergen, and increasing summer insolation. However, ice retreat was inter rupted by asynchronous re-advances that occurred into high relative seas, during a period associated with warm regional waters and elevated summer temperatures. Better understanding ...
    • Petrogenesis and Geodynamic Significance of Xenolithic Eclogites 

      Aulbach, Sonja; Smart, Katie (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-15)
      Kimberlite-borne xenolithic eclogites, typically occurring in or near cratons, have long been recognized as remnants of Precambrian subducted oceanic crust that have undergone partial melting to yield granitoids similar to the Archaean continental crust. While some eclogitized oceanic crust was emplaced into cratonic lithospheres, the majority was deeply subducted to form lithologic and geochemical ...
    • 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 ...