Now showing items 201-220 of 1046

    • 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 ...
    • Response of benthic foraminifera to environmental successions of cold seeps from Vestnesa Ridge, Svalbard: Implications for interpretations of paleo-seepage environments 

      Melaniuk, Katarzyna; Sztybor, Kamila; Treude, Tina; Sommer, Stefan; Zajaczkowski, Marek; Rasmussen, Tine Lander (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-15)
      This paper presents the results of a study on the response of living benthic foraminifera to progressing environmental successions in a cold-seep ecosystem. Sediment samples were collected from Vestnesa Ridge (79°N, Fram Strait) at ~1200 m water depth. The distribution of live (Rose Bengal-stained) foraminifera were analyzed in the upper sediment layers in relation to pore water biogeochemical data ...
    • Wood Jams Or Beaver Dams? Pliocene Life, Sediment And Landscape Interactions In The Canadian High Arctic 

      Davies, Neil S.; Gosse, John C; Rouillard, Alexandra; Rybczynski, Natalia; Meng, Jing; Reyes, Alberto V.; Kiguktak, Jarloo (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-28)
      During the mid-Pliocene (Zanclean, ca. ~ 3.9 Ma), parts of the Canadian High Arctic experienced mean annual temperatures that were 14–228C warmer than today and supported diverse boreal-type forests. The landscapes of this vegetated polar region left behind a fragmented sedimentary record that crops out across several islands in the Canadian Arctic Archipelago as the Beaufort Formation and correlative ...
    • A standard protocol for describing the evaluation of ecological models 

      Planque, Benjamin; Aarflot, Johanna Myrseth; Buttay, Lucie; Carroll, JoLynn; Fransner, Sara Filippa Krusmynta; Hansen, Cecilie; Husson, Berengere; Langangen, Øystein Ole Gahr; Lindstrøm, Ulf Ove; Pedersen, Torstein; Primicerio, Raul; Sivel, Elliot Manuarii; Skogen, Morten D.; Strombom, Evelyn; Stige, Leif Christian; Varpe, Øystein; Yoccoz, Nigel (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-21)
      Numerical models of ecological systems are increasingly used to address complex environmental and resource management questions. One challenge for scientists, managers, and stakeholders is to appraise how well suited these models are to answer questions of scientific or societal relevance, that is, to perform, communicate, or access transparent evaluations of ecological models. While there have been ...
    • Reconstruction of the Virtual Geomagnetic Pole (VGP) path at high latitude for the last 22 kyr: The role of radial field flux patches as VGP attractor 

      Caricchi, Chiara; Campuzano, Saioa A.; Sagnotti, Leonardo; Macri, Patrizia; Lucchi, Renata Giulia (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-24)
      Reconstruction of geomagnetic field changes has a strong potential to complement geodynamo modeling and improve the understanding of Earth's core dynamics. Recent works based on geomagnetic measurements pointed out that over the last two decades the position of the north magnetic pole has been largely determined by the influence of two competing flux lobes under Canada and Siberia. In order to ...
    • Variability in transport of terrigenous material on the shelves and the deep Arctic Ocean during the Holocene 

      Wegner, C.; Bennet, K.; Vernal, Anne de; Forwick, Matthias; Fritz, M.; Heikkilä, Maija; Łącka, Magdalena; Lantuit, Hugues; Laska, Michał; Moskalik, Mateusz; O’Regan, Matt; Pawłowska, J; Promińska, Agnieszka; Rachold, Volker; Vonk, Jorien E.; Werner, Kirstin (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-09)
      Arctic coastal zones serve as a sensitive filter for terrigenous matter input onto the shelves via river discharge and coastal erosion. This material is further distributed across the Arctic by ocean currents and sea ice. The coastal regions are particularly vulnerable to changes related to recent climate change. We compiled a pan-Arctic review that looks into the changing Holocene sources, transport ...
    • Locally Resolved Stress-State in Samples During Experimental Deformation: Insights Into the Effect of Stress on Mineral Reactions 

      Cionoiu, S.; Moulas, E.; Stunitz, Holger; Tajcmanova, L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-17)
      Understanding conditions in the Earth's interior requires data derived from laboratory experiments. Such experiments provide important insights into the conditions under which mineral reactions take place as well as processes that control the localization of deformation in the deep Earth. We performed Griggs-type general shear experiments in combination with numerical models, based on continuum ...
    • Iron isotopes constrain sub-seafloor hydrothermal processes at the Trans-Atlantic Geotraverse (TAG) active sulfide mound 

      Sahlström, Fredrik; Troll, Valentin R; Strmic Palinkas, Sabina; Kooijman, Ellen; Zheng, Xinyuan (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-29)
      Sub-seafloor hydrothermal processes along volcanically active plate boundaries are integral to the formation of seafloor massive sulfide deposits and to oceanic iron cycling, yet the nature of their relationship is poorly understood. Here we apply iron isotope analysis to sulfide minerals from the Trans-Atlantic Geotraverse (TAG) mound and underlying stockwork, 26°N Mid-Atlantic Ridge, to trace ...
    • Thermal state of the Guaymas Basin derived from gas hydrate bottom simulating reflections and heat flow measurements 

      Sarkar, Sudipta; Moser, Manuel; Berndt, Christian; Doll, Mechthild; Böttner, Christoph; Chi, Wu-Cheng; Klaeschen, Dirk; Galerne, Christophe; Karstens, Jens; Geilert, Sonja; Mortera-Gutierrez, C.; Hensen, Christian (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-20)
      Seafloor heat flow provides information about the thermal evolution of the lithosphere, the magnitude and timing of volcanic activity, and hydrothermal circulation patterns. In the central Gulf of California, the Guaymas Basin is part of a young marginal spreading rift system that experiences high sedimentation (1–5 km/Myr) and widespread magmatic intrusions in the axial troughs and the off-axis ...
    • Greenland ice sheet climate disequilibrium and committed sea-level rise 

      Box, Jason E.; Hubbard, Alun Lloyd; Bahr, David B.; Colgan, William T.; Fettweis, Xavier; Mankoff, Kenneth D.; Wehrlé, Adrien; Noel, Brice; Van Den Broeke, Michiel R.; Wouters, Bert; Bjørk, Anders A.; Fausto, Robert S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-29)
      Ice loss from the Greenland ice sheet is one of the largest sources of contemporary sea-level rise (SLR). While process-based models place timescales on Greenland’s deglaciation, their confidence is obscured by model shortcomings including imprecise atmospheric and oceanic couplings. Here, we present a complementary approach resolving ice sheet disequilibrium with climate constrained by satellite-derived ...