Viser treff 241-260 av 1011

    • Hammerfest Basin Composite Tectono-Sedimentary Element 

      Henriksen, Erik; Kvamme, L.; Rydningen, Tom Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-21)
      The Hammerfest Basin is an E -W trending graben located between the Loppa High and the Finnmark Platform in the southern part of the Norwegian Barents Sea. Mainly siliciclastic strata of Carboniferous to Cenozoic age cover the Caledonian basement and have a total estimated thickness of 5-8 km. The basin evolved through several tectonic phases: the Carboniferous rifting, Late Jurassic rifting, the ...
    • Living and dead foraminiferal assemblages of the last decades from Kveithola Trough: Taphonomic processes and ecological highlights 

      Gamboa-Sojo, Viviana Maria; Husum, Katrine; Caridi, Francesca; Lucchi, Renata Giulia; Bensi, Manuel; Kovačević, Vedrana; Sabbatini, Anna; Langone, Leonardo; Dominiczak, Aleksander Tadeusz; Povea, Patricia; Morigi, Caterina (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-15)
      We examine the living and dead benthic foraminiferal assemblages from the topmost 10 cm (using 150 μm sieve fraction) of three sedimentological short records collected in the Kveithola Trough (northwest Barents Sea). Our aim is to reconstruct the environmental variations of the last decades, connected to the interaction among the North Atlantic and the Arctic water masses. Our samples are collected ...
    • High resolution inclination records from the Gulf of Alaska, IODP Expedition 341 Sites U1418 and U1419 

      Velle, Julie Heggdal; Walczak, Maureen H.; Reilly, Brendan T; St-Onge, Guillaume; Stoner, Joseph S.; Fallon, Stewart J.; Mix, Alan C.; Belanger, Christina L.; Forwick, Matthias (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-26)
      International Ocean Drilling Program (IODP) Expedition 341 recovered sediments from the south Alaska continental slope that preserves a well resolved and dated inclination record over most of the past ∼43 000 yr. The Site U1419 chronology is among the highest resolution in the world, constrained by 173 radiocarbon dates, providing the ability to study Palaeomagnetic Secular Variation (PSV) on ...
    • 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 ...
    • Influence of methane seepage on isotopic signatures in living deep-sea benthic foraminifera, 79° N 

      Melaniuk, Katarzyna; Sztybor, Kamila; Treude, Tina; Sommer, Stefan; Rasmussen, Tine Lander (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-21)
      Fossil benthic foraminifera are used to trace past methane release linked to climate change. However, it is still debated whether isotopic signatures of living foraminifera from methane-charged sediments refect incorporation of methane-derived carbon. A deeper understanding of isotopic signatures of living benthic foraminifera from methane-rich environments will help to improve reconstructions of ...
    • Variability of Marine Methane Bubble Emissions on the Clayoquot Slope, Offshore Vancouver Island, Between 2017 and 2021 

      Marcon, Yann; Römer, Miriam; Scherwath, Martin; Riedel, Michael; Dølven, Knut Ola; Heesemann, Martin (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-17)
      Seabed methane gas emissions occur worldwide at cold seeps located along most continental margins. Fluxes of methane gas released from the seabed in the form of bubbles can be extremely variable even over short time intervals. Some factors controlling the variability are still poorly understood. Here, we report on the results of continuous long-term sonar monitoring of bubble emissions at a depth ...
    • Dissolution precipitation creep as a process for the strain localisation in mafic rocks 

      Lee, Amicia; Stunitz, Holger; Soret, Mathieu; Battisti, Matheus Ariel (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-01)
      The lower crust is, on average, mafic in composition and composed of minerals that remain mechanically strong up to high temperatures. Here we show that dissolution-precipitation creep (as a type of diffusion creep) plays a major role in deformation of gabbro bodies at upper amphibolite facies conditions. The Kågen gabbro, N. Norway, is comprised of undeformed gabbro lenses enclosed by mylonitised ...
    • A large West Antarctic Ice Sheet explains early Neogene sea-level amplitude 

      Marschalek, J. W.; Zurli, L.; Talarico, F.; van de Flierdt, T.; Vermeesch, P.; Carter, A.; Beny, F.; Bout-Roumazeilles, V.; Sangiorgi, F.; Hemming, S. R.; Pérez, L. F.; Colleoni, F.; Prebble, J. G.; van Peer, T. E.; Perotti, M.; Shevenell, A. E.; Browne, I.; Kulhanek, D. K.; Levy, R.; Harwood, D.; Sullivan, N. B.; Meyers, S. R.; Griffith, E. M.; Hillenbrand, C. D.; Gasson, E.; Siegert, M. J.; Keisling, B.; Licht, K. J.; Kuhn, G.; Dodd, J. P.; Boshuis, C.; de Santis, L.; McKay, R. M.; Ash, J.; Cortese, G.; Esper, O. V.; Gales, J. A.; Ishino, S.; Kim, Sookwan; Kim, Sunghan; Laberg, Jan Sverre; Leckie, R. M.; Muller, J.; Patterson, M. O.; Romans, B. W.; Romero, O. E.; Seki, O.; Singh, S. M.; Cordeiro de Sousa, I. M.; Sugisaki, S. T. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021)
      Early to Middle Miocene sea-level oscillations of approximately 40–60 m estimated from far-field records1,2,3 are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth2. This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene4,5. Data and model outputs can ...
    • Temporal Variability of Surface Reflectance Supersedes Spatial Resolution in Defining Greenland’s Bare-Ice Albedo 

      Irvine-Fynn, Tristram D. L.; Bunting, Peter S.; Cook, Joseph M.; Hubbard, Alun; Barrand, Nicholas E.; Hanna, Edward; Hardy, Andy J.; Hodson, Andrew J.; Holt, Tom O.; Huss, Matthias; McQuaid, James B.; Nilsson, Johan; Naegeli, Kathrin; Roberts, Osian; Ryan, Jonathan C.; Tedstone, Andrew J.; Tranter, Martyn; Williamson, Christopher J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-23)
      Ice surface albedo is a primary modulator of melt and runoff, yet our understanding of how reflectance varies over time across the Greenland Ice Sheet remains poor. This is due to a disconnect between point or transect scale albedo sampling and the coarser spatial, spectral and/or temporal resolutions of available satellite products. Here, we present time-series of bare-ice surface reflectance data ...
    • Impact of Timanian thrust systems on the late Neoproterozoic–Phanerozoic tectonic evolution of the Barents Sea and Svalbard 

      Koehl, Jean-Baptiste Philippe; Magee, Craig; Anell, Ingrid (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-12)
      The Svalbard Archipelago consists of three basement terranes that record a complex Neoproterozoic– Phanerozoic tectonic history, including four contractional events (Grenvillian, Caledonian, Ellesmerian, and Eurekan) and two episodes of collapse- to rift-related extension (Devonian–Carboniferous and late Cenozoic). Previous studies suggest that these three terranes likely accreted during the early ...
    • How Academics and the Public Experienced Immersive Virtual Reality for Geo-Education 

      Bonali, Fabio L.; Russo, Elena; Vitello, Fabio; Antoniou, Varvara; Marchese, Fabio; Fallati, Luca; Bracchi, Valentina; Corti, Noemi; Savini, Alessandra; Whitworth, Malcom; Drymoni, Kyriaki; Mariotto, Federico Pasquaré; Nomikou, Paraskevi V.; Sciacca, Eva; Bressan, Sofia; Falsaperla, Susanna; Reitano, Danilo; van Wyk de Vries, Benjamin; Krokos, Mel; Panieri, Giuliana; Stiller-Reeve, Matthew Alexander; Vizzari, Giuseppe; Becciani, Ugo; Tibaldi, Alessandro (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-24)
      Immersive virtual reality can potentially open up interesting geological sites to students, academics and others who may not have had the opportunity to visit such sites previously. We study how users perceive the usefulness of an immersive virtual reality approach applied to Earth Sciences teaching and communication. During nine immersive virtual reality-based events held in 2018 and 2019 in ...
    • Mineral paragenesis and sulphide trace element distribution in the metamorphosed Lovisa Zn-Pb deposit, Bergslagen (Sweden), as revealed by 3D X-ray tomography, ore petrography and LA-ICP-MS analysis 

      Andersson, Stefan S.; Sahlström, Fredrik; Jonsson, Erik; Luth, Stefan; Lynch, Edward P.; Högdahl, Karin; Zack, Thomas; Gies, Nils; Sädbom, Stefan; Alexander Hansson, K.S.; Bergqvist, Mikael (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-29)
      This study encompasses the ore mineralogy, textures and sulphide trace element chemistry of the Palaeoproterozoic Lovisa stratiform Zn-Pb deposit and the stratigraphically underlying Lovisa Fe Formation in the Bergslagen ore province (Sweden). We investigate the relative timing of formation and subsequent modifications of its ores in relation to the c. 1.87–1.80 Ga Svecokarelian orogeny. The Lovisa ...
    • Physical weathering by glaciers enhances silicon mobilisation and isotopic fractionation 

      Hatton, J.E.; Hendry, K.R.; Hawkings, J.R.; Wadham, Jemma Louise; Benning, L.G.; Blukis, R.; Roddatis, V.; Ng, H.C.; Wang, T. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-06)
      Glacial meltwaters export substantial quantities of dissolved and dissolvable amorphous silicon (DSi and ASi), providing an essential nutrient for downstream diatoms. Evidence suggests that glacially exported DSi is isotopically light compared to DSi in non-glaciated rivers. However, the isotopic fractionation mechanisms are not well constrained, indicating an important gap in our understanding ...
    • Origin and Periodic Behavior of Short Duration Signals Recorded by Seismometers at Vestnesa Ridge, an Active Seepage Site on the West-Svalbard Continental Margin 

      Domel, Przemyslaw; Singhroha, Sunny; Plaza-Faverola, Andreia; Schlindwein, Vera; Ramachandran, Hariharan; Bünz, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-02)
      Short duration events (SDEs) are reported worldwide from ocean-bottom seismometers (OBSs). Due to their high frequency (4–30 Hz) and short duration, they are commonly attributed to aseismic sources, such as fluid migration related processes from cold seeps, biological signals, or noise. We present the results of a passive seismic experiment that deployed an OBS network for 10-month (October 2015–July ...
    • Glacier response to the Little Ice Age during the Neoglacial cooling in Greenland 

      Kjær, Kurt H.; Bjørk, Anders A.; Kjeldsen, Kristian K.; Hansen, Eric S.; Andresen, Camilla S.; Siggaard-Andersen, Marie-Louise; Khan, Shfaqat Abbas; Søndergaard, Anne Sofie; Colgan, William; Schomacker, Anders; Woodroffe, Sarah; Funder, Svend; Rouillard, Alexandra; Jensen, Jens Fog; Larsen, Nicolaj K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-04)
      In the Northern Hemisphere, an insolation driven Early to Middle Holocene Thermal Maximum was followed by a Neoglacial cooling that culminated during the Little Ice Age (LIA). Here, we review the glacier response to this Neoglacial cooling in Greenland. Changes in the ice margins of outlet glaciers from the Greenland Ice Sheet as well as local glaciers and ice caps are synthesized Greenland-wide. ...
    • Development of the NORSAR Network over the Last 50 Yr 

      Schweitzer, Johannes; Köhler, Andreas; Christensen, Jon Magnus (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-27)
      This contribution describes the development of Norwegian Seismic Array (NORSAR), from its origin 50 yr ago as a project for installing a single seismic array in southern Norway to a seismological research institute operating a network of six arrays and 14 three‐component stations located in Norway and Antarctica. In addition, we document the different instrumentations from narrowband, mostly ...
    • Seismic and electrical geophysical characterization of an incipient coastal open-system pingo: Lagoon Pingo, Svalbard 

      Hammock, Craig Paul; Kulessa, Bernd; Hiemstra, John F.; Hodson, Andrew; Hubbard, Alun (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-24)
      Whilst there has been a recent appreciation for the role of open-system pingos in providing a fluid-flow conduit through continuous permafrost that enables methane release, the formation and internal structure of these ubiquitous permafrost-diagnostic landforms remains unclear. Here, we combine active-source seismic measurements with electrical resistivity tomography (ERT) to investigate the structural ...
    • Autonomous methane seep site monitoring offshore western Svalbard: hourly to seasonal variability and associated oceanographic parameters 

      Dølven, Knut Ola; Ferré, Benedicte; Silyakova, Anna; Jansson, Pär; Linke, Peter; Moser, Manuel (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-18)
      Improved quantification techniques of natural sources are needed to explain variations in atmospheric methane. In polar regions, high uncertainties in current estimates of methane release from the seabed remain. We present unique 10- and 3-month time series of bottom water measurements of physical and chemical parameters from two autonomous ocean observatories deployed at separate intense seabed ...
    • Decadal trend of plankton community change and habitat shoaling in the Arctic gateway recorded by planktonic foraminifera 

      Greco, Mattia; Werner, Kristin; Zamelczyk, Katarzyna; Rasmussen, Tine Lander; Kucera, Michal (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-16)
      The Fram Strait plays a crucial role in regulating the heat and sea-ice dynamics in the Arctic. In response to the ongoing global warming, the marine biota of this Arctic gateway is experiencing significant changes with increasing advection of Atlantic species. The footprint of this ‘Atlantification’ has been identified in isolated observations across the plankton community, but a systematic, ...
    • A practical method to determine the five-parameter orientation of intragranular boundaries in polycrystals 

      Lloyd, Geoffrey E.; Lee, Amicia; Kahl, Maren (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-04)
      Intragranular boundaries are important features of polycrystalline materials and impact on many physical and chemical properties. Knowledge of their physical orientation is often crucial to explain such properties. However, it has proved difficult to determine the complete orientation of intragranular boundaries, which involves the misorientation angle and axis about which the adjacent crystal ...