Now showing items 288-307 of 315

    • Temperature observations from northernmost Greenland, 2006-2010 

      Schomacker, Anders; Larsen, Nicolaj K.; Bjørk, Anders A.; Kjær, Kurt H. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-31)
      Air-, surface-, and subsurface temperatures were recorded by automatic weather stations in Bliss Bugt and Moore Gletscher, Johannes V. Jensen Land, North coast of Greenland from 2006-2010. The mean annual surface temperature is -12.1 ℃ in Bliss Bugt and -13.8 ℃ at Moore Gletscher. In 20 cm depth below the surface at Moore Gletscher, the mean annual temperature is -13.2 ℃ (2007-2008). High-amplitude ...
    • Temporal and spatial structure of multi-millennial temperature changes at high latitudes during the Last Interglacial 

      Capron, Emilie; Govin, Aline; Stone, Emma J.; Masson-Delmotte, Valérie; Mulitza, Stefan; Otto-Bliesner, Bette; Rasmussen, Tine Lander; Sime, Louise C.; Waelbroeck, Claire; Wolff, Eric W. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Temporal constraints on hydrate-controlled methane seepage off Svalbard 

      Berndt, Christian; Feseker, Tomas; Treude, Tina; Krastel, Sebastien; Liebetrau, Volker; Niemann, Helge; Bertics, Victoria; Dumke, Ines; Dünnbier, Karolin; Ferré, Benedicte; Graves, Carolyn; Gross, Felix; Hissmann, Karen; Hühnerbach, Veit; Krause, Stefan; Lieser, Kathrin; Schauer, Jürgen; Steinle, Lea (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-01-17)
      Methane hydrate is an icelike substance that is stable at high pressure and low temperature in continental margin sediments. Since the discovery of a large number of gas flares at the landward termination of the gas hydrate stability zone off Svalbard, there has been concern that warming bottom waters have started to dissociate large amounts of gas hydrate and that the resulting methane release may ...
    • A Theoretical Model of Drumlin Formation Based on Observations at Múlajökull, Iceland 

      Iverson, N. R.; McCracken, R. G.; Zoet, L. K.; Benediktsson, Í. Ö.; Schomacker, Anders; Johnson, M. D.; Woodard, J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-20)
      The drumlin field at the surge‐type glacier, Múlajökull, provides an unusual opportunity to build a model of drumlin formation based on field observations in a modern drumlin‐forming environment. These observations indicate that surges deposit till layers that drape the glacier forefield, conform to drumlin surfaces, and are deposited in shear. Observations also indicate that erosion helps create ...
    • Thermogenic methane injection via bubble transport into the upper Arctic Ocean from the hydrate-charged Vestnesa Ridge, Svalbard 

      Smith, Andrew James; Mienert, Jurgen; Bünz, Stefan; Greinert, Jens (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-04-21)
      We use new gas‐hydrate geochemistry analyses, echosounder data, and three‐dimensional P‐Cable seismic data to study a gas‐hydrate and free‐gas system in 1200 m water depth at the Vestnesa Ridge offshore NW Svalbard. Geochemical measurements of gas from hydrates collected at the ridge revealed a thermogenic source. The presence of thermogenic gas and temperatures of ∼3.3°C result in a shallow top of ...
    • Tidal Energy Loss, Internal Tide Radiation, and Local Dissipation for Two-Layer Tidal Flow over a Sill 

      Arneborg, Lars; Jansson, Pær; Staalstrøm, Andre; Broström, Göran (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-14)
      A simple analytical model for tidal energy loss at fjord sills and its partitioning into local dissipation and radiated internal tides is presented. The analytical model builds on a two-layer assumption with quasi-steady nonlinear flow over the sill and wave radiation in the far field. When the interface is situated above sill level, upstream- and downstream-propagating internal waves are generated ...
    • Til IBGs 20-års-jubileum 

      Labugt, Sylvia (Preprint; Manuskript, 1992)
    • Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet 

      Cremiere, Antoine; Lepland, Aivo; Chand, Shyam; Sahy, Diana; Condon, Daniel J.; Noble, Stephen R.; Martma, Tõnu; Thorsnes, Terje; Sauer, Simone; Brunstad, Harald (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-11)
      Gas hydrates stored on continental shelves are susceptible to dissociation triggered by environmental changes. Knowledge of the timescales of gas hydrate dissociation and subsequent methane release are critical in understanding the impact of marine gas hydrates on the ocean–atmosphere system. Here we report a methane efflux chronology from five sites, at depths of 220–400 m, in the southwest Barents ...
    • Two-billion-year-old evaporites capture Earth’s great oxidation 

      Blättler, C.L.; Claire, M.W.; Prave, A.R.; Kirsimäe, K.; Higgins, J.A.; Medvedev, P.V.; Romashkin, A.E; Rychanchik, D.V.; Zerkle, A.L.; Paiste, Kärt; Kreitsmann, T.; Millar, I.L.; Hayles, J.A.; Bao, H.; Turchyn, A.V.; Warke, M.R.; Lepland, Aivo (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-20)
      Major changes in atmospheric and ocean chemistry occurred in the Paleoproterozoic era (2.5 to 1.6 billion years ago). Increasing oxidation dramatically changed Earth’s surface, but few quantitative constraints exist on this important transition. This study describes the sedimentology, mineralogy, and geochemistry of a 2-billion-year-old, ~800-meter-thick evaporite succession from the Onega Basin in ...
    • Two-stage exhumation of subducted Saxothuringian continental crust records underplating in the subduction channel and collisional forced folding (Krkonoše-Jizera Mts., Bohemian Massif) 

      Jerabek, Petr; Konopasek, Jiri; Žáčková, Eliška (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-08)
      The Krkonoše-Jizera Massif in the northern part of the Variscan Bohemian Massif provides insight into the exhumation mechanisms for subducted continental crust. The studied region exposes a relatively large portion of a flat-lying subduction-related complex that extends approximately 50 km away from the paleosuture. wide extent of HP-LT metamorphism has been confirmed by new P-T estimates indicating ...
    • U-Th chronology and formation controls of methane-derived authigenic carbonates from the Hola trough seep area, northern Norway 

      Sauer, Simone; Knies, Jochen; Lepland, Aivo; Sahy, Diana; Martma, Tõnu; Noble, Stephen R.; Schönenbergerb, Jasmin; Klug, Martin; Schubert, Carsten J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-20)
      We investigated methane-derived authigenic carbonate (MDAC) crusts and nodules from a cold seep site on the northern Norwegian continental shelf in ca. 220 m water depth to determine the timing and mode of their formation. Gas bubbling observed during remotely operated vehicle (ROV)-assisted sampling of MDAC crusts revealed ongoing seep activity. Authigenic carbonates were present as crusts on the ...
    • UAV photogrammetry and structure from motion to assess calving dynamics at Store Glacier, a large outlet draining the Greenland ice sheet 

      Ryan, Johnny C.; Hubbard, Alun Lloyd; Box, Jason E.; Todd, Joe; Christoffersen, Poul; Carr, J. Rachel; Holt, Tom O.; Snooke, Neal A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-06)
      This study presents the application of a costeffective, unmanned aerial vehicle (UAV) to investigate calving dynamics at a major marine-terminating outlet glacier draining the western sector of the Greenland ice sheet. The UAV was flown over Store Glacier on three sorties during summer 2013 and acquired over 2000 overlapping, geotagged images of the calving front at an ∼ 40 cm ground sampling ...
    • Undersjøiske daler og oljereservoar 

      Vorren, Tore Ola; Laberg, Jan Sverre (Chronicle; Kronikk, 2010-10-02)
    • Undersjøiske kjempeskred og flodbølger 

      Vorren, Tore Ola; Laberg, Jan Sverre (Chronicle; Kronikk, 2010-09-25)
    • Unravelling key controls on the rift climax to post-rift fill of marine rift basins: insights from 3D seismic analysis of the Lower Cretaceous of the Hammerfest Basin, SW Barents Sea 

      Marin Restrepo, Dora Luz; Escalona Varela, Alejandro; Grundvåg, Sten-Andreas; Olaussen, Snorre; Sandvik, Sara; Śliwińska, Kasia K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-19)
      In this study, we investigate key factors controlling the rift climax to post‐rift marine basin fill. We use two‐ and three‐dimensional seismic data in combination with sedimentological core descriptions from the Hammerfest Basin, south‐western Barents Sea to characterize and analyse the tectonostratigraphy and seismic facies of the Lower Cretaceous succession. Based on our biostratigraphic analyses, ...
    • Variability of Acoustically Evidenced Methane Bubble Emissions Offshore Western Svalbard 

      Veloso-Alarcon, Mario E.; Jansson, Pär; De Batist, Marc; Minshull, Timothy A.; Westbrook, Graham K.; Pälike, Heiko; Bünz, Stefan; Wright, Ian; Greinert, Jens (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-22)
      Large reservoirs of methane present in Arctic marine sediments are susceptible to rapid warming, promoting increasing methane emissions. Gas bubbles in the water column can be detected, and flow rates can be quantified using hydroacoustic survey methods, making it possible to monitor spatiotemporal variability. We present methane (CH<sub>4</sub>) bubble flow rates derived from hydroacoustic data ...
    • Variability of present and past PAH concentrations in sediments of the SW Barents Sea 

      Junttila, Juho; Carroll, JoLynn; Dijkstra, Noortje (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-09)
      The concentration and distribution of polyaromatic hydrocarbons (PAHs) in surface and subsurface sediment samples from Tromsøflaket and Ingøydjupet, southwestern Barents Sea, were investigated in order to provide insight into the levels and origins of PAHs in a region with petroleum activities. PAH profiles in sediments were evaluated in context with sediment grain size and total organic carbon ...
    • Variations in benthic foraminiferal assemblages in the Tagus mud belt during the last 5700 years: Implications for Tagus River discharge 

      Dessandier, Pierre-Antoine; Bonnin, Jérôme; Malaizé, Bruno; Lambert, Clément; Tjallingii, Rik; Warden, Lisa; Sinninghe Damsté, Jaap S.; Kim, Jung-Hyun (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-31)
      We analyzed a 10-m sediment core retrieved at 82 m water depth off the coast of the Tagus River (Western Iberian Margin, Portugal) to investigate a linkage between variations in benthic foraminiferal assemblages and Tagus River discharge over the last 5700 years. Benthic foraminiferal assemblages were studied at high resolution in combination with the stable carbon and oxygen isotopic composition ...
    • Variations in gas and water pulses at an Arctic seep: fluid sources and methane transport 

      Hong, Wei-Li; Torres, Marta E.; Portnov, Aleksei D; Waage, Malin; Haley, B.; Lepland, Aivo (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-19)
      Methane fluxes into the oceans are largely dependent on the methane phase as it migrates upward through the sediments. Here we document decoupled methane transport by gaseous and aqueous phases in Storfjordrenna (offshore Svalbard) and propose a three‐stage evolution model for active seepage in the region where gas hydrates are present in the shallow subsurface. In a preactive seepage stage, solute ...
    • Variations in pockmark composition at the Vestnesa Ridge: Insights from marine controlled source electromagnetic and seismic data 

      Goswami, Bedanta K.; Weitemeyer, Karen A.; Bünz, Stefan; Minshull, Timothy A.; Westbrook, Graham K.; Ker, Stephan; Sinha, Martin C. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-10)
      The Vestnesa Ridge marks the northern boundary of a known submarine gas hydrate province in the west Svalbard margin. Several seafloor pockmarks at the eastern segment of the ridge are sites of active methane venting. Until recently, seismic reflection data were the main tool for imaging beneath the ridge. Coincident controlled source electromagnetic (CSEM), high‐resolution two‐dimensional (2‐D) ...