Viser treff 667-686 av 698

    • 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 ...
    • Uncovering hidden structures: previously undescribed pseudopodia and ectoplasmic structures in planktonic foraminifera 

      Greco, Mattia; Westgård, Adele; Sykes, Freya Elizabeth; Mohamed, Mohamed Mahmoud Ezat Ahmed; Meilland, Julie (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-05)
      The trophic strategies of cold-water planktonic foraminifera are not well understood due to the challenge of culturing them in polar conditions. Here, we identify previously unknown ectoplasmic and cytoplasmic projections in three species of planktonic foraminifera thriving in polar and subpolar marine environments: Globigerina bulloides, Neogloboquadrina incompta and Neogloboquadrina pachyderma. ...
    • Underexplored continental shelf gateways: timing, mechanisms and role of SW Barents Sea Gateway, Norwegian Arctic 

      Lasabuda, Amando P. E.; Hanssen, Alfred; Laberg, Jan Sverre; Rydningen, Tom Arne; Patton, Henry; Faleide, Jan Inge; Abdelmalak, Mohamed Mansour; Kjølhamar, Bent (Conference object; Konferansebidrag, 2022)
      Ocean gateways connecting ocean basins are crucial for water and heat circulation, which influence global temperature, climate evolution and sediment distribution. While deep-water gateways have been a major research focus by the community, very little attention has been drawn to shallower gateways located on the continental shelves, where such circulation also takes place. In this study, we investigate ...
    • 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, ...
    • An updated Weichselian chronostratigraphic framework of the Kongsfjorden Trough Mouth Fan and its implications for the glacial history of Svalbard 

      Wiberg, Daniel Hesjedal; Haflidason, Haflidi; Laberg, Jan Sverre (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-02)
      The Arctic is a climate-sensitive area, responding rapidly to present changes, but for the past changes, the recordis still incomplete. Forinstance, theWeichselian glacial historyof the Svalbard–Barents Sea Ice Sheet (SBIS) haslargely been reconstructed based on studies of the fragmentary Spitsbergen terrestrial and shelf records. However, the sediments removed from the land and shelf areas during ...
    • Upper cretaceous-paleogene stratigraphy and development of the Mímir High, Vøring transform margin, Norwegian Sea 

      Polteau, Stephane; Planke, Sverre; Zastrozhnov, Dmitrii; Abdelmalak, Mohamed Mansour; Lebedeva-Ivanova, Nina; Eckhoff Planke, Ellen; Svensen, Henrik; Mazzini, Adriano; Gernigon, Laurent; Myklebust, Reidun; Kjølhamar, Bent; Pedersen, Rolf B.; Sandstå, Nils Rune; Bünz, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-19)
      Transform margins represent strike-slip type of plate boundaries that form during continental breakup and initial ocean opening. They are often characterized by margin-parallel highs with exposed pre- and syn-rift sequences. The Vøring Transform Margin, offshore mid-Norway, initiated in the earliest Eocene during the opening of the NE Atlantic. Here, 2D seismic reflection data reveal a transform ...
    • Using thermal UAV imagery to model distributed debris thicknesses and sub-debris melt rates on debris-covered glaciers 

      Bisset, Rosie R.; Nienow, Peter W.; Goldberg, Daniel N.; Wigmore, Oliver; Loayza-Muro, Raúl A.; Wadham, Jemma Louise; Macdonald, Moya L.; Bingham, Robert G. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-14)
      Supraglacial debris cover regulates the melt rates of many glaciers in mountainous regions around the world, thereby modifying the availability and quality of downstream water resources. However, the influence of supraglacial debris is often poorly represented within glaciological models, due to the absence of a technique to provide high-precision, spatially continuous measurements of debris thickness. ...
    • 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 ...
    • 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 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 ...
    • 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) ...
    • Ventilation history of Nordic Seas overflows during the last (de)glacial period revealed by species-specific benthic foraminiferal 14C dates 

      Mohamed, Ezat M.; Rasmussen, Tine L.; Thornalley, David J.R.; Olsen, Jesper; Skinner, Luke C.; Hönisch, Bärbel; Groeneveld, Jeroen (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-10)
      Formation of deep water in the high‐latitude North Atlantic is important for the global meridional ocean circulation, and its variability in the past may have played an important role in regional and global climate change. Here we study ocean circulation associated with the last (de)glacial period, using water‐column radiocarbon age reconstructions in the Faroe‐Shetland Channel, southeastern Norwegian ...
    • Visualizing and interpreting surface displacement patterns on unstable slopes using multi-geometry satellite SAR interferometry (2D InSAR) 

      Eriksen, Harald Øverli; Lauknes, Tom Rune; Larsen, Yngvar; Corner, Geoffrey D.; Bergh, Steffen G; Dehls, John; Kierulf, Halfdan Pascal (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-05)
      It is well known that satellite radar interferometry (InSAR) is capable of measuring surface displacement with a typical accuracy on the order of millimeters to centimeters. However, when the true deformation vector differs from the satellite line-of-sight (LOS), the sensitivity decreases and interpretation of InSAR deformationmeasurements becomes challenging. By combining displacement data ...
    • Visualizing tephra deposits and sedimentary processes in the marine environment: The potential of X-ray microtomography 

      Griggs, Adam J.; Davies, Siwan M.; Abbott, Peter M.; Coleman, Mark; Palmer, Adrian P.; Rasmussen, Tine Lander; Johnston, Richard (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-30)
      Localized tephra deposition in marine sequences is the product of many complex primary and secondary depositional processes. These can significantl y influence the potential applicability of tephra depos- its as isochronous marker horizons and current techniques, used in isolation, may be insufficient to fully unravel these processes. Here we demonstrate the innovative application of X-ray ...