Now showing items 104-123 of 316

    • Gamle olje- og gass-lekkasjer i Barentshavet 

      Vorren, Tore Ola; Laberg, Jan Sverre (Chronicle; Kronikk, 2010-08-28)
    • Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data 

      Singhroha, Sunny; Bünz, Stefan; Plaza-Faverola, Andreia; Chand, Shyam (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-09-23)
      We have estimated the seismic attenuation in gas hydrate and free-gas-bearing sediments from high-resolution P-cable 3D seismic data from the Vestnesa Ridge on the Arctic continental margin of Svalbard. P-cable data have a broad bandwidth (20–300 Hz), which is extremely advantageous in estimating seismic attenuation in a medium. The seismic quality factor (Q), the inverse of seismic attenuation, ...
    • Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming 

      Wallmann, Klaus; Riedel, M.; Hong, Wei-Li; Patton, Henry; Hubbard, Alun Lloyd; Pape, T.; Hsu, C.W.; Schmidt, C.; Johnson, Joel E.; Torres, M.E.; Andreassen, Karin; Berndt, C.; Bohrmann, G (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-08)
      Methane seepage from the upper continental slopes of Western Svalbard has previously been attributed to gas hydrate dissociation induced by anthropogenic warming of ambient bottom waters. Here we show that sediment cores drilled off Prins Karls Foreland contain freshwater from dissociating hydrates. However, our modeling indicates that the observed pore water freshening began around 8 ka BP when ...
    • Gas hydrate stability zone of the Barents Sea and Kara Sea region 

      Klitzke, Peter; Luzi-Helbing, Manja; Schicks, Judith M.; Cacace, Mauro; Jacquey, Antoine B.; Scheck-Wenderoth, Magdalena; Faleide, Jan Inge (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-29)
      In this study we assess the present-day gas hydrate stability zone for the Barents Sea and Kara Sea region. Thereby, we make use of a data-based 3D lithosphere-scale pressure and thermal model. The resulting gas hydrate stability zone varies within >1km across the study area and strongly correlates with the local geological settings and the corresponding geothermal gradient. Gas hydrates containing ...
    • Geochemical characterisation of northern Norwegian fjord surface sediments: A baseline for further paleo-environmental investigations 

      Faust, Johan Christoph; Scheiber, Thomas; Fabian, Karl; Vogt, Christoph; Knies, Jochen (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-08-26)
      Norwegian fjord sediments are promising archives for very high resolution records of past environmental changes. Recent investigations of the modern depositional environment within fjords revealed that the accurate quantification of the inputs, sources, and sedimentary preservation of organic and inorganic material is crucial to decipher long term past climate signals in the sedimentary record ...
    • Geologi og klimaendringer 

      Andreassen, Karin (Conference object; Konferansebidrag, 2010-09-02)
    • Geological controls on fluid flow and gas hydrate pingo development on the Barents Sea margin 

      Waage, Malin; Portnov, Aleksei D; Serov, Pavel; Bünz, Stefan; Waghorn, Kate Alyse; Vadakkepuliyambatta, Sunil; Mienert, Jurgen; Andreassen, Karin (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-16)
      In 2014, the discovery of seafloor mounds leaking methane gas into the water column in the northwestern Barents Sea became the first to document the existence of non‐permafrost related gas hydrate pingos (GHP) on the Eurasian Arctic shelf. The discovered site is given attention because the gas hydrates occur close to the upper limit of the gas hydrate stability, thus may be vulnerable to climatic ...
    • Geological modelling for investigating CO2 emissions in Florina Basin, Greece 

      Koukuzas, N.; Tasianas, Alexandros; Gemeni, V; Alexopoulos, D.; Vasilatos, Charalampos (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-15)
      This paper presents an investigation of naturally occurring CO2 emissions from the Florina natural analogue site in Greece. The main objective was to interpret previously collected depth sounding data, convert them into surfaces, and use them as input to develop, for the rst time, 3D geological models of the Florina basin. By also locating the extent of the aquifer, the location of the CO2 ...
    • Geophysical and geochemical controls on the megafaunal community of a high Arctic cold seep 

      Sen, Arunima; Åström, Emmelie Karin Linnea; Hong, Wei-Li; Portnov, Aleksei D; Waage, Malin; Serov, Pavel; Carroll, Michael Leslie; Carroll, JoLynn (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-25)
      Cold-seep megafaunal communities around gas hydrate mounds (pingos) in the western Barents Sea (76°N, 16°E,  ∼ 400 m depth) were investigated with high-resolution, geographically referenced images acquired with an ROV and towed camera. Four pingos associated with seabed methane release hosted diverse biological communities of mainly nonseep (background) species including commercially important fish ...
    • Geophysical constraints on the dynamics and retreat of the Barents Sea ice sheet as a palaeobenchmark for models of marine icesheet deglaciation 

      Patton, Henry; Andreassen, Karin; Bjarnadóttir, Lilja Rún; Dowdeswell, J.A.; Winsborrow, Monica; Noormets, Riko; Polyak, Leonid; Auriac, A.; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-14)
      Our understanding of processes relating to the retreat of marine-based ice sheets, such as the West Antarctic Ice Sheet and tidewater-terminating glaciers in Greenland today, is still limited. In particular, the role of ice-stream instabilities and oceanographic dynamics in driving their collapse are poorly constrained beyond observational timescales. Over numerous glaciations during the Quaternary, ...
    • Glacial isostatic adjustment associated with the Barents Sea ice sheet: A modelling inter-comparison 

      Auriac, Amandine; Whitehouse, P.L.; Bentley, M.J.; Patton, Henry; Lloyd, J.M.; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-01)
      The 3D geometrical evolution of the Barents Sea Ice Sheet (BSIS), particularly during its late-glacial retreat phase, remains largely ambiguous due to the paucity of direct marine- and terrestrial-based evidence constraining its horizontal and vertical extent and chronology. One way of validating the numerous BSIS reconstructions previously proposed is to collate and apply them under a wide range ...
    • Glacigenic sedimentation pulses triggered postglacial gas hydrate dissociation 

      Karstens, Jens; Haflidason, Haflidi; Becker, Lukas W.M.; Berndt, Christian; Rüpke, Lars; Planke, Sverre; Liebetrau, Volker; Schmidt, Markus; Mienert, Jürgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-02-12)
      Large amounts of methane are stored in continental margins as gas hydrates. They are stable under high pressure and low, but react sensitively to environmental changes. Bottom water temperature and sea level changes were considered as main contributors to gas hydrate dynamics after the last glaciation. However, here we show with numerical simulations that pulses of increased sedimentation dominantly ...
    • Greenland Ice Sheet surface melt amplified by snowline migration and bare ice exposure 

      Ryan, J.C.; Smith, L.C.; Van As, D.; Cooley, S.W.; Cooper, M.G.; Pitcher, L.H.; Hubbard, A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-06)
      Greenland Ice Sheet mass loss has recently increased because of enhanced surface melt and runoff. Since melt is critically modulated by surface albedo, understanding the processes and feedbacks that alter albedo is a prerequisite for accurately forecasting mass loss. Using satellite imagery, we demonstrate the importance of Greenland’s seasonally fluctuating snowline, which reduces ice sheet albedo ...
    • Grounding line proximal sediment characteristics at a marine-based, late-stage ice stream margin 

      Rüther, Denise Christina; Winsborrow, Monica; Andreassen, Karin; Forwick, Matthias (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-12)
      Geomorphological evidence suggests that ice streams undergo frequent dynamic changes towards the end of their life cycles, but the associated sedimentary characteristics and processes remain poorly understood. Here, we present new sedimentological data from a Late Weichselian marine‐based ice stream in upper Bjørnøyrenna, northern Barents Sea, which experienced accelerated flow, intense calving of ...
    • High-resolution 3D seismic exhibits new insights into the middle-late Pleistocene stratigraphic evolution and sedimentary processes of the Bear Island trough mouth fan 

      Waage, Malin; Bünz, Stefan; Bøe, Reidulv; Mienert, Jurgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-21)
      Arctic Ocean trough mouth fans (TMFs) represent a valuable archive of glacial-interglacial sedimentary processes that are especially important when reconstructing pre-Weichselian glaciations that may lack distinct imprints on the shelves. In 2011, we acquired the first high-resolution 3D seismic cube (~3 m vertical and 6 m horizontal resolution) on the continental slope of the SW Barents Sea by use ...
    • High-resolution 3D seismic study of pockmarks and shallow fluid flow systems at the Snøhvit hydrocarbon field in the SW Barents Sea 

      Tasianas, Alexandros; Bünz, Stefan; Bellwald, Benjamin; Hammer, Øyvind; Planke, Sverre; Lebedeva-Ivanova, Nina; Krassakis, Pavlos (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-21)
      The Barents Sea is an epicontinental shelf sea with a fragmented structure consisting of long fault complexes, basins and basement highs. Fluid leakage from deep-seated hydrocarbon accumulations is a widespread phenomenon and mostly related to its denudation history during the glacial/interglacial cycles. In this study, we aimed to better understand shallow fluid flow processes that have led to the ...
    • A High-Resolution Geomagnetic Relative Paleointensity Record From the Arctic Ocean Deep-Water Gateway Deposits During the Last 60 kyr 

      Caricchi, Chiara; Lucchi, Renata Giulia; Sagnotti, Leonardo; Macri, Patrizia; Di Roberto, Alessio; Del Carlo, Paola; Husum, Katrine; Laberg, Jan Sverre; Morigi, Caterina (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-16)
      We present a paleomagnetic and rock magnetic data set from two long sediment cores collected from Bellsund and Isfjorden contourite drifts located on the eastern side of the Fram Strait (western Spitsbergen margin). The data set gave the opportunity to define the behavior of the past geomagnetic field at high latitude and to constrain the palaeoclimatic events that occurred in a time framework ...
    • High-resolution landform assemblage along a buried glacio-erosive surface in the SW Barents Sea revealed by P-Cable 3D seismic data 

      Bellwald, Benjamin; Planke, Sverre; Lebedeva-Ivanova, Nina; Piasecka, Emilia Daria; Andreassen, Karin (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-01)
      The Quaternary sedimentary record in the Arctic captures a diverse and evolving range of landscapes reflecting cli-mate changes. Here we study the geological landform assemblage of the Upper Regional Unconformity (URU) in theSW Barents Sea. The aims are (i) to characterize buried geological landforms on a meter-scale resolution, (ii) to un-derstand their link with underlying structures, and (iii) ...
    • High-resolution underwater laser spectrometer sensing provides new insights into methane distribution at an Arctic seepage site 

      Jansson, Pär; Triest, Jack; Grilli, Roberto; Ferré, Benedicte; Silyakova, Anna; Mienert, Jurgen; Chappellaz, Jérôme (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-13)
      Methane (CH4) in marine sediments has the potential to contribute to changes in the ocean and climate system. Physical and biochemical processes that are difficult to quantify with current standard methods such as acoustic surveys and discrete sampling govern the distribution of dissolved CH4 in oceans and lakes. Detailed observations of aquatic CH4 concentrations are required for a better understanding ...
    • The history and future trends of ocean warming-induced gas hydrate dissociation in the SW Barents Sea 

      Vadakkepuliyambatta, Sunil; Chand, Shyam; Bünz, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-01-13)
      The Barents Sea is a major part of the Arctic where the Gulf Stream mixes with the cold Arctic waters. Late Cenozoic uplift and glacial erosion have resulted in hydrocarbon leakage from reservoirs, evolution of fluid flow systems, shallow gas accumulations, and hydrate formation throughout the Barents Sea. Here we integrate seismic data observations of gas hydrate accumulations along with gas hydrate ...