Viser treff 228-247 av 698

    • Gamle olje- og gass-lekkasjer i Barentshavet 

      Vorren, Tore Ola; Laberg, Jan Sverre (Chronicle; Kronikk, 2010-08-28)
    • Garnet growth and mineral geochronology constrains the diachronous Neoproterozoic convergent evolution of the southern Dom Feliciano Belt, Uruguay 

      Percival, Jack James; Konopásek, Jiří; Oyhantçabal, Pedro; Slama, Jiri; Anczkiewicz, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-15)
      The Dom Feliciano Belt of southern Brazil and Uruguay represents part of a larger Neoproterozoic orogenic system formed during the amalgamation of Western Gondwana. The hinterland and foreland domains in parts of the belt preserve deformation structures and metamorphic assemblages that developed during early crustal thickening from c. 650 Ma. However, the metamorphic history of the southern foreland, ...
    • 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 ...
    • Gas seeps in Norwegian waters – distribution and mechanisms 

      Thorsnes, Terje; Chand, Shyam; Bellec, Valerie Karin; Nixon, Chantel; Brunstad, Harald; Lepland, Aivo; Aarrestad, Sigrun M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-01)
      Gas seeps and fluid-flow related seabed features are found over the entire Norwegian exclusive economic zone (EEZ). Multibeam water-column data from c. 136 000 km2 has revealed more than 5 000 gas seeps. Most of the gas seeps seem to have biogenic, thermogenic or mixed origin; some may be of abiotic origin. The spatial distribution of the gas seeps appears to correlate with: 1 – structural highs ...
    • GEO-3144/8144 Teaching Cruise: Geologically controlled hydrocarbon seepage in Hopendjupet and the wider Barents Sea 

      Serov, Pavel; Patton, Henry; Mazzini, Adriano; Mattingsdal, Rune; Shephard, Grace; Cooke, Frances Ann; Martins de Aguiar, Victor Cesar; Holm, Villads Dyrved; Alessandrini, Giuliana; Meza Cala, Juan Camilo; Luerssen, Paula (Research report; Forskningsrapport, 2022-11-18)
      The CAGE22-6 cruise on-board R/V Helmer Hanssen hosted UiT´s Arctic Marine Geology and Geophysics (GEO-8144 and GEO-3144) field course for PhD and Master students, and was carried out in collaboration with NPD – the Norwegian Petroleum Directorate and the INTPART project HOTMUD based at Centre for Earth Evolution and Dynamics (CEED) the University of Oslo. The cruise was also a part of the UNESCO ...
    • 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 ...
    • Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea 

      Semenov, Petr; Portnov, Aleksei D; Krylov, Alexey; Egorov, Alexander V; Vanshtein, Boris (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-16)
      Driven by rising bottom water temperatures, the thawing of subsea permafrost leads to an increase in fluid flow intensity in shallow marine sediments and results in the emission of methane into the water column. Limiting the release of permafrost-related gas hydrates and permafrost- sequestered methane into the global carbon cycle are of primary importance to the prevention of future Arctic Ocean ...
    • Geochronology and chemostratigraphy of the 2.47–1.96 Ga rift-related volcano-sedimentary succession in the Karasjok Greenstone Belt, northern Norway, and its regional correlation within the Fennoscandian Shield 

      Hansen, Harald; Slagstad, Trond; Bergh, Steffen Gunnar; Bekker, Andrey (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-09)
      New geochronological data for the amphibolite-facies volcano-sedimentary Karasjok Greenstone Belt in northwestern Fennoscandia bracket its age between 2.47 and 1.96 Ga. The volcano-sedimentary units were deposited on the 3005 24 to 2776 69 Ma crystalline basement rocks of the Jergul Gneiss Complex. The lowermost Vuomegielas Formation contains rhyodacites dated at 2469 12 Ma that were deposited in ...
    • Geologi og klimaendringer 

      Andreassen, Karin (Conference object; Konferansebidrag, 2010-09-02)
    • Geological controls of giant crater development on the Arctic seafloor 

      Waage, Malin; Serov, Pavel; Andreassen, Karin; Waghorn, Kate Alyse; Bünz, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-21)
      Active methane seepage occurs congruent with a high density of up to 1 km-wide and 35 m deep seafloor craters (>100 craters within 700 km<sup>2</sup> area) within lithified sedimentary rocks in the northern Barents Sea. The crater origin has been hypothesized to be related to rapid gas hydrate dissociation and methane release around 15–12 ka BP, but the geological setting that enabled and possibly ...
    • 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 ...
    • Geomorphology and development of a high-latitude channel system: the INBIS channel case (NW Barents Sea, Arctic) 

      Rui, L.; Rebesco, M.; Casamor, J.L.; Laberg, Jan Sverre; Rydningen, Tom Arne; Caburlotto, A.; Forwick, Matthias; Urgeles, R.; Accettella, D.; Lucchi, R. G.; Delbono, I.; Barsanti, M.; Demarte, M.; Ivaldi, R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-25)
      The INBIS (Interfan Bear Island and Storfjorden) channel system is a rare example of a deep-sea channel on a glaciated margin. The system is located between two trough mouth fans (TMFs) on the continental slope of the NW Barents Sea: the Bear Island and the Storfjorden–Kveithola TMFs. New bathymetric data in the upper part of this channel system show a series of gullies that incise the shelf break ...
    • Geomorphology and surficial geology of the Femmilsjøen area, northern Spitsbergen 

      Allaart, Lis; Schomacker, Anders; Håkansson, Lena; Farnsworth, Wesley R.; Brynjólfsson, Skafti; Grumstad, Andreas; Kjellman, Sofia Elisabeth (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-09)
      Climate change is amplified in the Arctic, and establishing baseline data for its current character is important. Here we present a map of the geomorphology of the Femmilsjøen area, Spitsbergen, northern Svalbard. The regional physiography is characterised by a low-relief, high elevation mountain plateau, its high-relief steep slopes, and low-relief coastal lowlands. The results indicate that glaciers ...
    • 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 and environmental changes in northern Svalbard over the last 16.3 ka inferred from neodymium isotopes 

      Jang, Kwangchul; Ahn, Youngkyu; Joe, Young Jin; Braun, Carmen; Joo, Young Ji; Kim, Jung-Hyun; Bayon, Germain; Forwick, Matthias; Vogt, Christoph; Nam, Seung-Il (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-05)
      The reconstruction of past ice sheet extents and dynamics in polar regions is essential for understanding the global climate system and obtaining more reliable predictions of future climate change. Here, we present a multi-proxy dataset integrating the Nd isotopic compositions (εNd) of paired detrital and authigenic Fe oxide fractions, grain size distributions, organic geochemistry, and mineral ...
    • Glacial history and depositional environments in little Storfjorden and Hambergbukta of Arctic Svalbard since the younger dryas 

      Joe, Young Jin; Jang, Kwangchul; Forwick, Matthias; Laberg, Jan Sverre; Kong, Gee Soo; Kang, Moo-Hee; Yoon, Seok-Hoon; Nam, Seung-Il (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-21)
      Geophysical and lithological data provide crucial information for the understanding of glacial history in Arctic Svalbard. In this study, we reconstructed the glacier-induced depositional environments of Little Storfjorden and its tributary, Hambergbukta, over the last 13 ka to better understand the glacial history of southeastern Svalbard. The combined uses of swath-bathymetry, high-resolution ...