Viser treff 227-246 av 710

    • Fracture-controlled fluid transport supports microbial methane-oxidizing communities at Vestnesa Ridge 

      Yao, Haoyi; Hong, Wei-Li; Panieri, Giuliana; Sauer, Simone; Torres, Marta E.; Lehmann, Moritz F.; Gründger, Friederike; Niemann, Helge (Journal article; Peer reviewed, 2019-05-29)
      We report a rare observation of a mini-fracture in near-surface sediments (30 cm below the seafloor) visualized using a rotational scanning X-ray of a core recovered from the Lomvi pockmark, Vestnesa Ridge, west of Svalbard (1200 m water depth). Porewater geochemistry and lipid biomarker signatures revealed clear differences in the geochemical and biogeochemical regimes of this core compared with ...
    • Frenulate siboglinids at high Arctic methane seeps and insight into high latitude frenulate distribution 

      Sen, Arunima; Didriksen, Alena; Hourdez, Stephane; Svenning, Mette Marianne; Rasmussen, Tine Lander (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-09)
      Frenulate species were identified from a high Arctic methane seep area on Vestnesa Ridge, western Svalbard margin (79°N, Fram Strait) based on mitochondrial cytochrome oxidase subunit I (mtCOI). Two species were found: <i>Oligobrachia haakonmosbiensis</i>, and a new, distinct, and undescribed <i>Oligobrachia</i> species. The new species adds to the cryptic <i>Oligobrachia</i> species complex found ...
    • Freshwater ostracods (Crustacea) and environmental variability of polygon ponds in the tundra of the Indigirka Lowland, north-east Siberia 

      Schneider, Andrea; Wetterich, Sebastian; Schirrmeister, Lutz; Herzschuh, Ulrike; Meyer, Hanno; Pestryakova, Luidmila A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
      Freshwater ostracods (Crustacea, Ostracoda) are valuable biological indicators. In Arctic environments, their habitat conditions are barely known and the abundance and diversity of ostracods is documented only in scattered records with incomplete ecological characterization. To determine the taxonomic range of ostracod assemblages and their habitat conditions in polygon ponds in the Indigirka Lowland, ...
    • From widespread Mississippian to localized Pennsylvanian extension in central Spitsbergen, Svalbard 

      Koehl, Jean-Baptiste P.; Muñoz-Barrera, Jhon M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-21)
      In the Devonian–Carboniferous, a rapid succession of clustered extensional and contractional tectonic events is thought to have affected sedimentary rocks in central Spitsbergen, Svalbard. These events include Caledonian post-orogenic extensional collapse associated with the formation of thick Early–Middle Devonian basins, Late Devonian–Mississippian Ellesmerian contraction, and Early–Middle ...
    • A Full-Stokes 3-D Calving Model Applied to a Large Greenlandic Glacier 

      Todd, Joe; Christoffersen, Poul; Zwinger, Thomas; Råback, Peter; Chauché, Nolwenn; Benn, Doug; Luckman, Adrian; Ryan, Johnny; Toberg, Nick; Slater, Donald; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-30)
      Iceberg calving accounts for around half of all mass loss from both the Greenland and Antarctic ice sheets. The diverse nature of calving and its complex links to both internal dynamics and climate make it challenging to incorporate into models of glaciers and ice sheets. Here we present results from a new open‐source 3‐D full‐Stokes calving model developed in Elmer/Ice. The calving model implements ...
    • 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 ...