Now showing items 93-112 of 315

    • Fault-controlled asymmetric landscapes and low-relief surfaces on Vestvågøya, Lofoten, North Norway: inherited Mesozoic rift-margin structures? 

      Bergh, Steffen G; Liland, Kristian; Corner, Geoffrey D.; Henningsen, Tormod; Lundekvam, Petter (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-20)
      The Lofoten Ridge is an integral basement horst of the hyperextended continental rift-margin off northern Norway. It is a key area for studying onshore–offshore rift-related faults, and for evaluating tectonic control on landscape development along the North Atlantic margin. This paper combines onshore geomorphological relief/aspect data and fault/fracture analysis with offshore bathymetric and ...
    • First record of catacrinid crinoid from the Lower Permian of Spitsbergen 

      Gorzelak, Przemyslaw; Blazejowski, Blazej; Uchman, Alfred; Hanken, Nils-Martin (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      An early Permian (late Artinskian–Roadian) cladid crinoid (Catacrinidae gen. et sp. indet.) is reported for the first time from the Vøringen Member of the Kapp Starostin Formation of Spitsbergen. The specimen is partly articulated and preserves a considerable part of its stalk and a complete cup, but only the proximal portions of its arms. Thus, it can− not be identified with any degree of ...
    • A flexural isostasy model for the Pleistocene evolution of the Barents Sea bathymetry 

      Zieba, Krzysztof Jan; Omosanya, Kamaldeen Olakunle; Knies, Jochen (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-01-24)
      The topographic relief of the Barents Sea was subjected to major changes during the past 1.5 million years mostly due to sediment redistribution driven by glacial activity. This paper addresses the problem of Pleistocene bathymetric evolution of the southern Barents Sea using a numerical modelling approach that considers the influence of regional isostasy on relief development. The model presented ...
    • Fluid flow and methane occurrences in the Disko Bugt area offshore West Greenland: indications for gas hydrates? 

      Nielsen, Tove; Laier, Troels; Kuijpers, Antoon; Rasmussen, Tine Lander; Mikkelsen, Naja E.; Nørgård-Pedersen, Niels (Journal article; Tidsskriftartikkel; Preprint; Manuskript, 2014-09-04)
      The present study is the first to directly address the issue of gas hydrates offshore West Greenland, where numerous occurrences of shallow hydrocarbons have been documented in the vicinity of Disko Bugt (Bay). Furthermore, decomposing gas hydrate has been implied to explain seabed features in this climate-sensitive area. The study is based on archive data and new (2011, 2012) shallow seismic and ...
    • Formation Conditions and 40Ar/39Ar Age of the Gem-Bearing Boqueirão Granitic Pegmatite, Parelhas, Rio Grande do Norte, Brazil 

      Strmic Palinkas, Sabina; Palinkaš, Ladislav A.; Neubauer, Franz; Scholz, Ricardo; Borojević Šoštarić, Sibila; Bermanec, Vladimir (Journal article; Peer reviewed, 2019-04-15)
      The Boqueirão granitic pegmatite, alias Alto da Cabeça pegmatite, is situated in Borborema Pegmatitic Province (BPP) in Northeast Brazil. This pegmatitic province hosts globally important reserves of tantalum and beryllium, as well as significant quantities of gemstones, including aquamarine, morganite, and the high-quality turquoise-blue “Paraíba Elbaite”. The studied lithium-cesium-tantalum Boqueirão ...
    • Formation of a large submarine crack during the final stage of retrogressive mass wasting on the continental slope offshore northern Norway 

      Laberg, Jan Sverre; Baeten, Nicole Jeanne; Lågstad, Petter Arthur; Forwick, Matthias; Vorren, Tore Ola (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-08-30)
      High-resolution swath-bathymetry data integrated with sub-bottom profiles and single-channel seismics reveal an 18 km long, up to 1000 m wide and 10-15 m deep crack located approx. 4 km upslope from a slide scar on the continental slope off northern Norway. This crack is formed by subsidence of the sea-floor sediments to a depth of 120 m due to downslope movement of a ~80 km2 large sediment slab ...
    • 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.; Grüdger, 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 ...
    • 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)
    • 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, ...