Now showing items 841-860 of 1025

    • Distribution and characteristics of overdeepenings beneath the Greenland and Antarctic ice sheets: Implications for overdeepening origin and evolution 

      Patton, Henry; Swift, D.A.; Clark, C.D.; Livingstone, Stephen J.; Cook, S.J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-15)
      Glacier bed overdeepenings are ubiquitous in glacier systems and likely exert significant influence on ice dynamics, subglacial hydrology, and ice stability. Understanding of overdeepening formation and evolution has been hampered by an absence of quantitative empirical studies of their distribution and morphology, with process insights having been drawn largely from theoretical or numerical studies. ...
    • Linking the basement geology along the Africa-South America coasts in the South Atlantic 

      Konopasek, Jiri; Slama, Jiri; Košler, Jan (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-13)
      The match of geological units of the dissected Kaoko-Dom Feliciano-Gariep orogenic system exposed along the coasts of the South Atlantic is poorly understood. Two suites of intrusive rocks crop out in the Angra Fria Bay area, a part of the Coastal Terrane of the Kaoko Belt in Namibia. U–Pb zircon dating of three samples from the younger suite provided ages of 574 ± 6, 586 ± 3 and 584 ± 7 Ma, similar ...
    • Position, swimming direction and group size of fin whales (Balaenoptera physalus) in the presence of a fast-ferry in the Bay of Biscay 

      Aniceto, Ana Sofia Albuquerque Lima; Carroll, JoLynn; Tetley, Michael J; van Oosterhout, Cock (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-03-12)
      We analyze group size, swimming direction and the orientation of fin whales relative to a fast ferry in the Bay of Biscay. Fin whale groups (≥3 individuals) were on average closer to the vessel than single individuals and pairs (F1,114 = 4.94, p = 0.028) and were more often observed within a high-risk angle ahead of the ferry (binomial probability: p = 7.60 × 10−11). Also, small groups tend to swim ...
    • 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 ...
    • Extraordinary runoff from the Greenland ice sheet in 2012 amplified by hypsometry and depleted firn retention 

      Mikkelsen, A.B.; Hubbard, Alun Lloyd; MacFerrin, Mike; Box, Jason Eric; Doyle, Sam H.; Fitzpatrick, Andrew; Hasholt, Bent; Bailey, Hannah L.; Lindbäck, Katrin; Pettersson, Rickard (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-30)
      It has been argued that the infiltration and retention of meltwater within firn across the percolation zone of the Greenland ice sheet has the potential to buffer up to  ∼  3.6 mm of global sea-level rise (Harper et al., 2012). Despite evidence confirming active refreezing processes above the equilibrium line, their impact on runoff and proglacial discharge has yet to be assessed. Here, we compare ...
    • Past methane emissions in the earliest Pleistocene on Yermak Plateau, NW Svalbard. 

      Heimdal, Karianne (Master thesis; Mastergradsoppgave, 2016-05-15)
      Hole 912A (Ocean Drilling Program (ODP) Leg 151) drilled on the Yermak Plateau (eastern Arctic Ocean) is used to investigate past methane emissions in the earliest Pleistocene. Preliminary work showed depleted δ¹³C values at 93-96 meters below sea floor (mbsf), and an increase in methane concentration between 11, 5 and 23 mbsf. A secondary sampling focused on intervals between 10 and 23 mbsf (core ...
    • Ice sheet dynamics in the Brunt Basin, Weddell Sea, Antarctica, since the last glacial period 

      Sørli, Simon Helle (Master thesis; Mastergradsoppgave, 2016-11-15)
      High-resolution swath bathymetry, TOPAS sub-bottom profiles and four gravity cores from the Brunt Basin, southeastern Weddell Sea in Antarctica, were analysed with the purpose of reconstructing the ice sheet dynamics since the last glacial. Data collection was carried out by the British Antarctic Survey (BAS) and data analyses were carried out in a collaboration between the Department of Geosciences ...
    • Bretilbaketrekningshistorie og landformer foran Steindalsbreen, Lyngen, Troms 

      Nilsen, Carina (Master thesis; Mastergradsoppgave, 2016-06-15)
      Steindalen er lokalisert sør på Lyngenhalvøya, i Troms fylke. Steindalsbreen er en av de lettest tilgjengelige breer i området. Dette gjør breen til et yndet turmål, men det gjør det også lettere å studere en bre på nært hold. Undersøkelse av Steindalsbreen har foregått ved hjelp av feltturer til området, ved å studere foto og flybilder over området og ved å sammenstille data samlet over mange år, ...
    • Structure and flow properties of syn-rift border faults: The interplay between fault damage and fault-related chemical alteration (Dombjerg Fault, Wollaston Forland, NE Greenland) 

      Kristensen, Thomas B.; Rotevatn, Atle; Peacock, David C.P.; Henstra, Gijs A.; Midtkandal, Ivar; Grundvåg, Sten-Andreas (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-29)
      Structurally controlled, syn-rift, clastic depocentres are of economic interest as hydrocarbon reservoirs; understanding the structure of their bounding faults is of great relevance, e.g. in the assessment of fault-controlled hydrocarbon retention potential. Here we investigate the structure of the Dombjerg Fault Zone (Wollaston Forland, NE Greenland), a syn-rift border fault that juxtaposes syn-rift ...
    • Petrographic investigation of methane-derived authigenic carbonate crusts from Barents Sea and Norwegian Sea 

      Røde, Silje (Master thesis; Mastergradsoppgave, 2016-06-15)
      Methane-derived authigenic carbonate crusts from four seepage sites at the Loppa High in the southwestern Barents Sea, and one seepage site at Hola, off Vesterålen in the Norwegian Sea, have been investigated, with the main focus of understanding if and how the tests of benthic and planktonic foraminifera occurring in the crusts could serve as nucleation centers for the precipitated carbonates.
    • Paleoceanographic development in Leirdjupet, during the last deglaciation 

      Tønnessen, Lasse Aase (Master thesis; Mastergradsoppgave, 2016-08-23)
      The focus of this master thesis is to investigate the paleoenvironmental and paleoceanography during the last deglaciation in Leirdjupet, a small submarine trough in the southwestern Barents Sea. The lower half of the piston corer HH15-1303PC has been investigated for the distribution pattern of benthic foraminifera faunas, ice rafted debris (IRD), lithology and oxygen and carbon isotopes covering; ...
    • Reconstructions of paleoceanography and ice retreat based on benthic foraminifera, stable isotopes and sedimentological investigations from the northwestern Barents Sea south of Nordaustlandet, Svalbard 

      Eilertsen, Vårin Trælvik (Master thesis; Mastergradsoppgave, 2016-07-12)
      One gracity core NP05–11–49GC was retrieved from a 320 m water depth in the central part of Erik Eriksen Strait, south of Nordaustlandet, northwestern Barents Sea. The core was investigated for benthic foraminiferal distribution patterns, stable isotopes and sedimentological parameters in order to reconstruct the Late Weichselian deglaciation and Holocene paleoenvironment and paleoceanography of the ...
    • Metamorphic conditions in the Coastal-Punta del Este Terrane of the Kaoko-Dom Feliciano Belt in Namibia and Uruguay 

      Skagseth, Ida Grindal (Master thesis; Mastergradsoppgave, 2016-06-24)
      The metasediementary rocks of the Coastal Terrane in the Kaoko Belt (Namibia) and the meta-igneous rocks of the Punta del Este-Terrane in the Dom Feliciano Belt (Uruguay) both share one high-grade metamorphic event at approximately the same time of c. 650-630 Ma. Metamorphic conditions of this high-grade event were estimated in four samples from the Punta del Este Terrane and two samples from ...
    • Sedimentary ancient DNA from Lake Skartjørna, Svalbard: Assessing the resilience of arctic flora to Holocene climate change 

      Alsos, Inger Greve; Sjögren, Per Johan E.; Edwards, Mary E.; Landvik, Jon Y.; Gielly, Ludovic; Forwick, Matthias; Coissac, Eric; Brown, Antony G; Jakobsen, Leif Vidar; Merkel, Marie Kristine Føreid; Pedersen, Mikkel Winter (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-11)
    • Sea ice and millennial-scale climate variability in the Nordic seas 90 kyr ago to present 

      Hoff, Ulrike; Rasmussen, Tine Lander; Stein, Ruediger; Ezat, Mohamed; Fahl, Kirsten (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-07-26)
      In the light of rapidly diminishing sea ice cover in the Arctic during the present atmospheric warming, it is imperative to study the distribution of sea ice in the past in relation to rapid climate change. Here we focus on glacial millennial-scale climatic events (Dansgaard/Oeschger events) using the sea ice proxy IP25 in combination with phytoplankton proxy data and quantification of diatom species ...
    • Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere 

      Myhre, Cathrine Lund; Ferré, Benedicte; Platt, Stephen Matthew; Silyakova, Anna; Hermansen, Ove; Allen, Grant; Pisso, Ignacio; Schmidbauer, Josef Norbert; Stohl, Andreas; Pitt, Joseph R.; Jansson, Pær; Greinert, Jens; Percival, Carl; Fjæraa, Ann Mari; O'Shea, Sebastian J.; Gallagher, Martin; Le Breton, Michael; Bower, Keith N.; Bauguitte, Stéphane Jean-Bernard; Dalsøren, Stig Bjørløw; Vadakkepuliyambatta, Sunil; Fisher, Rebecca E.; Nisbet, Euan G.; Lowry, David; Myhre, Gunnar; Pyle, John Adrian; Cain, Michelle; Mienert, Jurgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-07)
      We find that summer methane (CH4) release from seabed sediments west of Svalbard substantially increases CH4 concentrations in the ocean but has limited influence on the atmospheric CH4 levels. Our conclusion stems from complementary measurements at the seafloor, in the ocean, and in the atmosphere from land-based, ship and aircraft platforms during a summer campaign in 2014. We detected high ...
    • Caledonian nappe emplacement: an example from Uløya, Northern Norway 

      Kraus, Katrin (Master thesis; Mastergradsoppgave, 2016-06-27)
      On Uløya, an island located east of the Lyngen peninsula in northern Troms, Norway, four Caledonian nappes are exposed. These are from bottom to top: part of the Kalak Nappe Complex (KNC), the Vaddas, the Kåfjord and the Nordmannvik nappe. In the present study the geology of these nappes is described, macroscopic and microscopic deformation structures are analyzed, and phase equilibrium modeling is ...
    • A structural, geomorphological and InSAR study of the unstable rock slope in Oksfjellet, Kåfjord, Troms 

      Bredal, Marie (Master thesis; Mastergradsoppgave, 2016-05-29)
      The main focus of this study has been to combine field observations of structural and geomorphological elements and interferometric synthetic aperture radar (InSAR) to investigate the unstable rock slope in Oksfjellet. The site is located along a NNE faced slope in a glacially eroded valley in Kåfjord, Troms. The Caledonian bedrock comprises mainly mica schists and display ductile (Caledonian) and ...
    • Analyses of Paleozoic and Mesozoic brittle fractures in West-Finnmark. Geometry, kinematics and relations to structures on the Finnmark Platform in the southwestern Barents Sea 

      Bergø, Espen (Master thesis; Mastergradsoppgave, 2016-06-12)
      This study focuses on Paleozoic and Mesozoic brittle faults and fractures found onshore and offshore in the northwestern areas of Finnmark, the Finnmark Platform, and the southwestern Barents Sea Margin. These structures have been mapped using software for mapping (ArcGIS 10.5 & Petrel 2013) and analyzing fault-fracture lineaments and faults from bathymetry, digital elevation models, satellite images, ...
    • Analysis of Late Paleozoic-Mesozoic brittle faults and fractures in West-Finnmark: geometry, kinematics, fault rocks and the relationship to offshore structures on the Finnmark Platform in the SW Barents Sea 

      Lea, Halldis (Master thesis; Mastergradsoppgave, 2016-05-29)
      The present work focuses on the onshore/offshore analysis and correlation of brittle faults and fractures on the Porsanger Peninsula area in west-Finnmark, the shelf areas and the immidiate offshore areas (Finnmark Platform and Gjesvær low). Structural field observation, microstructural and SEM analysis provide the basis for the characterization of the geometry, kinematics and fault rocks. This data ...