Now showing items 781-800 of 1121

    • Microseismicity linked to gas migration and leakage on the western Svalbard shelf 

      Franek, Peter; Plaza-Faverola, Andreia; Mienert, Jurgen; Bünz, Stefan; Ferré, Benedicte; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-26)
      The continental margin off Prins Karls Forland, western Svalbard, is characterized by widespread natural gas seepage into the water column at and upslope of the gas hydrate stability zone. We deployed an ocean bottom seismometer integrated into the MASOX (Monitoring Arctic Seafloor-Ocean Exchange) automated seabed observatory at the pinch-out of this zone at 389 m water depth to investigate passive ...
    • 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 ...
    • U-Th chronology and formation controls of methane-derived authigenic carbonates from the Hola trough seep area, northern Norway 

      Sauer, Simone; Knies, Jochen; Lepland, Aivo; Sahy, Diana; Martma, Tõnu; Noble, Stephen R.; Schönenbergerb, Jasmin; Klug, Martin; Schubert, Carsten J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-20)
      We investigated methane-derived authigenic carbonate (MDAC) crusts and nodules from a cold seep site on the northern Norwegian continental shelf in ca. 220 m water depth to determine the timing and mode of their formation. Gas bubbling observed during remotely operated vehicle (ROV)-assisted sampling of MDAC crusts revealed ongoing seep activity. Authigenic carbonates were present as crusts on the ...
    • Postglacial response of Arctic Ocean gas hydrates to climatic amelioration 

      Serov, Pavel; Vadakkepuliyambatta, Sunil; Mienert, Jurgen; Patton, Henry; Portnov, Aleksei D; Silyakova, Anna; Panieri, Giuliana; Carroll, Michael Leslie; Carroll, JoLynn; Andreassen, Karin; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-05)
      Seafloor methane release due to the thermal dissociation of gas hydrates is pervasive across the continental margins of the Arctic Ocean. Furthermore, there is increasing awareness that shallow hydrate-related methane seeps have appeared due to enhanced warming of Arctic Ocean bottom water during the last century. Although it has been argued that a gas hydrate gun could trigger abrupt climate ...
    • Ventilation history of Nordic Seas overflows during the last (de)glacial period revealed by species-specific benthic foraminiferal 14C dates 

      Mohamed, Ezat M.; Rasmussen, Tine L.; Thornalley, David J.R.; Olsen, Jesper; Skinner, Luke C.; Hönisch, Bärbel; Groeneveld, Jeroen (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-10)
      Formation of deep water in the high‐latitude North Atlantic is important for the global meridional ocean circulation, and its variability in the past may have played an important role in regional and global climate change. Here we study ocean circulation associated with the last (de)glacial period, using water‐column radiocarbon age reconstructions in the Faroe‐Shetland Channel, southeastern Norwegian ...
    • Relationship between mega-scale glacial lineations and iceberg ploughmarks on the Bjørnøyrenna Palaeo-Ice Stream bed, Barents Sea 

      Andreassen, Karin; Piasecka, Emilia D.; Stokes, Chris R.; Winsborrow, Monica C.M. (Journal article; Tidsskriftartikkel, 2018-02-24)
      Mega-scale glacial lineations (MSGLs) are ridge-groove corrugations aligned in the direction of the former ice flow, tens of kilometers long and up to a few hundred meters wide. They are the most striking subglacial features on the beds of former ice streams and play an important role in modulating ice flow through their influence on bed roughness and subglacial hydrology. Despite the importance of ...
    • Paleoenvironmental investigation of the northern flank of the Olga Basin (Barents Sea) during the Late Weichselian deglaciation 

      Patel, Jay (Master thesis; Mastergradsoppgave, 2018-06-11)
      Three gravity cores were collected from an unexplored site in the northern flank of the Olga Basin, Barents Sea. The lack of data from the central Barents Sea prompted this investigation and led to defining the evolution of the environment and ice sheet transitions over the Holocene. The three cores underwent benthic foraminiferal studies in combination with stable isotope analysis of (δ18O and δ ...
    • The regional Cretaceous development of the southeastern part of the Norwegian Barents Sea- from seismic interpretation 

      Heiberg, Vegard (Master thesis; Mastergradsoppgave, 2018-05-15)
      This study sheds new light on the regional Cretaceous development of the southeastern part of the Norwegian Barents Sea. The study area is in the former disputed area between Norway and Russia, which after the agreement on the new borders in 2010 was opened to petroleum activity in 2013. Consequently, the southeastern Barents Sea is still a frontier area with less scientific knowledge, compared to ...
    • Shallow methane hydrate system controls ongoing, downslope sediment transport in a low-velocity active submarine landslide complex, Hikurangi Margin, New Zealand 

      Mountjoy, J.J.; Pecher, Ingo; Henrys, Stuart; Crutchley, Gareth; Barnes, P.M.; Plaza-Faverola, Andreia (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-10-14)
    • Thermogenic methane injection via bubble transport into the upper Arctic Ocean from the hydrate-charged Vestnesa Ridge, Svalbard 

      Smith, Andrew James; Mienert, Jurgen; Bünz, Stefan; Greinert, Jens (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-04-21)
      We use new gas‐hydrate geochemistry analyses, echosounder data, and three‐dimensional P‐Cable seismic data to study a gas‐hydrate and free‐gas system in 1200 m water depth at the Vestnesa Ridge offshore NW Svalbard. Geochemical measurements of gas from hydrates collected at the ridge revealed a thermogenic source. The presence of thermogenic gas and temperatures of ∼3.3°C result in a shallow top of ...
    • Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane 

      Pohlman, John; Greinert, Jens; Ruppel, Carolyn; Silyakova, Anna; Vielstädte, Lisa; Casso, Michael; Mienert, Jürgen; Bünz, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-08)
      Continued warming of the Arctic Ocean in coming decades is projected to trigger the release of teragrams (1 Tg = 106 tons) of methane from thawing subsea permafrost on shallow continental shelves and dissociation of methane hydrate on upper continental slopes. On the shallow shelves (<100 m water depth), methane released from the seafloor may reach the atmosphere and potentially amplify global ...
    • Geofaglig kunnskap og holdninger til norsk petroleumsnæring. En casestudie av Alta/Gohta 

      Forsberg, Mariann (Master thesis; Mastergradsoppgave, 2018-05-15)
      Denne oppgaven har som hovedfokus å belyse holdninger og geofaglig kunnskap knyttet til norsk petroleumsnæring. Oppgaven tar utgangspunkt i olje- og gassfunnene Alta/Gohta i Barentshavet. Et geofaglig litteraturstudie har blitt gjennomført for å oppnå en forståelse av funnenes geologi og særegenheter. Intervjuer med norsk petroleumsnærings hovedaktører; olje- og energidepartementet, oljedirektoratet, ...
    • 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 ...
    • Identifying past petroleum exploration related drill cutting releases and influences on the marine environment and benthic foraminiferal communities, Goliat Field, SW Barents Sea, Norway 

      Sørensen, Steffen Aagaard; Junttila, Juho; Dijkstra, Noortje (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-01)
      The present multiproxy investigation of marine sediment cores aims at: 1) Identifying dispersion of petroleum exploration related drill cutting releases within the Goliat Field, Barents Sea in 2006/07 and 2) Assessing past and present influence of drill cuttings on the marine environment. The cores were recovered 5, 30, 60, 125 and 250 m from the drill site in the eastward downstream direction.<p> ...
    • CO2 flux over young and snow-covered Arctic pack ice in winter and spring 

      Nomura, Daiki; Granskog, Mats A.; Fransson, Agneta; Chierici, Melissa; Silyakova, Anna; Ohshima, Kay; Cohen, Lana; Delille, Bruno; Hudson, Stephen R.; Dieckmann, Gerhard (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-05)
      Rare CO2 flux measurements from Arctic pack ice show that two types of ice contribute to the release of CO2 from the ice to the atmosphere during winter and spring: young, thin ice with a thin layer of snow and older (several weeks), thicker ice with thick snow cover. Young, thin sea ice is characterized by high salinity and high porosity, and snow-covered thick ice remains relatively warm ( >  −7.5 °C) ...
    • 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 ...
    • Triassic Channel Systems on the northern Loppa High, SW Barents Sea 

      Arntzen, Marit (Master thesis; Mastergradsoppgave, 2018-06-07)
      During the Triassic, the Barents Sea Basin was filled with sediments from the Uralian and Caledonian mountain belts. High sediment yield and large river systems made progradation possible, resulting in an alluvial to deltaic plain stretching from the mountain belts in the south east to Spitsbergen in the north.This thesis focuses on the northwestern part of the Loppa High area, SW Barents Sea. The ...
    • The regional upper Paleozoic development of the SE part of the Norwegian Barents Sea - from seismic interpretation 

      Slettehaug, Hanne-Lise (Master thesis; Mastergradsoppgave, 2018-05-15)
      This thesis focuses on the Barents Sea South East (BSSE), and the overall goal has been to investigate the regional upper Paleozoic development in the SE part of the Barents Sea. After more than four decades of negotiation between Norway and Russia, a delineation agreement came in effect in 2011. Today, the area known as BSSE is opened up for petroleum operations. As part of the opening of the BSSE, ...
    • Ore petrography and fluid evolution in the Cu-(Zn) VMS deposits at Sulitjelma, Northern Norway 

      Birkeland, Andre (Master thesis; Mastergradsoppgave, 2018-05-29)
      The Sulitjelma deposits, Nordland, Northern Norway, with more than 20 Zn-Cu ore bodies (total tonnage excesses 35 Mt of ore at 1.84 % Cu, 0.86 % Zn, 10 g/t Ag and 0.25 g/t Au) have been described as a classic example of the Zn-Cu volcanogenic massive sulfide (VMS) mineralization. The mineralization is spatially associated with metamorphosed mafic rocks of Ordovician age. Both, ore bodies and their ...
    • The origin of quartz-carbonate veins hosted by ductile shear zones of the Astridal Supracrustal Belt, West-Troms Basement Complex. 

      Forslund, Thea Mathilde (Master thesis; Mastergradsoppgave, 2018-05-29)
      An approximately 1 meter wide NE-SW-oriented mylonitic shear zone hosts hydrothermally precipitated quartz and carbonate veins. The shear zone mainly consists of a secondary mylonitic fabric enriched in chlorite. A similar mylonitic shear zone striking NE-SW, oriented parallel to the axial plane of a F3-fold, consists of the same secondary mylonitic chloritized fabric and are therefore assumingly ...