Now showing items 164-183 of 316

    • Magnetotelluric signatures of the complex tertiary fold–thrust belt and extensional fault architecture beneath Brøggerhalvøya, Svalbard 

      Beka, Thomas Ibsa; Bergh, Steffen G; Smirnov, Maxim; Birkelund, Yngve (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-18)
      Magnetotelluric (MT) data were recently collected on Brøggerhalvøya, Svalbard, in a 0.003–1000 s period range along a curved WNW–ESE profile. The collected data manifested strong three-dimensional (3D) effects. We modelled the full impedance tensor with tipper and bathymetry included in 3D, and benchmarked the result with determinant data two-dimensional (2D) inversion. The final inversion results ...
    • Meter-Scale 3D Seismic Data for High-Resolution Site Characterization 

      Lebedeva-Ivanova, Nina; Polteau, Stephane; Zastrozhnov, Dmitry; Planke, Sverre; Waage, Malin; Bünz, Stefan; Bellwald, Benjamin; Vanneste, Maarten; Sauvin, Guillaume; Myklebust, R. (Conference object; Konferansebidrag, 2019-06-03)
      High-resolution 3D site characterization can deliver reliable quantitative property volumes of the subsurface when based on seismic data able to image meter-sized objects. Following the theoretical analysis of seismic wave propagation in the shallow sub-surface, we present case studies based on re-processing of 3D P-Cable seismic data. The case study of data re-processing from the Vestnesa Ridge ...
    • Methane at Svalbard and over the European Arctic Ocean 

      Platt, Stephen Matthew; Eckhardt, Sabine; Ferré, Benedicte; Fisher, Rebecca E.; Hermansen, Ove; Jansson, Pär; Lowry, David; Nisbet, Euan G.; Pisso, Ignacio; Schmidbauer, Norbert; Silyakova, Anna; Stohl, Andreas; Svendby, Tove Marit; Vadakkepuliyambatta, Sunil; Mienert, Jurgen; Myhre, Cathrine Lund (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-05)
      Methane (CH<sub>4</sub>) is a powerful greenhouse gas. Its atmospheric mixing ratios have been increasing since 2005. Therefore, quantification of CH<sub>4</sub> sources is essential for effective climate change mitigation. Here we report observations of the CH<sub>4</sub> mixing ratios measured at the Zeppelin Observatory (Svalbard) in the Arctic and aboard the research vessel (RV) Helmer Hanssen ...
    • Methane cold seeps as biological oases in the high-Arctic deep sea 

      Åström, Emmelie; Carroll, Michael Leslie; Ambrose, William; Sen, Arunima; Silyakova, Anna; Carroll, JoLynn (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-27)
      Cold seeps can support unique faunal communities via chemosynthetic interactions fueled by seabed emissions of hydrocarbons. Additionally, cold seeps can enhance habitat complexity at the deep seafloor through the accretion of methane derived authigenic carbonates (MDAC). We examined infaunal and megafaunal community structure at high-Arctic cold seeps through analyses of benthic samples and ...
    • Methane release from pingo-like features across the South Kara Sea shelf, an area of thawing offshore permafrost 

      Serov, Pavel; Portnov, Aleksei D; Mienert, Jurgen; Semenov, Peter; Ilatovskaya, Polonia (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-16)
      The Holocene marine transgression starting at ~19 ka flooded the Arctic shelves driving extensive thawing of terrestrial permafrost. It thereby promoted methanogenesis within sediments, the dissociation of gas hydrates, and the release of formerly trapped gas, with the accumulation in pressure of released methane eventually triggering blowouts through weakened zones in the overlying and thinned ...
    • Methane seepage at Vestnesa Ridge (NW Svalbard) since the Last Glacial Maximum 

      Schneider, Andrea; Panieri, Giuliana; Lepland, Aivo; Consolaro, Chiara; Crémière, Antoine; Forwick, Matthias; Johnson, J.E.; Plaza-Faverola, Andreia; Sauer, Simone; Knies, Jochen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-21)
      <p>Multiple proxies in the geological record offshore NW Svalbard track shallow subseafloor diagenesis and seafloor methane seepage during the Last Glacial Maximum (LGM) extent and the disintegration of the Svalbard Barents Sea Ice Sheet (SBIS). Vestnesa Ridge, located at 79°N and in 1200 m water depth, is one of the northernmost known active methane seep sites and is characterised by a subseafloor ...
    • Methane- and dissolved organic carbon-fueled microbial loop supports a tropical subterranean estuary ecosystem 

      Brankovits, D.; Pohlman, J.W.; Niemann, Helge; Leigh, M.B.; Leewis, M.C.; Becker, K.W.; Iliffe, F.A.; Lehmann, M.F.; Phillips, B. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-28)
      Subterranean estuaries extend inland into density-stratified coastal carbonate aquifers containing a surprising diversity of endemic animals (mostly crustaceans) within a highly oligotrophic habitat. How complex ecosystems (termed anchialine) thrive in this globally distributed, cryptic environment is poorly understood. Here, we demonstrate that a microbial loop shuttles methane and dissolved organic ...
    • Methane-fuelled biofilms predominantly composed of methanotrophic ANME-1 in Arctic gas hydrate-related sediments 

      Gründger, Friederike; Carrier, Vincent; Svenning, Mette Marianne; Panieri, Giuliana; Vonnahme, Tobias R.; Klasek, Scott; Niemann, Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-05)
      Sedimentary biofilms comprising microbial communities mediating the anaerobic oxidation of methane are rare. Here, we describe two biofilm communities discovered in sediment cores recovered from Arctic cold seep sites (gas hydrate pingos) in the north-western Barents Sea, characterized by steady methane fluxes. We found macroscopically visible biofilms in pockets in the sediment matrix at the depth ...
    • Microbial methane formation in deep aquifers of a coal-bearing sedimentary basin, Germany 

      Gründger, Friederike; Jimenez, N.; Thielemann, T.; Straaten, N.; Lüders, T.; Richnow, H. H.; Krüger, M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-20)
      Coal-bearing sediments are major reservoirs of organic matter potentially available for methanogenic subsurface microbial communities. In this study the specific microbial community inside lignite-bearing sedimentary basin in Germany and its contribution to methanogenic hydrocarbon degradation processes was investigated. The stable isotope signature of methane measured in groundwater and coal-rich ...
    • 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 ...
    • Middle to Late Devonian–Carboniferous collapse basins on the Finnmark Platform and in the southwesternmost Nordkapp basin, SW Barents Sea 

      Koehl, Jean-Baptiste; Bergh, Steffen G; Henningsen, Tormod; Faleide, Jan Inge (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-28)
      The SW Barents Sea margin experienced a pulse of extensional deformation in the Middle–Late Devonian through the Carboniferous, after the Caledonian Orogeny terminated. These events marked the initial stages of formation of major offshore basins such as the Hammerfest and Nordkapp basins. We mapped and analyzed three major fault complexes, (i) the Måsøy Fault Complex, (ii) the Rolvsøya fault, and ...
    • Middle to late Holocene paleoproductivity reconstructions for the western Barents Sea: a model-data comparison 

      Pathirana, Irene Dorothea; Knies, Jochen; Felix, Maarten; Mann, U.; Ellingsen, Ingrid H. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-30)
      In this study we focus on late Holocene primary productivity (PP) variability in the western Barents Sea and its response to variable sea ice coverage by combining PP reconstructed from several sediment cores with regional PP trends simulated with a well-constrained organic facies model, OF-Mod 3D. We find that modern production rates reconstructed from buried marine organic matter ...
    • Mineralogical and Geochemical Constraints on Magma Evolution and Late-Stage Crystallization History of the Breivikbotn Silicocarbonatite, Seiland Igneous Province in Northern Norway: Prerequisites for Zeolite Deposits in Carbonatite Complexes 

      Zozulya, Dmitry R.; Kullerud, Kåre; Ravna, Erling Krogh; Savchenko, Yevgeny E.; Selivanova, Ekaterina A.; Timofeeva, Marina G. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-20)
      The present work reports on new mineralogical and whole-rock geochemical data from the Breivikbotn silicocarbonatite (Seiland igneous province, North Norway), allowing conclusions to be drawn concerning its origin and the role of late fluid alteration. The rock shows a rare mineral association: calcite + pyroxene + amphibole + zeolite group minerals + garnet + titanite, with apatite, allanite, ...
    • The Miocene-Pliocene boundary and the Messinian Salinity Crisis in the easternmost Mediterranean: Insights from the Hatay Graben (Southern Turkey) 

      Boulton, Sarah J.; Smart, Christopher W.; Consolaro, Chiara; Snider, Avalon (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-02)
      The Hatay Graben is one of three easternmost basins in the Mediterranean that preserve sediments that span the Miocene–Pliocene boundary, including gypsums from the Messinian Salinity Crisis (MSC). Here we integrate existing data and present new sedimentological and micropalaeontological data to investigate the palaeoenvironments of late Miocene to early Pliocene deposits and place this important ...
    • Mississippian rocks and WNW–ESE-striking faults in Spitsbergen 

      Koehl, Jean-Baptiste P. (Conference object; Konferansebidrag; Preprint, 2019-06-18)
    • Modelling persistent methane seepage offshore western Svalbard since early Pleistocene 

      Knies, Jochen; Daszinnies, Matthias Christian; Plaza-Faverola, Andreia; Chand, Shyam; Sylta, Øyvind; Bünz, Stefan; Johnson, Joel E; Mattingsdal, Rune; Mienert, Jurgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-31)
      Recent observations of extensive methane release into the oceans and atmosphere have raised concern as to whether rising temperatures across the Arctic could drive rapid destabilization of gas hydrate reservoirs. Here, we report modelling results from hydrate-modulated methane seepage from Vestnesa Ridge, offshore western Svalbard, suggesting that continuous leakage has occurred from the seafloor ...
    • Monitoring marine mammals using unmanned aerial vehicles: quantifying detection certainty 

      Aniceto, Ana Sofia; Biuw, Martin; Lindstrøm, Ulf; Solbø, Stian; Broms, Fredrik Björn; Carroll, JoLynn (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-08)
      Unmanned aerial vehicles (UAVs) are increasingly being recognized as potentially useful for detection of marine mammals in their natural habitats, but an important consideration is the associated uncertainties in animal detection. We present a study based on field trials using UAVs to carry out image‐based monitoring of cetaceans in two fjords in northern Norway. We conducted 12 missions to assess ...
    • Monitoring Of CO2 Leakage Using High-Resolution 3D Seismic Data – Examples From Snøhvit, Vestnesa Ridge And The Western Barents Sea 

      Bellwald, Benjamin; Waage, Malin; Planke, S; Lebedeva-Ivanova, Nina; Polteau, S; Tasianas, Alexandros; Bünz, Stefan; Plaza-Faverola, Andreia; Berndt, Christian; Stokke, H.H.; Millett, John; Myklebust, R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-21)
      Injection of CO2 in subsurface reservoirs may cause overburden deformation and CO2 leakage. The aim of this study is to apply technologies for detection and monitoring of CO2 leakage and deformation above the injection reservoirs. The examples of this study include data from the Vestnesa Ridge natural seep site, the Snøhvit gas field and CO2 storage site region, and the Gemini North gas reservoir. ...
    • Morphological evidence for marine ice stream shutdown, central Barents Sea 

      Kurjanski, Bartosz; Rea, Brice R.; Spagnolo, Matteo; Winsborrow, Monica; Cornwell, David G.; Andreassen, Karin; Howell, John (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-02)
      Marine-based ice streams are responsible for a significant proportion of the ice mass loss from the present-day Greenland Ice Sheet, East Antarctic Ice Sheet (EAIS) and West Antarctic Ice Sheet (WAIS) but the processes controlling their initiation, evolution and shutdown remain elusive, hindering our understanding of how existing ice masses will respond to predicted future warming. The exposed beds ...
    • Multiple sulphur isotope records tracking basinal and global processes in the 1.98 Ga Zaonega Formation, NW Russia 

      Paiste, Kärt; Lepland, Aivo; Zerkle, A.L.; Kirsimäe, Kalle; Izon, G.; Patel, N.K.; McLean, F.; Kreitsmann, T.; Mänd, Kaarel; Bui, T.H.; Romashkin, Alexander E.; Rychanchik, Dimitry V.; Prave, Anthony R (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-19)
      The exceptionally organic-rich rocks of the 1.98 Ga Zaonega Formation deposited in the Onega Basin, NW Russia, have refined our understanding of Earth System evolution during the Paleoproterozoic rise in atmospheric oxygen. These rocks were formed in vent- or seep influenced settings contemporaneous with voluminous mafic volcanism and contain strongly <sup>13</sup>C-depleted organic matter. ...