Viser treff 245-264 av 711

    • 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 ...
    • Geomorphology and surficial geology of the Femmilsjøen area, northern Spitsbergen 

      Allaart, Lis; Schomacker, Anders; Håkansson, Lena; Farnsworth, Wesley R.; Brynjólfsson, Skafti; Grumstad, Andreas; Kjellman, Sofia Elisabeth (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-09)
      Climate change is amplified in the Arctic, and establishing baseline data for its current character is important. Here we present a map of the geomorphology of the Femmilsjøen area, Spitsbergen, northern Svalbard. The regional physiography is characterised by a low-relief, high elevation mountain plateau, its high-relief steep slopes, and low-relief coastal lowlands. The results indicate that glaciers ...
    • 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, ...
    • Glacial and environmental changes in northern Svalbard over the last 16.3 ka inferred from neodymium isotopes 

      Jang, Kwangchul; Ahn, Youngkyu; Joe, Young Jin; Braun, Carmen; Joo, Young Ji; Kim, Jung-Hyun; Bayon, Germain; Forwick, Matthias; Vogt, Christoph; Nam, Seung-Il (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-05)
      The reconstruction of past ice sheet extents and dynamics in polar regions is essential for understanding the global climate system and obtaining more reliable predictions of future climate change. Here, we present a multi-proxy dataset integrating the Nd isotopic compositions (εNd) of paired detrital and authigenic Fe oxide fractions, grain size distributions, organic geochemistry, and mineral ...
    • Glacial history and depositional environments in little Storfjorden and Hambergbukta of Arctic Svalbard since the younger dryas 

      Joe, Young Jin; Jang, Kwangchul; Forwick, Matthias; Laberg, Jan Sverre; Kong, Gee Soo; Kang, Moo-Hee; Yoon, Seok-Hoon; Nam, Seung-Il (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-21)
      Geophysical and lithological data provide crucial information for the understanding of glacial history in Arctic Svalbard. In this study, we reconstructed the glacier-induced depositional environments of Little Storfjorden and its tributary, Hambergbukta, over the last 13 ka to better understand the glacial history of southeastern Svalbard. The combined uses of swath-bathymetry, high-resolution ...
    • Glacial history of the Åsgardfonna Ice Cap, NE Spitsbergen, since the last glaciation 

      Allaart, Lis; Schomacker, Anders; Larsen, Nicolaj K.; Nørmark, Egon; Rydningen, Tom Arne; Farnsworth, Wesley R.; Retelle, Michael J.; Brynjólfsson, Skafti; Forwick, Matthias; Kjellman, Sofia Elisabeth (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-30)
      The response of glaciers and ice caps to past climate change provides important insight into how they will react to ongoing and future global warming. In Svalbard, the Holocene glacial history has been studied for many cirque and valley glaciers. However, little is known about how the larger ice caps in Svalbard responded to Late Glacial and Holocene climate changes. Here we use lake sediment cores ...
    • Glacial isostatic adjustment associated with the Barents Sea ice sheet: A modelling inter-comparison 

      Auriac, Amandine; Whitehouse, P.L.; Bentley, M.J.; Patton, Henry; Lloyd, J.M.; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-01)
      The 3D geometrical evolution of the Barents Sea Ice Sheet (BSIS), particularly during its late-glacial retreat phase, remains largely ambiguous due to the paucity of direct marine- and terrestrial-based evidence constraining its horizontal and vertical extent and chronology. One way of validating the numerous BSIS reconstructions previously proposed is to collate and apply them under a wide range ...
    • Glacial-interglacial sedimentation control on gas seepage exemplified by Vestnesa Ridge off NW Svalbard margin 

      Rasmussen, Tine Lander; Nielsen, Tove (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-08)
      Vestnesa Ridge is built-up of thick contourites mainly deposited during the last ∼5 million years. Methane leaks from deep gas reservoirs creating pockmarks on its crest, and which have been the focus of numerous studies. Sedimentation patterns in relation to the pronounced changes in oceanography and climate of the last glacial-interglacial cycles and its possible impact of seepage of gas have ...
    • Glacially Induced Stress Across the Arctic From the Eemian Interglacial to the Present—Implications for Faulting and Methane Seepage 

      Vachon, Remi Elie Celestin; Schmidt, P.; Lund, Bjorn; Plaza-Faverola, Andreia; Patton, Henry; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-28)
      Strong compressive and shear stresses generated by glacial loading and unloading have a direct impact on near-surface geological processes. Glacial stresses are constantly evolving, creating stress perturbations in the lithosphere that extend significant distances away from the ice. In the Arctic, periodic methane seepage and faulting have been recurrently associated with glacial cycles. However, ...
    • Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet 

      Cook, Joseph M.; Tedstone, Andrew J.; Williamson, Christopher; McCutcheon, Jenine; Hodson, Andrew J.; Dayal, Archana; Skiles, McKenzie; Hofer, Stefan; Bryant, Robert; McAree, Owen; McGonigle, Andrew; Ryan, Jonathan; Anesio, Alexandre M.; Irvine-Fynn, Tristram D.L.; Hubbard, Alun Lloyd; Hanna, Edward; Flanner, Mark; Mayanna, Sathish; Benning, Liane G.; van As, Dirk; Yallop, Marian; McQuaid, James B.; Gribbin, Thomas; Tranter, Martyn (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-29)
      Melting of the Greenland Ice Sheet (GrIS) is the largest single contributor to eustatic sea level and is amplified by the growth of pigmented algae on the ice surface, which increases solar radiation absorption. This biological albedo-reducing effect and its impact upon sea level rise has not previously been quantified. Here, we combine field spectroscopy with a radiative-transfer model, supervised ...
    • Glacier response to the Little Ice Age during the Neoglacial cooling in Greenland 

      Kjær, Kurt H.; Bjørk, Anders A.; Kjeldsen, Kristian K.; Hansen, Eric S.; Andresen, Camilla S.; Siggaard-Andersen, Marie-Louise; Khan, Shfaqat Abbas; Søndergaard, Anne Sofie; Colgan, William; Schomacker, Anders; Woodroffe, Sarah; Funder, Svend; Rouillard, Alexandra; Jensen, Jens Fog; Larsen, Nicolaj K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-04)
      In the Northern Hemisphere, an insolation driven Early to Middle Holocene Thermal Maximum was followed by a Neoglacial cooling that culminated during the Little Ice Age (LIA). Here, we review the glacier response to this Neoglacial cooling in Greenland. Changes in the ice margins of outlet glaciers from the Greenland Ice Sheet as well as local glaciers and ice caps are synthesized Greenland-wide. ...
    • Glacigenic landforms and sediments in Store Koldewey Trough, NE Greenland – preliminary results 

      Olsen, Ingrid Leirvik; Forwick, Matthias; Laberg, Jan Sverre; Rydningen, Tom Arne; Husum, Katrine (Conference object; Konferansebidrag, 2018-04)
      The glaciation history of NE Greenland remains poorly constrained, resulting in conceptual and uncertain reconstructions of the configuration of the Greenland Ice Sheet during the Last Glacial Maximum (c. 24-19 ka BP), as well as the timing and the dynamics of the deglaciation. New studies suggests that the ice sheet in NE Greenland probably was more dynamic than previously thought, extending all ...
    • Glacigenic sedimentation pulses triggered postglacial gas hydrate dissociation 

      Karstens, Jens; Haflidason, Haflidi; Becker, Lukas W.M.; Berndt, Christian; Rüpke, Lars; Planke, Sverre; Liebetrau, Volker; Schmidt, Markus; Mienert, Jürgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-02-12)
      Large amounts of methane are stored in continental margins as gas hydrates. They are stable under high pressure and low, but react sensitively to environmental changes. Bottom water temperature and sea level changes were considered as main contributors to gas hydrate dynamics after the last glaciation. However, here we show with numerical simulations that pulses of increased sedimentation dominantly ...
    • Global temperature calibration of the Long chain Diol Index in marine surface sediments 

      de Bar, Marijke W.; Weiss, Gabriella; Yildiz, Caglar; Rampen, Sebastiaan W.; Lattaud, Julie; Bale, Nicole J.; Mienis, Furu; Brummer, Geert-Jan A.; Schulz, Hartmut; Rush, Darci; Kim, Jung-Hyun; Donner, Barbara; Knies, Jochen; Lückge, Andreas; Stuut, Jan-Berend W.; Sinninghe Damsté, Jaap S.; Schouten, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-07)
      The Long chain Diol Index (LDI) is a relatively new organic geochemical proxy for sea surface temperature (SST), based on the abundance of the C<sub>30</sub> 1,15-diol relative to the summed abundance of the C<sub>28</sub> 1,13-, C<sub>30</sub> 1,13- and C<sub>30</sub> 1,15-diols. Here we substantially extend and re-evaluate the initial core top calibration by combining the original dataset with 172 ...
    • Greenland ice sheet climate disequilibrium and committed sea-level rise 

      Box, Jason E.; Hubbard, Alun Lloyd; Bahr, David B.; Colgan, William T.; Fettweis, Xavier; Mankoff, Kenneth D.; Wehrlé, Adrien; Noel, Brice; Van Den Broeke, Michiel R.; Wouters, Bert; Bjørk, Anders A.; Fausto, Robert S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-29)
      Ice loss from the Greenland ice sheet is one of the largest sources of contemporary sea-level rise (SLR). While process-based models place timescales on Greenland’s deglaciation, their confidence is obscured by model shortcomings including imprecise atmospheric and oceanic couplings. Here, we present a complementary approach resolving ice sheet disequilibrium with climate constrained by satellite-derived ...
    • Greenland Ice Sheet surface melt amplified by snowline migration and bare ice exposure 

      Ryan, J.C.; Smith, L.C.; Van As, D.; Cooley, S.W.; Cooper, M.G.; Pitcher, L.H.; Hubbard, A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-06)
      Greenland Ice Sheet mass loss has recently increased because of enhanced surface melt and runoff. Since melt is critically modulated by surface albedo, understanding the processes and feedbacks that alter albedo is a prerequisite for accurately forecasting mass loss. Using satellite imagery, we demonstrate the importance of Greenland’s seasonally fluctuating snowline, which reduces ice sheet albedo ...
    • Grounding line proximal sediment characteristics at a marine-based, late-stage ice stream margin 

      Rüther, Denise Christina; Winsborrow, Monica; Andreassen, Karin; Forwick, Matthias (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-12)
      Geomorphological evidence suggests that ice streams undergo frequent dynamic changes towards the end of their life cycles, but the associated sedimentary characteristics and processes remain poorly understood. Here, we present new sedimentological data from a Late Weichselian marine‐based ice stream in upper Bjørnøyrenna, northern Barents Sea, which experienced accelerated flow, intense calving of ...