Viser treff 252-271 av 711

    • 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 ...
    • Groundwater springs formed during glacial retreat are a large source of methane in the high Arctic 

      Kleber, Gabreille E.; Hodson, Andrew; Magerl, Jasper Leonard; Mannerfelt, Erik Schytt; Bradbury, Harold J.; Zhu, Yizhu; Trimmer, Mark; Turchyn, Alexandra V. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-06)
      Permafrost and glaciers in the high Arctic form an impermeable ‘cryospheric cap’ that traps a large reservoir of subsurface methane, preventing it from reaching the atmosphere. Cryospheric vulnerability to climate warming is making releases of this methane possible. On Svalbard, where air temperatures are rising more than two times faster than the average for the Arctic, glaciers are retreating and ...
    • The Hambergfjellet Formation on Bjørnøya – sedimentary response to early Permian tectonics on the Stappen High 

      Grundvåg, Sten-Andreas; Strand, Mathias; Paulsen, Christian Oen; Simonsen, Bjørn; Røstad, Jostein; Mørk, Atle; Mørk, Mai Britt Engeness (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-14)
      On Bjørnøya, the exhumed crest of the Stappen High, the lower Permian (Cisuralian) Hambergfjellet Formation represents the only exposed part of the Bjarmeland Group carbonate platform, which occurs widely elsewhere in the subsurface of the Barents Shelf. A complex stratigraphic architecture has earlier been noted for the Hambergfjellet Formation and thickness estimates range from c. 50 to more than ...
    • Hammerfest Basin Composite Tectono-Sedimentary Element 

      Henriksen, Erik; Kvamme, L.; Rydningen, Tom Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-21)
      The Hammerfest Basin is an E -W trending graben located between the Loppa High and the Finnmark Platform in the southern part of the Norwegian Barents Sea. Mainly siliciclastic strata of Carboniferous to Cenozoic age cover the Caledonian basement and have a total estimated thickness of 5-8 km. The basin evolved through several tectonic phases: the Carboniferous rifting, Late Jurassic rifting, the ...
    • Handwritten letters and photo albums linking geoscientists with school classes 

      Stiller-Reeve, Mathew Alexander; Argentino, Claudio; Waghorn, Kate Alyse; Vadakkepuliyambatta, Sunil; Kalenitchenko, Dimitri; Panieri, Giuliana (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-14)
      Was something lost as society moved away from “traditional” media such as handwritten letters and photography and into the digital age? Some of the authors remember this age fondly, and we wanted to see if this fondness could be translated into a science dialogue project with school classes. We designed and carried out a communication process with four classes at different schools across Europe. ...
    • The Heliconoides Modified Dissolution Index-HMDI: Do methane seepage environments affect the preservation state of Heliconoides inflatus? 

      Beccari, Valentina; Almogi-Labin, Ahuva; Basso, Daniela; Panieri, Giuliana; Makovsky, Yizhaq; Neururer, Christoph; Hajdas, Irka; Spezzaferri, Silvia (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-24)
      Pteropods are holoplanktonic molluscs presently endangered because their fragile aragonitic shell is very sensitive to ocean acidification. The preservation of pteropods, and in particular of the mesopelagic Heliconoides (Limacina) inflatus, has been used to assess aragonite saturation state in Quaternary sediments (Limacina Dissolution Index, LDX) as an inferred proxy for climatic changes. Three ...
    • Heterogeneous REE + Y distribution in Early Paleozoic shelly phosphorites: Implications for enrichment mechanisms 

      Lumiste, Kaarel; Lang, Liisa; Paiste, Päärn; Lepland, Aivo; Kirsimäe, Kalle (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-27)
      Sedimentary phosphorites are important carriers of Rare Earth Elements and Yttrium (REE + Y). Primary biogenic and sedimentary apatite contain very low amounts of REE + Y and enrichment of these elements occurs during diagenesis. Although the influence of post-depositional processes on REE + Y concentrations in sedimentary phosphorites is well established, the processes controlling the degree of ...
    • HgCl2 addition to pore water samples from cold seeps can affect the geochemistry of dissolved inorganic carbon ([DIC], δ13CDIC) 

      Argentino, Claudio; Kalenitchenko, Dimitri; Lindgren, Johan Matteus; Panieri, Giuliana (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-03)
      The conventional use of mercuric chloride (HgCl<sub>2</sub>) as an antimicrobial agent in water samples for dissolved inorganic carbon (DIC) analysis poses health and environmental risks related to its handling and disposal. Even though there is an increasing interest in quantifying pore water DIC contribution to the ocean carbon cycle and deep-sea acidification, the paucity of comparative studies ...