Now showing items 243-262 of 328

    • Rapid Surface Lowering of Benito Glacier, Northern Patagonian Icefield 

      Ryan, Jonathan C.; Sessions, Martin; Wilson, Ryan; Wündrich, Olaf; Hubbard, Alun L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-01)
      The Patagonian Icefields, which straddle the Andes below 46°S, are two of the most sensitive ice masses on Earth to climate change. However, recent mass loss from the icefields along with its spatial and temporal variability is not well-constrained. Here we determine surface elevation changes of Benito Glacier, a 163 km2 outlet glacier draining the western flank of the North Patagonian Icefield, ...
    • Re-evaluation and extension of the Marine Isotope Stage 5 tephrostratigraphy of the Faroe Islands region: The cryptotephra record 

      Abbott, Peter M.; Austin, William E.N.; Davies, Siwan M.; Pearce, Nicholas John Geoffrey; Rasmussen, Tine Lander; Wastegård, Stefan; Brendryen, Jo (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Reconstructing the retreat dynamics of the Bjørnøyrenna Ice Stream based on new 3D seismic data from the central Barents Sea 

      Piasecka, Emilia Daria; Winsborrow, Monica; Andreassen, Karin; Stokes, Chris R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-01)
      The stability of contemporary ice sheets is influenced by the discharge from ice streams - corridors of fast-flowing ice bounded by ice flowing an order of magnitude slower. Reconstructions of palaeo-ice stream dynamics contribute to our understanding of ice stream sensitivity to the ocean-climate system and can aid in the numerical modelling and prediction of future changes in contemporary ice ...
    • Reconstruction of Atlantic Water variability during the Holocene in the western Barents Sea 

      Groot, Diane; Sørensen, Steffen Aagaard; Husum, Katrine (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-01-10)
      The gravity core JM09-KA11-GC from 345m water depth on the western Barents Sea margin was investigated for down-core distribution patterns of benthic Foraminifera, stable isotopes, and sedimentological parameters in order to reconstruct the flow of Atlantic water during the Holocene. The core site is located below the Atlantic water masses flowing into the Arctic Ocean and close to the Arctic front. ...
    • Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols 

      Ezat, Mohamed; Rasmussen, Tine Lander; Groeneveld, Jeroen (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-08-20)
      The shallow subsurface hydrography in the southern Norwegian Sea during the past 135,000 years was investigated using parallel measurements of Mg/Ca and δ18O in shells of the planktic foraminiferal species Neogloboquadrina pachyderma. Two cleaning methods were applied prior to Mg/Ca analysis, “Mg cleaning” and “full cleaning” methods. Different results were obtained, which are most likely due to a ...
    • Reconstruction of ice sheet retreat after the Last Glacial maximum in Storfjorden, southern Svalbard 

      Nielsen, Tove; Rasmussen, Tine Lander (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-15)
      Storfjorden is a large north-south trending sound located in the southern part of Svalbard in the northwestern Barents Sea. Presently, several glaciers drain into the northern and western part of Storfjorden. Our study area covers the southern part of the sound, which is divided by a north-south striking basement ridge (the ‘Mid-ridge’) into a narrow western trough (‘Little-Storfjorden’) and a broader ...
    • Redox-dependent niche differentiation provides evidence for multiple bacterial sources of glycerol tetraether lipids in lakes 

      Weber, Yuki; Sinninghe Damsté, Jaap S.; Zopfi, Jakob; De Jonge, Cindy; Gilli, Adrian; Schubert, Carsten J.; Lepori, Fabio; Lehmann, Moritz F.; Niemann, Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-23)
      Terrestrial paleoclimate archives such as lake sediments are essential for our understanding of the continental climate system and for the modeling of future climate scenarios. However, quantitative proxies for the determination of paleotemperatures are sparse. The relative abundances of certain bacterial lipids, i.e., branched glycerol dialkyl glycerol tetraethers (brGDGTs), respond to changes in ...
    • Reduced methane seepage from Arctic sediments during cold bottom-water conditions 

      Ferré, Benedicte; Jansson, Pär; Moser, Manuel; Serov, Pavel; Portnov, Aleksei D; Graves, Carolyn; Panieri, Giuliana; Gründger, Friederike; Berndt, Christian; Lehmann, Moritz F.; Niemann, Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-13)
      Large amounts of methane are trapped within gas hydrate in subseabed sediments in the Arctic Ocean, and bottom-water warming may induce the release of methane from the seafloor. Yet the effect of seasonal temperature variations on methane seepage activity remains unknown as surveys in Arctic seas are conducted mainly in summer. Here we compare the activity of cold seeps along the gas hydrate stability ...
    • A refined late-Cryogenian – Ediacaran Earth history of South China: phosphorous-rich marbles of the Dabie and Sulu orogens 

      Prave, Anthony R; Meng, F.; Lepland, Aivo; Kirsimäe, Kalle; Kreitsmann, Timmu; Jiang, C.Z. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-02)
      The late-Cryogenian – Ediacaran geological framework for South China is constructed principally from sedimentary successions preserved in the central and western regions of the Yangtze Block. New stratigraphic and carbonate-carbon isotope data allow us to extend that framework into the exhumed HP-UHP subduction complexes of the eastern Dabie and Sulu orogens that separate the South and North China ...
    • Relating 3D surface displacement from satellite- and ground-based InSAR to structures and geomorphology of the Jettan rockslide, northern Norway 

      Eriksen, Harald Øverli; Bergh, Steffen G; Larsen, Yngvar; Skrede, Ingrid; Kristensen, Lene; Lauknes, Tom Rune; Blikra, Lars Harald; Kierulf, Halfdan Pascal (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-13)
      This study combines remote sensing data from ground- and satellite-based radar to calculate 3D displacement vectors for the Jettan rockslide, Troms, northern Norway. Using 3D displacement vectors, aspect data and strain rates in conjunction with structure (foliation, faults, fractures), geomorphological elements (ridges, scarps, terraces, depressions), topography and borehole data, we identify zones ...
    • 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 ...
    • Removal of methane through hydrological, microbial, and geochemical processes in the shallow sediments of pockmarks along eastern Vestnesa Ridge (Svalbard) 

      Hong, Wei-Li; Sauer, Simone; Panieri, Giuliana; Ambrose, William; James, Rachel; Plaza-Faverola, Andreia; Schneider, Andrea (Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
      The recent discovery of methane seeps in the Arctic region requires a better understanding of the fate of methane in marine sediments if we are to understand the contributions of methane to Arctic ecosystems and climate change. To further this goal, we analyze pore water data from five pockmarks along eastern Vestnesa Ridge, a sediment drift northwest of Svalbard, to quantify the consumption ...
    • Repeatability of high-resolution 3D seismic data 

      Waage, Malin; Bünz, Stefan; Landrø, Martin; Plaza-Faverola, Andreia; Waghorn, Kate Alyse (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-21)
      High-resolution 4D (HR4D) seismic data have the potential for improving the current state-of-the-art in detecting shallow (≤500−1000  m below seafloor) subsurface changes on a very fine scale (approximately 3–6 m). Time-lapse seismic investigations commonly use conventional broadband seismic data, considered low to moderate resolution in our context. We have developed the first comprehensive time ...
    • Reply to 'Challenges with dating weathering products to unravel ancient landscapes' 

      Fredin, Ola; Viola, Giulio; Zwingmann, Horst; Sørlie, Ronald; Brönner, Marco; Lie, Jan-Erik; Grandal, Else Margrethe; Müller, Axel; Margreth, Annina; Vogt, Christoph; Knies, Jochen (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-15)
      <i>Introduction</i>: As the title of the correspondence by Fossen et al.1 suggests, determining the age of landscape elements of the Earth surface is difficult. We thus welcome the opportunity to clarify our arguments on the contentious themes touched upon by Fredin et al.2 The age of landscapes has been a recurring research topic for the last century. Often, landscape ages can be deduced indirectly ...
    • Resolving the internal and basal geometry of ice masses using imaging phase-sensitive radar 

      Young, Tun Jan; Schroeder, Dustin M.; Christoffersen, Poul; Lok, Lai B.; Nicholls, Keith W.; Brennan, Paul V.; Doyle, Samuel H.; Hubbard, Bryn; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-19)
      The phase-sensitive radio-echo sounder (pRES) is a powerful new instrument that can measure the depth of internal layers and the glacier bed to millimetre accuracy. We use a stationary 16-antenna pRES array on Store Glacier in West Greenland to measure the three-dimensional orientation of dipping internal reflectors, extending the capabilities of pRES beyond conventional depth sounding. This novel ...
    • Retreat patterns and dynamics of the Sentralbankrenna glacial system, central Barents Sea 

      Esteves, Mariana da Silveira Ramos; Bjarnadóttir, Lilja Rún; Winsborrow, Monica; Shackleton, Calvin; Andreassen, Karin (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-26)
      The Barents Sea Ice Sheet (BSIS) is a good palaeo-analogue for the present day West Antarctic Ice Sheet. Both were marine-based ice sheets, particularly vulnerable to ocean warming and sea-level rise. Understanding the BSIS ice dynamics and patterns of retreat since the Last Glacial Maximum (LGM) is useful in developing our knowledge of spatial and temporal variations during marine-based ice sheet ...
    • Reviewing the Cenozoic Net Erosion of the Barents Sea Shelf 

      Lasabuda, Amando Putra Ersaid; Laberg, Jan Sverre; Knutsen, Stig-Morten; Rydningen, Tom Arne (Conference object; Konferansebidrag, 2019-01)
    • Rheological Weakening of Olivine + Orthopyroxene Aggregates Due To Phase Mixing: Part 2. Microstructural Development 

      Tasaka, Miki; Zimmerman, Mark E; Kohlstedt, David L.; Stünitz, Holger; Heilbronner, Renée (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-08)
      To understand the processes involved in phase mixing during deformation and the resulting changes in rheological behavior, we conducted torsion experiments on samples of iron‐rich olivine plus orthopyroxene. The experiments were conducted at a temperature, T, of 1200°C and a confining pressure, P, of 300 MPa using a gas‐medium deformation apparatus. Samples composed of olivine plus 26% orthopyroxene ...
    • Rock glaciers in central Patagonia 

      Selley, Heather; Harrison, Stephan; Glasser, Neil; Wündrich, Olaf; Colson, Daniel; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-22)
      Active rock glaciers are ice and debris-cored landforms common in cold arid mountains. They have not been widely described in the Patagonian Andes of southern South America and here we provide the first rock glacier inventory for the Jeinimeni region to the east of the contemporary North Patagonian Icefield. Detailed analysis of available satellite imagery and fieldwork demonstrates the presence of ...
    • The Role of Magmatic and Hydrothermal Fluids in the Formation of the Sasa Pb-Zn-Ag Skarn Deposit, Republic of Macedonia 

      Strmic Palinkas, Sabina; Peltekovski, Zlatko; Tasev, Goran; Serafimovski, Todor; Šmajgl, Danijela; Rajic, Kristijan; Spangenberg, Jorge; Neufeld, Kai; Palinkaš, Ladislav A. (Journal article; Peer reviewed, 2018-11-29)
      The Sasa Pb-Zn-Ag deposit belongs to the group of distal base metal skarn deposits. The deposit is located within the Serbo-Macedonian massif, a metamorphosed crystalline terrain of Precambrian to Paleozoic age. The mineralization, hosted by Paleozoic marbles, shows a strong lithological control. It is spatially and temporally associated with the calc-alkaline to shoshonitic post-collisional magmatism ...