Now showing items 378-397 of 989

    • Historical contingency impacts on community assembly and ecosystem function in chemosynthetic marine ecosystems 

      Kalenitchenko, Dimitri; Peru, Erwan; Galand, Pierre E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-07)
      Predicting ecosystem functioning requires an understanding of the mechanisms that drive microbial community assembly. Many studies have explored microbial diversity extensively and environmental factors are thought to be the principal drivers of community composition. Community assembly is, however, also influenced by past conditions that might affect present-day assemblages. Historical events, ...
    • The history and future trends of ocean warming-induced gas hydrate dissociation in the SW Barents Sea 

      Vadakkepuliyambatta, Sunil; Chand, Shyam; Bünz, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-01-13)
      The Barents Sea is a major part of the Arctic where the Gulf Stream mixes with the cold Arctic waters. Late Cenozoic uplift and glacial erosion have resulted in hydrocarbon leakage from reservoirs, evolution of fluid flow systems, shallow gas accumulations, and hydrate formation throughout the Barents Sea. Here we integrate seismic data observations of gas hydrate accumulations along with gas hydrate ...
    • Holocene atmospheric circulation in the central North Pacific: A new terrestrial diatom and d18O dataset from the Aleutian Islands 

      Bailey, Hannah L.; Kaufman, Darrell S.; Sloane, Hilary J.; Hubbard, Alun Lloyd; Henderson, Andrew C.G.; Leng, Melanie J.; Meyer, Hanno; Welker, Jeffrey M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-02)
      The North Pacific is a zone of cyclogenesis that modulates synoptic-scale atmospheric circulation, yet there is a paucity of instrumental and paleoclimate data to fully constrain its long-term state and variability. We present the first Holocene oxygen isotope record (δ<sup>18</sup>O<sub>diatom</sub>) from the Aleutian Islands, using siliceous diatoms preserved in Heart Lake on Adak Island (51.85° ...
    • Holocene climate variability in the Norwegian current and North Cape current inferred from benthic stable isotope records 

      Johannessen, Hilde B. (Master thesis; Mastergradsoppgave, 2006-06-14)
      The Malangenfjord, with its deep sill and good hydrological communication with the Norwegian Sea, has been the site for a high resolution paleoclimatic investigation. By using benthic foraminifera and stable isotopes from a marine sediment core, this study will reconstruct the changes in inflow of warm Atlantic Water at a high-latitude setting.<br><br> Radiocarbon dating has give ages between 8000 ...
    • Holocene development of subarctic permafrost peatlands in Finnmark, northern Norway 

      Kjellman, Sofia E.; Axelsson, Pia E.; Etzelmüller, Bernd; Westermann, Sebastian; Sannel, A. Britta K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-01)
      Subarctic permafrost peatlands are important soil organic carbon pools, and improved knowledge about peat properties and peatland sensitivity to past climate change is essential when predicting future response to a warmer climate and associated feedback mechanisms. In this study, Holocene peatland development and permafrost dynamics of four subarctic peat plateaus in Finnmark, northern Norway have ...
    • Holocene environmental changes in Dicksonfjorden, west Spitsbergen, Svalbard 

      Joo, Young Ji; Forwick, Matthias; Park, Kwangkyu; Joe, Youngjin; Son, Yeong Ju; Nam, Seung-Il (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-26)
      Multi-proxy analyses of two sediment cores from Dicksonfjorden were performed to reconstruct Holocene environmental conditions in this northern branch of Isfjorden, the largest fjord system in Svalbard. Factors affecting the depositional processes include shifts in sources of sediments, ice rafting and regional glacio-isostatic rebound. Sediments were derived from Palaeozoic siliciclastics ...
    • Holocene Glacial Dynamics of the Barentsøya ice cap, Svalbard 

      Leister, Juliane (Master thesis; Mastergradsoppgave, 2018-05-13)
      This study investigates the glacial dynamics of Barentsjøkulen, a small ice cap located on Barentsøya, Svalbard. In order to reconstruct Barentsjøkulen’s glacial history, three geomorphological maps of the glacier forefields of its main outlet glaciers, Besselsbreen, Duckwitzbreen and Freemanbreen, were created. The maps cover a total area of ca. 117 km2 and were generated based on swath bathymetric ...
    • Holocene precipitation seasonality in northern Svalbard: Influence of sea ice and regional ocean surface conditions 

      Kjellman, Sofia Elisabeth; Schomacker, Anders; Thomas, Elizabeth K.; Håkansson, Lena; Duboscq, Sandrine; Cluett, Allison; Farnsworth, Wesley R.; Allaart, Lis; Cowling, Owen; McKay, Nicholas P.; Brynjólfsson, Skafti; Ingólfsson, Ólafur (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-13)
      Arctic precipitation is predicted to increase in the coming century, due to a combination of enhanced northward atmospheric moisture transport and local surface evaporation from ice-free seas. However, large model uncertainties, limited long-term observations, and high spatiotemporal variability limit our understanding of these mechanisms, emphasizing the need for paleoclimate records of precipitation ...
    • Holocene relative sea-level changes and deglaciation chronology in Finnmark, northern Norway 

      Bennike, Ole; Romundset, Anders; Bondevik, Stein (Journal article; Tidsskriftartikkel, 2010-10)
      The outer coast of Finnmark in northern Norway is where the former Fennoscandian and Barents Sea ice sheets coalesced. This key area for isostatic modelling and deglaciation history of the ice sheets has abundant raised shorelines, but only a few existing radiocarbon dates relate to them. Here we present three Holocene sea-level curves based on radiocarbon ages from deposits in isolation basins ...
    • Holocene relative shore-level changes and development of the Ģipka lagoon in the western Gulf of Riga 

      Rosentau, Alar; Grudzinska, Ieva; Kalińska, Edyta; Alexanderson, Helena; Bērziņš, Valdis; Ceriņa, Aija; Kalniņa, Laimdota; Karušs, Jānis; Lamsters, Kristaps; Muru, Merle; Nartišs, Māris; Paparde, Līga; Hang, Tiit (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-13)
      Holocene relative shore-level changes and development of the G ipka palaeolagoon in the western Gulf of Riga are reconstructed using multiproxy analyses by combining litho-, biostratigraphical and chronological data with remote sensing and geophysical data. The results show the development of the G ipka basin from the Ancylus Lake/Initial Litorina Sea coastal zone (before c. 9.1 cal. ka BP) to ...
    • Holocene sedimentary environments in Smeerenburgfjorden, Spitsbergen 

      Velle, Julie Heggdal (Master thesis; Mastergradsoppgave, 2012-11-15)
      Multi-proxy analyses of six sediment cores (including lithostratigraphy, physical properties, granulometric analyses, and XRF scanning), and analyses of swath bathymetry and chirp data were integrated to elucidate the Holocene sedimentary processes and palaeoenvironments in Smeerenburgfjorden, northwest Spitsbergen. Three basins separated by two sills define the present-day large-scale bathymetry. ...
    • Holocene sub-centennial evolution of Atlantic water inflow and sea ice distribution in the western Barents Sea 

      Berben, Sarah; Husum, Katrine; Cabedo Sanz, Patricia; Belt, Simon T. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-01-23)
      A marine sediment core (JM09-KA11-GC) from the Kveithola Trough at the western Barents Sea margin has been investigated in order to reconstruct sub-surface temperatures and sea ice distribution at a sub-centennial resolution throughout the Holocene. The relationship between past variability of Atlantic water inflow and sea ice distribution has been established by measurement of planktic foraminifera, ...
    • Homogeneous glacial landscapes can have high local variability of strontium isotope signatures: Implications for prehistoric migration studies 

      Thomsen, Erik; Andreasen, Rasmus; Rasmussen, Tine Lander (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-15)
      Increasingly, strontium (Sr) isotopes are used to distinguish locals and migrants in prehistoric studies, by measuring <sup>87</sup>Sr/<sup>86</sup>Sr in human remains and comparing these values to the distribution of the bioavailable <sup>87</sup>Sr/<sup>86</sup>Sr in the study area, often in surface water. However, it has recently been shown that agricultural lime can have a substantial impact on ...
    • Hot Vents Beneath an Icy Ocean: The Aurora Vent Field, Gakkel Ridge, Revealed 

      Ramirez-Llodra, Eva; Argentino, Claudio; Baker, Maria; Boetius, Antje; Costa, Carolina; Dahle, Håkon; Denny, Emily Maria; Dessandier, Pierre-Antoine; Eilertsen, Mari Heggernes; Ferré, Benedicte; German, Cristopher R.; Hand, Kevin; Hilário, Ana; Hislop, Lawrence; Jamieson, John W.; Kalnitchenko, Dimitri; Mall, Achim; Panieri, Giuliana; Purser, Autun; Ramalho, Sofia P.; Reeves, Eoghan P.; Rolley, Leigthon; Pereira, Samuel I.; Ribeiro, Pedro A.; Sert, Muhammed Fatih; Steen, Ida H.; Stetzler, Marie; Stokke, Runar; Victorero, Lissette; Vulcano, Francesca; Vågenes, Stig; Waghorn, Kate Alyse; Buenz, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-28)
      Evidence of hydrothermal venting on the ultra-slow spreading Gakkel Ridge in the Central Arctic Ocean has been available since 2001, with first visual evidence of black smokers on the Aurora Vent Field obtained in 2014. But it was not until 2021 that the first ever remotely operated vehicle (ROV) dives to hydrothermal vents under permanent ice cover in the Arctic were conducted, enabling the ...
    • How Academics and the Public Experienced Immersive Virtual Reality for Geo-Education 

      Bonali, Fabio L.; Russo, Elena; Vitello, Fabio; Antoniou, Varvara; Marchese, Fabio; Fallati, Luca; Bracchi, Valentina; Corti, Noemi; Savini, Alessandra; Whitworth, Malcom; Drymoni, Kyriaki; Mariotto, Federico Pasquaré; Nomikou, Paraskevi V.; Sciacca, Eva; Bressan, Sofia; Falsaperla, Susanna; Reitano, Danilo; van Wyk de Vries, Benjamin; Krokos, Mel; Panieri, Giuliana; Stiller-Reeve, Matthew Alexander; Vizzari, Giuseppe; Becciani, Ugo; Tibaldi, Alessandro (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-24)
      Immersive virtual reality can potentially open up interesting geological sites to students, academics and others who may not have had the opportunity to visit such sites previously. We study how users perceive the usefulness of an immersive virtual reality approach applied to Earth Sciences teaching and communication. During nine immersive virtual reality-based events held in 2018 and 2019 in ...
    • How is the carbon and oxygen isotope composition of foraminiferal tests influenced by methane seepage? 

      Bruvik, Kine Liland (Master thesis; Mastergradsoppgave, 2019-06-05)
      The focus of this thesis is how methane seepage influences foraminifera l tests. Specifically, How how carbon and oxygen isotopes in planktic foraminifera tests are influenced by methane seepage. The study area is Vestnesa Ridge were four gravity cores were collected during a CAGE cruise in 2013. The cores were taken both from the southern side, where flares has have been recorded, and from the ...
    • How robust are in situ observations for validating satellite-derived albedo over the dark zone of the Greenland Ice Sheet? 

      Ryan, J.C.; Hubbard, Alun Lloyd; Irvine-Fynn, T.; Doyle, S.H.; Cook, J.M.; Stibal, Marek; Box, J.E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-17)
      Calibration and validation of satellite‐derived ice sheet albedo data require high‐quality, in situ measurements commonly acquired by up and down facing pyranometers mounted on automated weather stations (AWS). However, direct comparison between ground and satellite‐derived albedo can only be justified when the measured surface is homogeneous at the length‐scale of both satellite pixel and in situ ...
    • Hydrate occurrence in Europe: A review of available evidence 

      Minshull, Timothy A.; Marin-Moreno, Hector; Betlem, Peter; Bialas, Joerg; Bünz, Stefan; Burwicz, Ewa; Cameselle, Alejandra L.; Cifci, Gunay; Giustiniani, Michela; Hillman, Jess I.T.; Hölz, Sebastian; Hopper, John R.; Ion, Gabriel; Leon, Ricardo; Magalhaes, Vitor; Makovsky, Yizhaq; Mata, Maria-Pilar; Max, Michael D.; Nielsen, Tove; Okay, Seda; Ostrovsky, Ilia; O'Neil, Nick; Pinheiro, Luis M.; Plaza-Faverola, Andreia; Rey, Daniel; Roy, Srikumar; Schwalenberg, Katrin; Senger, Kim; Vadakkepuliyambatta, Sunil; Vasilev, Atanas; Vázquez, Juan-Tomás (Journal article; Tidsskriftartikkel, 2019-08-16)
      Large national programs in the United States and several Asian countries have defined and characterised their marine methane hydrate occurrences in some detail, but European hydrate occurrence has received less attention. The European Union-funded project “Marine gas hydrate – an indigenous resource of natural gas for Europe” (MIGRATE) aimed to determine the European potential inventory of exploitable ...
    • Hydrocarbon leakage driven by quaternary glaciations in the Barents Sea based on 2D basin and petroleum system modeling 

      Kishankov, Aleksei; Serov, Pavel; Bünz, Stefan; Patton, Henry Jared; Hubbard, Alun Lloyd; Mattingsdal, Rune; Vadakkepuliyambatta, Sunil; Andreassen, Karin Marie (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-25)
      The Barents Sea has experienced intense erosion throughout the Cenozoic due to uplift and repeated episodes of glaciation. This, in turn, has driven large pressure and temperature fluctuations in the sediment substrate along with rearrangement of thermogenic oil and gas accumulations. As a result, some hydrocarbon fields have relatively shallow depths, and natural gas release is widespread. This ...
    • Hydrothermal Cu-Zn mineralization at Vanna, West Troms Basement Complex: A geochemical analysis of Archean and Proterozoic rocks with focus on sulfide genesis 

      Monsen, Karina (Master thesis; Mastergradsoppgave, 2014-08-16)
      The hydrothermal Vannareid Cu-Zn mineralization is located on the island of Vanna, West Troms Basement Complex. It was discovered in 2008 and was subject of Store Norske Gull AS' exploration project in 2012. The mineralization is situated along the border between the Archean granitoid basement intruded by tholeiitic and calc-alkaline dykes, and the overlying Neoproterozoic metasedimentary rocks of ...