Viser treff 289-308 av 711

    • 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 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 dedolomitisation of carbonate rocks of the Paleoproterozoic Zaonega Formation, NW Russia — Implications for the preservation of primary C isotope signals 

      Kreitsmann, Timmu; Külaviir, Marian; Lepland, Aivo; Paiste, Kärt; Paiste, Päärn; Prave, Anthony R.; Sepp, Holar; Romashkin, Alexander E; Rychanchik, Dmitry V.; Kirsimäe, Kalle (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-03)
      The Paleoproterozoic Zaonega Formation in Karelia, NW Russia, has played a key role in understanding the environmental conditions postdating the Great Oxidation and Lomagundi-Jatuli Events. Its carbonate- and organic-rich rocks (shungite) define the postulated Shunga Event representing an accumulation of very organic-rich sediments at c. 2 Ga and are central in ideas about changing ocean-atmosphere ...
    • Ice-sheet melt drove methane emissions in the Arctic during the last two interglacials 

      Dessandier, Pierre-Antoine; Knies, Jochen; Plaza-Faverola, Andreia; Labrousse, C.; Renoult, M.; Panieri, Giuliana (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-22)
      Circum-Arctic glacial ice is melting in an unprecedented mode, and release of currently trapped geological methane may act as a positive feedback on ice-sheet retreat during global warming. Evidence for methane release during the penultimate (Eemian, ca. 125 ka) interglacial, a period with less glacial sea ice and higher temperatures than today, is currently absent. Here, we argue that based on ...
    • Ice-sheet-driven methane storage and release in the Arctic 

      Portnov, Aleksei D; Vadakkepuliyambatta, Sunil; Mienert, Jurgen; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-07)
      It is established that late-twentieth and twenty-first century ocean warming has forced dissociation of gas hydrates with concomitant seabed methane release. However, recent dating of methane expulsion sites suggests that gas release has been ongoing over many millennia. Here we synthesize observations of B1,900 fluid escape features—pockmarks and active gas flares—across a previously glaciated ...
    • Ice-stream dynamics of the SW Barents Sea revealed by high-resolution 3D seismic imaging of glacial deposits in the Hoop area 

      Bellwald, Benjamin; Planke, Sverre; Piasecka, Emilia Daria; Matar, M.A.; Andreassen, Karin (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-07)
      Recent developments in seismic acquisition systems and seismic data visualization have contributed to improve the imaging of seismic geomorphologies over a broad range of topics. This study focuses on a new high-resolution P-Cable 3D seismic cube located in the Hoop area in the SW Barents Sea. The scientific motivations of the study are (1) to document glacial landforms on a meter-scale, (2) to study ...
    • Icelandic permafrost dynamics since the Last Glacial Maximum – model results and geomorphological implications 

      Etzelmüller, Bernd; Patton, Henry; Schomacker, Anders; Czekirda, Justyna; Girod, Luc; Hubbard, Alun Lloyd; Lilleøren, Karianne Staalesen; Westermann, Sebastian (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-14)
      Iceland’s periglacial realm is one of the most dynamic on the planet, with active geomorphologicalprocesses and high weathering rates of young bedrock resulting in high sediment yields and ongoingmass movement. Permafrost is discontinuous in Iceland’s highlands and mountains over c. 800 m a.s.l,and sporadic in palsa mires in the central highlands. During the late Pleistocene and Holocene, ...
    • Ice‐margin retreat and grounding‐zone dynamics during initial deglaciation of the Storfjordrenna Ice Stream, western Barents Sea 

      Shackleton, Calvin; Winsborrow, Monica; Andreassen, Karin; Lucchi, Renata Giulia; Bjarnadóttir, Lilja Rún (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-11)
      Processes occurring at the grounding zone of marine terminating ice streams are crucial to marginal stability, influencing ice discharge over the grounding‐line, and thereby regulating ice‐sheet mass balance. We present new marine geophysical data sets over a ~30×40 km area from a former ice‐stream grounding zone in Storfjordrenna, a large cross‐shelf trough in the western Barents Sea, south of ...
    • Ice‐rafting patterns on the western Svalbard slope 74–0 ka: interplay between ice‐sheet activity, climate and ocean circulation 

      Jessen, Simon Pind; Rasmussen, Tine Lander (Journal article; Tidsskriftartikkel, 2018-11-14)
      The distribution of ice‐rafted detritus (IRD) is studied in three cores from the western Svalbard slope (1130–1880 m water depth, 76–78°N) covering the period 74–0 ka. The aim was to provide new insight into the dynamics of the Svalbard–Barents Sea Ice Sheet during Marine Isotope Stages (MIS) 4–1 to get a better understanding of ice‐sheet interactions with changes in ocean circulation and climate ...
    • Identifying global vs. basinal controls on Paleoproterozoic organic carbon and sulfur isotope records 

      Paiste, Kärt; Lepland, Aivo; Zerkle, Aubrey L.; Kirsimae, Kalle; Kreitsmann, Timmu; Mänd, Kaarel; Romashkin, Alexander E.; Rychanchik, Dimitry V.; Prave, Anthony R (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-03)
      Paleoproterozoic sedimentary successions are important archives of the redox evolution of Earth’s atmosphere and oceans. Efforts to unravel the dynamics of our planet’s early oxygenation from this archive rely on various geochemical proxies, including stable carbon and sulfur isotopes. However, ancient metasedimentary rocks often experienced early- and late-stage (bio)geochemical processes making ...
    • Identifying past petroleum exploration related drill cutting releases and influences on the marine environment and benthic foraminiferal communities, Goliat Field, SW Barents Sea, Norway 

      Sørensen, Steffen Aagaard; Junttila, Juho; Dijkstra, Noortje (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-01)
      The present multiproxy investigation of marine sediment cores aims at: 1) Identifying dispersion of petroleum exploration related drill cutting releases within the Goliat Field, Barents Sea in 2006/07 and 2) Assessing past and present influence of drill cuttings on the marine environment. The cores were recovered 5, 30, 60, 125 and 250 m from the drill site in the eastward downstream direction.<p> ...
    • Image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern Barents Sea 

      Sen, Arunima; Chitkara, Chestaa; Hong, Wei-Li; Lepland, Aivo; Cochrane, Sabine; Di Primio, Rolando; Brunstad, Harald (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-08)
      <p><i>Background - </i>High primary productivity in the midst of high toxicity defines hydrocarbon seeps; this feature usually results in significantly higher biomass, but in lower diversity communities at seeps rather than in the surrounding non-seep benthos. Qualitative estimates indicate that this dichotomy does not necessarily hold true in high latitude regions with respect to megafauna. Instead, ...
    • Impact of Arctic shelf summer stratification on Holocene climate variability 

      Thibodeau, Benoit; Bauch, Henning A.; Knies, Jochen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-21)
      Understanding the dynamic of freshwater and sea-ice export from the Arctic is crucial to better comprehend the potential near-future climate change consequences. Here, we report nitrogen isotope data of a core from the Laptev Sea to shed light on the impact of the Holocene Siberian transgression on the summer stratification of the Laptev Sea. Our data suggest that the oceanographic setting was ...
    • Impact of drill cutting releases on benthic foraminifera at three exploration wells drilled between 1992 and 2012 in the SW Barents Sea, Norway 

      Dijkstra, Noortje; Junttila, Juho; Aagaard-Sørensen, Steffen (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-04)
      The aim of this study is to identify the environmental impact of drill cuttings (DC) released around three wells drilled in 1992, 2000 and 2012 in the SW Barents Sea. Foraminiferal assemblages are studied in cores taken along transects <250 m from wells. Well E-1992 shows no impact of DC on foraminifera indicating that low amounts of released DC limit environmental impact. Impact at wells G-2000 and ...
    • Impact of Gas Saturation and Gas Column Height at the Base of the Gas Hydrate Stability Zone on Fracturing and Seepage at Vestnesa Ridge, West-Svalbard Margin 

      Ramachandran, Hariharan; Plaza-Faverola, Andreia; Daigle, Hugh (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-26)
      The Vestnesa Ridge, located off the west Svalbard margin, is a >60 km long ridge consisting of fine-grained sediments that host a deep-marine gas hydrate and associated seepage system. Geological and geophysical observations indicate the predominance of vertical fluid expulsion through fractures with pockmarks expressed on the seafloor along the entire ridge. However, despite the apparent evidence ...
    • Impact of natural (waves and currents) and anthropogenic (trawl) resuspension on the export of particulate matter to the open ocean: Application to the Gulf of Lion (NW Mediterranean) 

      Ferré, Bénédicte; Durrieu de Madron, X.; Estournel, C.; Ulses, G.; Le Corre, G. (Journal article; Tidsskriftartikkel; Peer reviewed, 2008-02-17)
      <p>Modern sediment deposits on continental margins form a vast reservoir of particulate matter that is regularly affected by resuspension processes. Resuspension by bottom trawling on shelves with strong fishing activity can modify the scale of natural disturbance by waves and currents. Recent field data show that the impact of bottom trawls on fine sediment resuspension per unit surface is comparable ...