Viser treff 440-459 av 698

    • OBS Data Analysis to Quantify Gas Hydrate and Free Gas in the South Shetland Margin (Antarctica) 

      Song, Sha; Tinivella, Umberta; Giustiniani, Michela; Singhroha, Sunny; Bünz, Stefan; Cassiani, Giorgio (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-25)
      The presence of a gas hydrate reservoir and free gas layer along the South Shetland margin (offshore Antarctic Peninsula) has been well documented in recent years. In order to better characterize gas hydrate reservoirs, with a particular focus on the quantification of gas hydrate and free gas and the petrophysical properties of the subsurface, we performed travel time inversion of ocean-bottom ...
    • Ocean temperature variability for the past 60 years on the Norwegian-Svalbard margin influences gas hydrate stability on human time scales 

      Ferré, Benedicte; Mienert, Jurgen; Feseker, Tomas (Journal article; Tidsskriftartikkel; Peer reviewed, 2012-10-23)
      The potential impact of future climate change on methane release from oceanic gas hydrates is the subject of much debate. We analyzed World Ocean Database quality controlled data on the Norwegian‐Svalbard continental margin from the past 60 years to evaluate the potential effect of ocean temperature variations on continental margin gas hydrate reservoirs. Bottom water temperatures in the Norwegian‐Svalbard ...
    • Offshore permafrost decay and massive seabed methane escape in water depths >20 m at the South Kara Sea shelf 

      Portnov, Alexey; Mienert, Jurgen; Cherkashov, Georgy; Rekant, Pavel; Semenov, Peter; Serov, Pavel; Vanshtein, Boris; Smith, Andrew James (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-07-14)
      Since the Last Glacial Maximum (~19 ka), coastal inundation from sea-level rise has been thawing thick subsea permafrost across the Arctic. Although subsea permafrost has been mapped on several Arctic continental shelves, permafrost distribution in the South Kara Sea and the extent to which it is acting as an impermeable seal to seabed methane escape remains poorly understood. Here we use >1300 km ...
    • On Palaeozoic-Mesozoic brittle normal faults along the SW Barents Sea margin: fault processes and implications for basement permeability and margin evolution 

      Indrevær, Kjetil; Stunitz, Holger; Bergh, Steffen G (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • On the causes of Arctic sea ice in the warm Early Pliocene 

      Clotten, Caroline; Stein, Rüdiger; Fahl, Kirsten; Schreck, Michael; Risebrobakken, Bjørg; De Schepper, Stijn (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-30)
      Scattered and indirect evidence suggests that sea ice occurred as far south as the Iceland Sea during the Early Pliocene, when the global climate was warmer than present. However, conclusive evidence as well as potential mechanisms governing sea ice occurrence outside the Arctic Ocean during a time with elevated greenhouse gas concentrations are still elusive. Here we present a suite of organic ...
    • The onset of flysch sedimentation in the Kaoko Belt (NW Namibia) – Implications for the pre-collisional evolution of the Kaoko–Dom Feliciano–Gariep orogen 

      Konopásek, Jiří; Hoffmann, Karl Heinz; Sláma, Jiří; Košler, Jan (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-17)
      <p>Detrital zircon provenance study of a metamorphosed sedimentary succession in the eastern part of the Kaoko Belt in Namibia has revealed two distinct sources for the Neoproterozoic sedimentation along the southwestern Congo Craton margin. The lower part of the succession shows detrital zircon ages consistent with erosion of Paleoproterozoic basement of the Congo Craton with an inferred Mesoproterozoic ...
    • Optimising the use of marine tephrochronology in the North Atlantic: a detailed investigation of the Faroe Marine Ash Zones II, III and IV 

      Griggs, Adam J.; Davies, Siwan M.; Abbott, Peter M.; Rasmussen, Tine Lander; Palmer, A. P. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Organic Matter Sources in North Atlantic Fjord Sediments 

      Faust, Johan Christoph; Knies, Jochen (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-31)
      To better constrain the global carbon cycle fundamental knowledge of the role of carbon cycling on continental margins is crucial. Fjords are particularly important shelf areas for carbon burial due to relatively high sedimentation rates and high organic matter fluxes. As terrigenous organic matter is more resistant to remineralization than marine organic matter, a comprehensive knowledge of the ...
    • Origin and K-Ar age of the phreatomagmatic breccia at the Trepča Pb-Zn-Ag skarn deposit, Kosovo: Implications for ore-forming processes 

      Strmic Palinkas, Sabina; Palinkaš, Ladislav A.; Mandić, Magda; Roller-Lutz, Zvjezdana; Pécskay, Zoltan; Maliqi, Gani; Bermanec, Vladimir (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-29)
      The Trepča Pb-Zn-Ag skarn deposit in Kosovo is spatially and temporarily related to the phreatomagmatic breccia of Oligocene age (~23Ma). The deposit shows features typical for skarn deposits worldwide, including a stage of isochemical metamorphism, a prograde stage of an anhydrous, low oxygen and low sulfur fugacity character, and a retrograde stage characterized by an increase in the water ...
    • Origin and Periodic Behavior of Short Duration Signals Recorded by Seismometers at Vestnesa Ridge, an Active Seepage Site on the West-Svalbard Continental Margin 

      Domel, Przemyslaw; Singhroha, Sunny; Plaza-Faverola, Andreia; Schlindwein, Vera; Ramachandran, Hariharan; Bünz, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-02)
      Short duration events (SDEs) are reported worldwide from ocean-bottom seismometers (OBSs). Due to their high frequency (4–30 Hz) and short duration, they are commonly attributed to aseismic sources, such as fluid migration related processes from cold seeps, biological signals, or noise. We present the results of a passive seismic experiment that deployed an OBS network for 10-month (October 2015–July ...
    • Origin and transformation of light hydrocarbons ascending at an active pockmark on Vestnesa Ridge, Arctic Ocean 

      Pape, Thomas; Buenz, Stefan; Hong, Wei-Li; Torres, Marta E.; Riedel, Matthias; Panieri, Giuliana; Lepland, Aivo; Hsu, Chieh Wei; Wintersteller, Paul; Wallmann, Klaus; Schmidt, Christopher; Yao, Haoyi; Bohrmann, Gerhard (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-25)
      We report on the geochemistry of hydrocarbons and pore waters down to 62.5 mbsf, collected by drilling with the MARUM‐MeBo70 and by gravity coring at the Lunde pockmark in the Vestnesa Ridge. Our data document the origin and transformations of volatiles feeding gas emissions previously documented in this region. Gas hydrates are present where a fracture network beneath the pockmark focusses migration ...
    • The origin of driftwood on eastern and south-western Svalbard 

      Linderholm, Hans W.; Gunnarson, Björn E.; Fuentes, Mauricio; Büntgen, Ulf; Hormes, Anne (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-02)
      The Arctic is one of the regions where the effect of global change is most evident. Associated with warming are changes in snow, sea ice and hydroclimate, all which have significant impacts on environments and society. However, due to short observational records, it is difficult to set the current climate in a long-term context. Arctic driftwood (DW), available throughout the Holocene, is a paleoclimate ...
    • The Origin of Gas Seeps in the Northern Adriatic Sea 

      Donda, Federica; Tinivella, Umberta; Gordini, Emiliano; Panieri, Giuliana; Volpi, Valentina; Civile, Dario; Forlin, Edy; Facchin, Lorenzo; Burca, Mihai; Cova, Andrea; Ferrante, Giulia M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06)
      A multidisciplinary approach has been used for the first time to study the widespread occurrence of hydrocarbon seeps in the northern Adriatic Sea. Geological, geophysical and geochemical analyses were performed to identify and characterize the gas-charged fluids occurring throughout the Plio-Quaternary succession, and to date the shallow gas seeping at three leakage sites. The analysis of CHIRP, ...
    • Oxygenated conditions in the aftermath of the Lomagundi-Jatuli Event: The carbon isotope and rare earth element signatures of the Paleoproterozoic Zaonega Formation, Russia 

      Kreitsmann, T.; Lepland, Aivo; Bau, M.; Prave, A.R.; Paiste, Kärt; Mänd, K.; Sepp, H.; Martma, T.; Romashkin, A.E; Kirsimäe, K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-09)
      The c. 2.0 Ga Zaonega Formation of the Onega Basin (NW Russia) has been central in efforts to understand what led to the initial rise (Great Oxidation Event, GOE) and postulated fall in free atmospheric oxygen and associated high-amplitude carbon cycle excursions, the Lomagundi-Jatuli Event (LJE) and subsequent Shunga Event during Paleoproterozoic time. The Formation accumulated shortly after the ...
    • Palaeoceanographic and environmental changes in the eastern Fram Strait during the last 14,000 years based on benthic and planktonic foraminifera 

      Consolaro, Chiara; Rasmussen, Tine Lander; Panieri, Giuliana (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-14)
      Benthic and planktonic foraminifera, stable isotopes and other geochemical and sedimentological parameters have been investigated in a sediment core from Vestnesa Ridge (79°N, NW Svalbard margin, 1300 m water depth) in order to reconstruct the palaeoceanographic and palaeoenvironmental evolution of the eastern Fram Strait during the last 14,000 years. Our multiproxy data and, in particular, our ...
    • Palaeoceanographic reconstruction of surface-ocean changes in the southern Norwegian Sea for the last ~130,000 years based on diatoms and with comparison to foraminiferal records 

      Hoff, Ulrike; Rasmussen, Tine Lander; Meyer, Hanno; Koc, Nalan; Hansen, Jesper (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-28)
      Fossil marine diatom assemblages in a sediment core from the central northern Faroe slope in the Norwegian Sea were used to reconstruct palaeoceanographic changes in the surface water mixed layer from the last ~130,000 years (Marine Isotope Stage (MIS) 6/5 transition to MIS 1 (including the Eemian and Holocene interglacials) and to compare the results with previously published results on planktic ...
    • Palaeoceanography of the Barents Sea continental margin, north of Nordaustlandet, Svalbard, during the last 74 ka 

      Chauhan, Teena; Rasmussen, Tine Lander; Noormets, Riko (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-17)
      We investigated gravity core HH11‐09GC from 488 m water depth at the northern Svalbard margin in order to reconstruct changes in Atlantic Water (AW) inflow to the Arctic Ocean. The study was based on the distribution patterns of benthic and planktic foraminifera, benthic and planktic oxygen and carbon isotopes, lithology and physical properties of the sediments. The core contains sediments from ...
    • Palaeoproterozoic foreland fold-thrust belt structures and lateral faults in the West Troms Basement Complex, northern Norway, and their relation to inverted metasedimentary sequences 

      Paulsen, Hanne-Kristin; Bergh, Steffen G; Palinkas, Sabina Strmic; Karlsen, Siri; Kolsum, Sofie; Rønningen, Ida Ulvik; Armitage, Paul E.B.; Nasuti, Aziz (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-15)
      Palaeoproterozoic fold-thrust belt structures and steep, lateral shear zones characterize the foreland deformation of Neoarchaean basement tonalites in Vanna, West Troms Basement Complex, northern Norway. Low-grade par-autochthonous and allochthonous cover units (2.4–2.2. Ga) with sandstones and calcareous metapelites exist in separate areas of the foreland. They were formed as intracontinental rift- ...
    • The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System 

      Orvik, Alf Andre; Slagstad, Trond; Hansen, Harald; Nilsson, Lars Petter; Sørensen, Bjørn Eske (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-14)
      The modern concepts of magmatic plumbing systems have evolved from simple models of melt-dominated crustal magma chambers to magmatic systems that span the continental crust. The geochemistry of these systems is challenging to model numerically because of a complex polybaric and multiphase evolution, which is not well described by mathematic end-member formulas. We propose that a recent modelling ...
    • Palaeoproterozoic oxygenated oceans following the Lomagundi–Jatuli Event 

      Mänd, Kaarel; Lalonde, Stefan V.; Robbins, Leslie J.; Thoby, Marie; Paiste, Kärt; Kreitsmann, Timmu; Paiste, Päärn; Reinhard, Christopher T.; Romashkin, Alexandr E.; Planavsky, Noah J.; Kirsimäe, Kalle; Lepland, Aivo; Konhauser, Kurt O. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-16)
      The approximately 2,220–2,060 million years old Lomagundi–Jatuli Event was the longest positive carbon isotope excursion in Earth history and is traditionally interpreted to reflect an increased organic carbon burial and a transient rise in atmospheric O<sub>2</sub>. However, it is widely held that O<sub>2</sub> levels collapsed for more than a billion years after this. Here we show that black shales ...