Viser treff 671-690 av 711

    • Tracing Subducted Carbonates in Earth's Mantle Using Zinc and Molybdenum Isotopes 

      Wang, Jian; Tang, Gong-Jian; Tappe, Sebastian; Li, Jie; Zou, Zongqi; Wang, Qiang; Su, Yu-Ping; Zheng, Jian-Ping (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-23)
      Although carbonates are the primary form of carbon subducted into the mantle, their fate during recycling is debated. Here we report the first coupled high-precision Zn and Mo isotope data for Cenozoic intraplate basalts from western China. The exceptionally high δ<sup>66</sup>Zn values (+0.39 to +0.50‰) of these lavas require involvement of recycled carbonates in the mantle source. Variable ...
    • Transferring grains from single-grain luminescence discs to SEM specimen stubs 

      Doverbratt, Isa; Alexanderson, Helena (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-21)
      The grain transfer protocol presents a step-by-step guide on how to successfully transfer positioned grains from a single-grain luminescence disc to a scanning electron microscope (SEM) specimen stub and how to transport them between laboratories. Single-grain luminescence analysis allows the determination of luminescence characteristics for individual sand-sized grains. By combining such luminescence ...
    • Transformation weakening: Diffusion creep in eclogites as a result of interaction of mineral reactions and deformation 

      Stunitz, Holger; Neufeld, Kai; Heilbronner, Renée; Finstad, Ane Kongsro; Konopásek, Jiří; Mackenzie, James R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-09)
      The deformation of eclogites and the driving forces for their fabric development are an important topic, potentially allowing to determine deformation rates and stresses in subduction zones, where the greatest number of large earthquakes occurs. Here, fabric studies of grain size and shape, texture, and chemical composition from two locations of Variscan and Alpine eclogites are presented. All samples ...
    • The transition from normal marine to evaporitic conditions recorded in a cold seep environment: The Messinian succession of Northern Italy 

      Conti, S.; Argentino, Claudio; Bojanowski, M.; Fioroni, C.; Giunti, S.; Kremer, B.; Fontana, D. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-26)
      Messinian pre-evaporitic seep carbonates outcropping in the Tuscan-Romagna area share a common upward stratigraphic trend: massive seep carbonates rich in large lucinids, modiolids and planktonic foraminifera pass upward to horizontally laminated carbonates free of macrofauna and foraminifera. A transitional macrofauna-free facies marks the passage in some sections, sometimes with faint lamination. ...
    • Transpressive strain partitioning between the Major Gercino Shear Zone and the Tijucas Fold Belt, Dom Feliciano Belt, Santa Catarina, southern Brazil 

      De Toni, Giuseppe Betino; Bitencourt, Maria de Fatima; Konopásek, Jiří; Martini, Amos; Andrade, Pedro; Florisbal, Luana Moreira; Campos, Roberto Sacks de (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-15)
      A composite cross section from the Florianópolis Batholith towards the Tijucas Fold Belt in the northern Dom Feliciano Belt (southern Brazil) is divided in three structural domains: the Major Gercino Shear Zone, the suprastructural Brusque Complex and the infrastructural Camboriú Complex. A kinematic correlation among the structural domains is based on structural and petrological data integrated ...
    • Trap and seal analysis of the northern Barents Shelf 

      Paulsen, Renate Strugstad (Conference object; Konferansebidrag, 2018)
      Although the majority of exploration wells in the Barents Sea has encountered hydrocarbons, only two fields, the Snøhvit (gas) and Goliat (oil) fields are currently in production. The geological evolution of the area, including previous deep burial and subsequent exhumation, has contributed to the leakage of hydrocarbon from many traps. Understanding the timing of hydrocarbon generation and migration, ...
    • Turbidites in the Eocene of Spitsbergen: Can they tell us something about the Sørvestsnaget Basin? 

      Grundvåg, Sten-Andreas; Helland-Hansen, William; Safronova, Polina (Conference object; Konferansebidrag, 2017)
      <p>The Eocene of Spitsbergen, Svalbard, has received considerable attention in the literature because of its spectacular seismic-scale clinforms exposed along many fiords and valleys. High quality outcrops enables downdip tracing of facies belts from the proximal shelf through the shelf-edge and down-slope into the basin floor. Previous publications particularly focused on the shelf-edge to slope ...
    • Two-billion-year-old evaporites capture Earth’s great oxidation 

      Blättler, C.L.; Claire, M.W.; Prave, A.R.; Kirsimäe, K.; Higgins, J.A.; Medvedev, P.V.; Romashkin, A.E; Rychanchik, D.V.; Zerkle, A.L.; Paiste, Kärt; Kreitsmann, T.; Millar, I.L.; Hayles, J.A.; Bao, H.; Turchyn, A.V.; Warke, M.R.; Lepland, Aivo (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-20)
      Major changes in atmospheric and ocean chemistry occurred in the Paleoproterozoic era (2.5 to 1.6 billion years ago). Increasing oxidation dramatically changed Earth’s surface, but few quantitative constraints exist on this important transition. This study describes the sedimentology, mineralogy, and geochemistry of a 2-billion-year-old, ~800-meter-thick evaporite succession from the Onega Basin in ...
    • Two-stage exhumation of subducted Saxothuringian continental crust records underplating in the subduction channel and collisional forced folding (Krkonoše-Jizera Mts., Bohemian Massif) 

      Jerabek, Petr; Konopasek, Jiri; Žáčková, Eliška (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-08)
      The Krkonoše-Jizera Massif in the northern part of the Variscan Bohemian Massif provides insight into the exhumation mechanisms for subducted continental crust. The studied region exposes a relatively large portion of a flat-lying subduction-related complex that extends approximately 50 km away from the paleosuture. wide extent of HP-LT metamorphism has been confirmed by new P-T estimates indicating ...
    • U-Th chronology and formation controls of methane-derived authigenic carbonates from the Hola trough seep area, northern Norway 

      Sauer, Simone; Knies, Jochen; Lepland, Aivo; Sahy, Diana; Martma, Tõnu; Noble, Stephen R.; Schönenbergerb, Jasmin; Klug, Martin; Schubert, Carsten J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-20)
      We investigated methane-derived authigenic carbonate (MDAC) crusts and nodules from a cold seep site on the northern Norwegian continental shelf in ca. 220 m water depth to determine the timing and mode of their formation. Gas bubbling observed during remotely operated vehicle (ROV)-assisted sampling of MDAC crusts revealed ongoing seep activity. Authigenic carbonates were present as crusts on the ...
    • UAV photogrammetry and structure from motion to assess calving dynamics at Store Glacier, a large outlet draining the Greenland ice sheet 

      Ryan, Johnny C.; Hubbard, Alun Lloyd; Box, Jason E.; Todd, Joe; Christoffersen, Poul; Carr, J. Rachel; Holt, Tom O.; Snooke, Neal A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-06)
      This study presents the application of a costeffective, unmanned aerial vehicle (UAV) to investigate calving dynamics at a major marine-terminating outlet glacier draining the western sector of the Greenland ice sheet. The UAV was flown over Store Glacier on three sorties during summer 2013 and acquired over 2000 overlapping, geotagged images of the calving front at an ∼ 40 cm ground sampling ...
    • Uncovering hidden structures: previously undescribed pseudopodia and ectoplasmic structures in planktonic foraminifera 

      Greco, Mattia; Westgård, Adele; Sykes, Freya Elizabeth; Mohamed, Mohamed Mahmoud Ezat Ahmed; Meilland, Julie (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-05)
      The trophic strategies of cold-water planktonic foraminifera are not well understood due to the challenge of culturing them in polar conditions. Here, we identify previously unknown ectoplasmic and cytoplasmic projections in three species of planktonic foraminifera thriving in polar and subpolar marine environments: Globigerina bulloides, Neogloboquadrina incompta and Neogloboquadrina pachyderma. ...
    • Underexplored continental shelf gateways: timing, mechanisms and role of SW Barents Sea Gateway, Norwegian Arctic 

      Lasabuda, Amando P. E.; Hanssen, Alfred; Laberg, Jan Sverre; Rydningen, Tom Arne; Patton, Henry; Faleide, Jan Inge; Abdelmalak, Mohamed Mansour; Kjølhamar, Bent (Conference object; Konferansebidrag, 2022)
      Ocean gateways connecting ocean basins are crucial for water and heat circulation, which influence global temperature, climate evolution and sediment distribution. While deep-water gateways have been a major research focus by the community, very little attention has been drawn to shallower gateways located on the continental shelves, where such circulation also takes place. In this study, we investigate ...
    • Undersjøiske daler og oljereservoar 

      Vorren, Tore Ola; Laberg, Jan Sverre (Chronicle; Kronikk, 2010-10-02)
    • Undersjøiske kjempeskred og flodbølger 

      Vorren, Tore Ola; Laberg, Jan Sverre (Chronicle; Kronikk, 2010-09-25)
    • Unravelling key controls on the rift climax to post-rift fill of marine rift basins: insights from 3D seismic analysis of the Lower Cretaceous of the Hammerfest Basin, SW Barents Sea 

      Marin Restrepo, Dora Luz; Escalona Varela, Alejandro; Grundvåg, Sten-Andreas; Olaussen, Snorre; Sandvik, Sara; Śliwińska, Kasia K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-19)
      In this study, we investigate key factors controlling the rift climax to post‐rift marine basin fill. We use two‐ and three‐dimensional seismic data in combination with sedimentological core descriptions from the Hammerfest Basin, south‐western Barents Sea to characterize and analyse the tectonostratigraphy and seismic facies of the Lower Cretaceous succession. Based on our biostratigraphic analyses, ...
    • An updated Weichselian chronostratigraphic framework of the Kongsfjorden Trough Mouth Fan and its implications for the glacial history of Svalbard 

      Wiberg, Daniel Hesjedal; Haflidason, Haflidi; Laberg, Jan Sverre (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-02)
      The Arctic is a climate-sensitive area, responding rapidly to present changes, but for the past changes, the recordis still incomplete. Forinstance, theWeichselian glacial historyof the Svalbard–Barents Sea Ice Sheet (SBIS) haslargely been reconstructed based on studies of the fragmentary Spitsbergen terrestrial and shelf records. However, the sediments removed from the land and shelf areas during ...
    • Upper cretaceous-paleogene stratigraphy and development of the Mímir High, Vøring transform margin, Norwegian Sea 

      Polteau, Stephane; Planke, Sverre; Zastrozhnov, Dmitrii; Abdelmalak, Mohamed Mansour; Lebedeva-Ivanova, Nina; Eckhoff Planke, Ellen; Svensen, Henrik; Mazzini, Adriano; Gernigon, Laurent; Myklebust, Reidun; Kjølhamar, Bent; Pedersen, Rolf B.; Sandstå, Nils Rune; Bünz, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-19)
      Transform margins represent strike-slip type of plate boundaries that form during continental breakup and initial ocean opening. They are often characterized by margin-parallel highs with exposed pre- and syn-rift sequences. The Vøring Transform Margin, offshore mid-Norway, initiated in the earliest Eocene during the opening of the NE Atlantic. Here, 2D seismic reflection data reveal a transform ...
    • Using thermal UAV imagery to model distributed debris thicknesses and sub-debris melt rates on debris-covered glaciers 

      Bisset, Rosie R.; Nienow, Peter W.; Goldberg, Daniel N.; Wigmore, Oliver; Loayza-Muro, Raúl A.; Wadham, Jemma Louise; Macdonald, Moya L.; Bingham, Robert G. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-14)
      Supraglacial debris cover regulates the melt rates of many glaciers in mountainous regions around the world, thereby modifying the availability and quality of downstream water resources. However, the influence of supraglacial debris is often poorly represented within glaciological models, due to the absence of a technique to provide high-precision, spatially continuous measurements of debris thickness. ...
    • Variability in transport of terrigenous material on the shelves and the deep Arctic Ocean during the Holocene 

      Wegner, C.; Bennet, K.; Vernal, Anne de; Forwick, Matthias; Fritz, M.; Heikkilä, Maija; Łącka, Magdalena; Lantuit, Hugues; Laska, Michał; Moskalik, Mateusz; O’Regan, Matt; Pawłowska, J; Promińska, Agnieszka; Rachold, Volker; Vonk, Jorien E.; Werner, Kirstin (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-09)
      Arctic coastal zones serve as a sensitive filter for terrigenous matter input onto the shelves via river discharge and coastal erosion. This material is further distributed across the Arctic by ocean currents and sea ice. The coastal regions are particularly vulnerable to changes related to recent climate change. We compiled a pan-Arctic review that looks into the changing Holocene sources, transport ...