Viser treff 659-678 av 711

    • Testing miniaturized extraction chromatography protocols for combined 87Sr/86Sr and δ88/86Sr analyses of pore water by MC‐ICP‐MS 

      Argentino, Claudio; Lugli, Federico; Cipriani, Anna; Panieri, Giuliana (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-04)
      We tested two miniaturized extraction chromatography protocols for strontium isolation based on 300 μL (Protocol 1) and 30 μL (Protocol 2) column volumes of Sr‐Spec resin, for the simultaneous determination of 87Sr/86Sr and δ88/86Sr by MC‐ICP‐MS. The accuracy and precision of the Sr isotope ratios have been evaluated by analyzing JCt‐1 and SRM 1640a reference materials, resulting in a reproducibility ...
    • A Theoretical Model of Drumlin Formation Based on Observations at Múlajökull, Iceland 

      Iverson, N. R.; McCracken, R. G.; Zoet, L. K.; Benediktsson, Í. Ö.; Schomacker, Anders; Johnson, M. D.; Woodard, J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-20)
      The drumlin field at the surge‐type glacier, Múlajökull, provides an unusual opportunity to build a model of drumlin formation based on field observations in a modern drumlin‐forming environment. These observations indicate that surges deposit till layers that drape the glacier forefield, conform to drumlin surfaces, and are deposited in shear. Observations also indicate that erosion helps create ...
    • Thermal Characterization of Pockmarks Across Vestnesa and Svyatogor Ridges, Offshore Svalbard 

      Riedel, M.; Villinger, H.; Freudenthal, T.; Pape, T.; Bünz, Stefan; Bohrmann, G. (Journal article; Tidsskriftartikkel, 2020-11-10)
      The Svalbard margin represents one of the northernmost gas hydrate provinces worldwide. Vestnesa Ridge (VR) and Svyatogor Ridge (SR) west of Svalbard are two prominent sediment drifts showing abundant pockmarks and sites of seismic chimney structures. Some of these sites at VR are associated with active gas venting and were the focus of drilling and coring with the seafloor‐deployed MARUM‐MeBo70 ...
    • Thermal state of the Guaymas Basin derived from gas hydrate bottom simulating reflections and heat flow measurements 

      Sarkar, Sudipta; Moser, Manuel; Berndt, Christian; Doll, Mechthild; Böttner, Christoph; Chi, Wu-Cheng; Klaeschen, Dirk; Galerne, Christophe; Karstens, Jens; Geilert, Sonja; Mortera-Gutierrez, C.; Hensen, Christian (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-20)
      Seafloor heat flow provides information about the thermal evolution of the lithosphere, the magnitude and timing of volcanic activity, and hydrothermal circulation patterns. In the central Gulf of California, the Guaymas Basin is part of a young marginal spreading rift system that experiences high sedimentation (1–5 km/Myr) and widespread magmatic intrusions in the axial troughs and the off-axis ...
    • Thermogenic methane injection via bubble transport into the upper Arctic Ocean from the hydrate-charged Vestnesa Ridge, Svalbard 

      Smith, Andrew James; Mienert, Jurgen; Bünz, Stefan; Greinert, Jens (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-04-21)
      We use new gas‐hydrate geochemistry analyses, echosounder data, and three‐dimensional P‐Cable seismic data to study a gas‐hydrate and free‐gas system in 1200 m water depth at the Vestnesa Ridge offshore NW Svalbard. Geochemical measurements of gas from hydrates collected at the ridge revealed a thermogenic source. The presence of thermogenic gas and temperatures of ∼3.3°C result in a shallow top of ...
    • Tidal Energy Loss, Internal Tide Radiation, and Local Dissipation for Two-Layer Tidal Flow over a Sill 

      Arneborg, Lars; Jansson, Pær; Staalstrøm, Andre; Broström, Göran (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-14)
      A simple analytical model for tidal energy loss at fjord sills and its partitioning into local dissipation and radiated internal tides is presented. The analytical model builds on a two-layer assumption with quasi-steady nonlinear flow over the sill and wave radiation in the far field. When the interface is situated above sill level, upstream- and downstream-propagating internal waves are generated ...
    • Til IBGs 20-års-jubileum 

      Labugt, Sylvia (Kronikk; Chronicle, 1992)
    • A time-transgressive perspective of glacial erosion and meltwater beneath the Eurasian ice sheet 

      Patton, Henry Jared; Hubbard, Alun Lloyd; Heyman, Jakob; Alexandropoulou, Nikolitsa; Lasabuda, Amando P. E.; Stroeven, Arjen P; Hall, Adrian; Winsborrow, Monica Caroline Mackay; Sugden, David A.; Kleman, Johan; Shackleton, Calvin; Da Silveira Ramos Esteves, Mariana; Bjarnadóttir, Lilja Rún; Andreassen, Karin Marie (Conference object; Konferansebidrag, 2023-08)
      The efficacy and controls governing glacial erosion over geological timescales are intricately linked yet remain poorly understood and contended. By assimilating geophysical data with modelling of the Eurasian Ice Sheet - the third largest Quaternary ice mass that spanned 49°N - 82°N - we decipher its erosional footprint during the last ~110 ka glacial cycle. Our results demonstrate extreme ...
    • Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet 

      Cremiere, Antoine; Lepland, Aivo; Chand, Shyam; Sahy, Diana; Condon, Daniel J.; Noble, Stephen R.; Martma, Tõnu; Thorsnes, Terje; Sauer, Simone; Brunstad, Harald (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-11)
      Gas hydrates stored on continental shelves are susceptible to dissociation triggered by environmental changes. Knowledge of the timescales of gas hydrate dissociation and subsequent methane release are critical in understanding the impact of marine gas hydrates on the ocean–atmosphere system. Here we report a methane efflux chronology from five sites, at depths of 220–400 m, in the southwest Barents ...
    • TitaniQ temperatures and textural analysis as a record of the deformation history in a major continental shear zone system, Borborema Province, Brazil 

      Cavalcante, Carolina; de Jesus Costa, Juliana; Lagoeiro, Leonardo; Fossen, Haakon; Lee, Amicia; Archanjo, Carlos; Vizeu, Roberto (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-01)
      We combine quartz textural analysis with Titanium-in-quartz (TitaniQ) geothermometry to investigate the late stages of deformation in mylonitic rocks from the Sucuru dike swarm in the Borborema Province. The wide range in TitaniQ temperatures (>340 to 740 °C) closely related to grain sizes are attributed to inefficient Ti resetting during bulging (BLG) and subgrain rotation (SGR) recrystallization. ...
    • Towards an improved organic carbon budget for the western Barents Sea shelf 

      Pathirana, Irene Dorothea; Knies, Jochen; Felix, Maarten; Mann, Ute (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-03-21)
      There is generally a lack of knowledge on how marine organic carbon accumulation is linked to vertical export and primary productivity patterns in the Arctic Ocean. Despite the fact that annual primary production in the Arctic has increased as a consequence of shrinking sea ice, its effect on flux, preservation, and accumulation of organic carbon is still not well understood. In this study, a ...
    • Tracing Lower Cretaceous organic-rich units across the SW Barents Shelf 

      Hagset, Andreas Hallberg; Grundvåg, Sten-Andreas; Badics, Balazs; Davies, R; Rotevatn, Atle (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-28)
      On the Barents Shelf, the northernmost and least explored hydrocarbon province of the Norwegian Continental Shelf, Upper Jurassic organic-rich shales have traditionally been given most attention as these represent the most prolific source rock unit of the region. However, in the western frontier areas of the Barents Shelf, the Upper Jurassic is too deeply buried. By combining high-resolution 2D ...
    • 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 ...