Now showing items 341-360 of 1011

    • Evolution of a shear zone before, during and after melting 

      Lee, Amicia; Lloyd, Geoffrey E.; Torvela, Taija; Walker, Andrew M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-03)
      Partial melt in the deforming mid- or lower continental crust causes a strength decrease and drives formation of lithological heterogeneities. However, mechanisms of formation of syn-melt deformation zones and strain partitioning in partially molten rock remain poorly understood. We use field and microstructural observations to unravel the evolution of a partial melt shear zone, Seiland Igneous ...
    • The Raunis section, central Latvia, revisited: first luminescence results and re-evaluation of a key Baltic States stratigraphic site 

      Kalińska, Edyta; Alexanderson, Helena; Krievāns, Māris (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-08)
      In interstadial deposits, sand interbeds gain limited consideration in comparison with organic sediments, and therefore tend to be underrepresented in paleoenvironmental reconstructions. The Raunis site, central-eastern Latvia, is an example where organic beds have already gained some attention and been used to understand the complex interactions between advance and retreat of the Scandinavian Ice ...
    • Neodymium isotope constraints on chemical weathering and past glacial activity in Svalbard 

      Jang, Kwangchul; Bayon, Germain; Han, Yeongcheol; Joo, Young Ji; Kim, Ji-Hoon; Ryu, Jong-Sik; Woo, Jusun; Forwick, Matthias; Szczuciński, Witold; Kim, Jung-Hyun; Nam, Seung-Il (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-15)
      <p>Neodymium (Nd) isotopes in leached authigenic components of marine sediments have been increasingly used as a tracer of past ocean-water masses. Despite the general assumption that the Nd isotopic composition of solutes released during chemical weathering fingerprints the source rocks on continents, preferential dissolution of easily dissolvable phases may result in significant deviations in Nd ...
    • The role of shelf morphology on storm-bed variability and stratigraphic architecture, Lower Cretaceous, Svalbard 

      Grundvåg, Sten-Andreas; Jelby, Mads Engholm; Olaussen, Snorre; Sliwinska, Kasia (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-13)
      The dominance of isotropic hummocky cross‐stratification, recording deposition solely by oscillatory flows, in many ancient storm‐dominated shoreface–shelf successions is enigmatic. Based on conventional sedimentological investigations, this study shows that storm deposits in three different and stratigraphically separated siliciclastic sediment wedges within the Lower Cretaceous succession in ...
    • Miocene Seep-Carbonates of the Northern Apennines (Emilia to Umbria, Italy): An Overview 

      Conti, Stefano; Argentino, Claudio; Fioroni, Chiara; Salocchi, Aura Cecilia; Fontana, Daniela (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-28)
      The natural emission of methane-rich fluids from the seafloor, known as cold seepage, is a widespread process at modern continental margins. The studies on present-day cold seepages provide high-resolution datasets regarding the fluid plumbing system, biogeochemical processes in the sediment, seafloor seepage distribution and ecosystems. However, the long-term (hundreds of thousands to millions of ...
    • Exhumation of the High‐Pressure Tsäkkok Lens, Swedish Caledonides: Insights From the Structural and White Mica 40Ar/39Ar Geochronological Record 

      Barnes, C.J.; Jeanneret, P.; Kullerud, Kåre; Majka, J.; Schneider, D.A.; Bukala, M.; Klonowska, I. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-12)
      Integrated structural, geochemical, and geochronological investigations were conducted on metasedimentary rocks in the eclogite-bearing Tsäkkok Lens of the Seve Nappe Complex (Scandinavian Caledonides) to resolve its exhumation history. Three deformation events are defined. D1 is likely related to the prograde to peak-metamorphic stages, represented by a locally preserved S1. D2 resulted in vertical ...
    • Feasibility of using the P-Cable high-resolution 3D seismic system in detecting and monitoring CO2 leakage 

      Waage, Malin; Singhroha, Sunny; Bünz, Stefan; Planke, Sverre; Waghorn, Kate Alyse; Bellwald, Benjamin (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-23)
      The P-Cable technology is an acquisition principle for high-resolution and ultra-high-resolution 3D seismic data. Many 3D seismic datasets have been acquired over the last decade, but the application in time-lapse studies for monitoring of CO2 storage is a new and intriguing topic. High-resolution 3D (HR3D) seismic has the potential to detect and monitor CO2 leakage at carbon capture and storage ...
    • Exceptions to bed-controlled ice sheet flow and retreat from glaciated continental margins worldwide 

      Greenwood, Sarah L.; Simkins, Lauren M; Winsborrow, Monica; Bjarnadóttir, Lilja Rún (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-13)
      Projections of ice sheet behavior hinge on how ice flow velocity evolves and the extent to which marine-based grounding lines are stable. Ice flow and grounding line retreat are variably governed by the coupling between the ice and underlying terrain. We ask to what degree catchment-scale bed characteristics determine ice flow and retreat, drawing on paleo-ice sheet landform imprints from 99 sites ...
    • 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 ...
    • Multiproxy paleoceanographic study from the western Barents Sea reveals dramatic Younger Dryas onset followed by oscillatory warming trend 

      Łącka, Magdalena; Michalska, Danuta; Pawłowska, Joanna; Szymańska, Natalia; Szczuciński, Witold; Forwick, Matthias; Zajączkowski, Marek (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-24)
      The Younger Dryas (YD) is recognized as a cool period that began and ended abruptly during a time of general warming at the end of the last glacial. New multi-proxy data from a sediment gravity core from Storfjordrenna (western Barents Sea, 253 m water depth) reveals that the onset of the YD occurred as a single short-lived dramatic environment deterioration, whereas the subsequent warming was ...
    • Seeing beyond the outcrop: Integration of ground-penetrating radar with digital outcrop models of a paleokarst system 

      Janocha, Julian; Smyrak-Sikora, Aleksandra; Senger, Kim; Birchall, Thomas (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-25)
      Paleokarst breccias are a common feature of sedimentary rift basins. The Billefjorden Trough in the High Arctic archipelago of Svalbard is an example of such a rift. Here the Carboniferous stratigraphy exhibits intervals of paleokarst breccias formed by gypsum dissolution. In this study we integrate digital outcrop models (DOMs) with a 2D ground penetrating radar (GPR) survey to extrapolate external ...
    • Pre-orogenic connection of the foreland domains of the Kaoko–Dom Feliciano–Gariep orogenic system 

      Percival, Jack James; Konopásek, Jiří; Eiesland, Ragnhild; Sláma, Jiří; Campos, Roberto Sacks de; Battisti, Matheus Ariel; Bitencourt, Maria de Fatima (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-30)
      Neoproterozoic metasedimentary rocks in the foreland domains of the Kaoko–Dom Feliciano–Gariep orogenic system record sedimentation from the breakup of Rodinia to the amalgamation of Gondwana, and thus provide ideal subjects for investigation of the mutual pre-orogenic positions of rifted margins of the African and South American cratonic blocks. U–Pb isotopic dating of zircon in the Brusque Complex ...
    • Compositional differences in dissolved organic matter between Arctic cold seeps versus non-seep sites at the Svalbard continental margin and the Barents sea 

      Sert, Muhammed Fatih; D’Andrilli, Juliana; Gründger, Friederike; Niemann, Helge; Granskog, Mats; Pavlov, Alexey K.; Ferré, Benedicte; Silyakova, Anna (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-07)
      Dissociating gas hydrates, submerged permafrost, and gas bearing sediments release methane to the water column from a multitude of seeps in the Arctic Ocean. The seeping methane dissolves and supports the growth of aerobic methane oxidizing bacteria (MOB), but the effect of seepage and seep related biogeochemical processes on water column dissolved organic matter (DOM) dynamics is not well ...
    • Evolution of metal-bearing fluids at the Nussir and Ulveryggen sediment-hosted Cu deposits, Repparfjord Tectonic Window, northern Norway 

      Mun, Yulia; Strmic Palinkas, Sabina; Kullerud, Kåre; Nilsen, Kjell S.; Neufeld, Kai; Bekker, Andrey (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-13)
      The Palaeoproterozoic greenstone belts of Fennoscandia are metamorphosed and deformed volcanic and sedimentary rocks that formed in basins with a high base-metal ore potential. One of these, the Repparfjord Tectonic Window (RTW), is exposed in the Caledonides of northern Norway and contains several sediment-hosted Cu deposits including Nussir and Ulveryggen. The RTW is composed of mafic metavolcanic ...
    • Dynamics of a retreating ice sheet: a LiDAR study in Värmland, SW Sweden 

      Goodship, Alastair; Alexanderson, Helena (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-11)
      Värmland in south western Sweden lies across the established zone of marine-terrestrial transition of the Scandinavian Ice Sheet (SIS) margin. The region lies inside the Younger Dryas maximum limit reached at 12.7 cal ka BP and the area of rapid final SIS retreat from 11.5 cal ka BP. LiDAR data across Värmland allows more detailed observation and analysis of glacial landforms formed during this stage ...
    • Climate and ocean forcing of ice-sheet dynamics along the Svalbard-Barents Sea Ice Sheet during the deglaciation 20,000–10,000 years BP 

      Rasmussen, Tine Lander; Thomsen, Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-11)
      The last deglaciation, 20,000–10,000 years ago, was a period of global warming and rapidly shrinking ice sheets. It was also climatically unstable and retreats were interrupted by re-advances. Retreat rates and timing relative to climatic changes have therefore been difficult to establish. We here study a suite of 12 marine sediment cores from Storfjorden and Storfjorden Trough, Svalbard. The purpose ...
    • Glacial history of the Åsgardfonna Ice Cap, NE Spitsbergen, since the last glaciation 

      Allaart, Lis; Schomacker, Anders; Larsen, Nicolaj K.; Nørmark, Egon; Rydningen, Tom Arne; Farnsworth, Wesley R.; Retelle, Michael J.; Brynjólfsson, Skafti; Forwick, Matthias; Kjellman, Sofia Elisabeth (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-30)
      The response of glaciers and ice caps to past climate change provides important insight into how they will react to ongoing and future global warming. In Svalbard, the Holocene glacial history has been studied for many cirque and valley glaciers. However, little is known about how the larger ice caps in Svalbard responded to Late Glacial and Holocene climate changes. Here we use lake sediment cores ...
    • Last glacial ice sheet dynamics offshore NE Greenland – a case study from Store Koldewey Trough 

      Olsen, Ingrid Leirvik; Rydningen, Tom Arne; Forwick, Matthias; Laberg, Jan Sverre; Husum, Katrine (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-04)
      The presence of a grounded Greenland Ice Sheet on the northeastern part of the Greenland continental shelf during the Last Glacial Maximum is supported by new swath bathymetry and high-resolution seismic data, supplemented with multi-proxy analyses of sediment gravity cores from Store Koldewey Trough. Subglacial till fills the trough, with an overlying drape of maximum 2.5 m thick glacier-proximal ...
    • 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 ...
    • Fault-controlled fluid circulation and diagenesis along basin-bounding fault systems in rifts - Insights from the East Greenland rift system 

      Salomon, Eric; Rotevatn, Atle; Kristensen, Thomas Berg; Grundvåg, Sten-Andreas; Henstra, Gijs Allard; Meckler, Anna Nele; Albert, Richard; Gerdes, Axel (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-05)
      In marine rift basins, deep-water clastics (>200 m) in the hanging wall of rift- or basin-bounding fault systems are commonly juxtaposed against crystalline “basement” rocks in the footwall. A distinct feature of such fault systems is therefore the juxtaposition of relatively highly permeable, unconsolidated sediments against relatively low-permeable basement rocks. Due to limited surface exposure ...