Blar i forfatter "Helland-Hansen, William"

Viser treff 1-6 av 6

    • Deep-water sand transfer by hyperpycnal flows, the Eocene of Spitsbergen, Arctic Norway 

      Grundvåg, Sten-Andreas; Helland-Hansen, William; Johannessen, Erik P.; Eggenhuisen, Joris T.; Pohl, Florian; Spychala, Yvonne T. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-11)
      Flood-generated hyperpycnal flows are dense, sediment-laden, turbulent flows that can form long-lived, bottom-hugging turbidity currents, which undoubtedly transport large volumes of fine-grained sediments into the ocean. However, their ability in transferring sand into deep-water basins is debated. This study presents sedimentological evidence of sandy hyperpycnal flow deposits (hyperpycnites) in ...

    • Evidence of hyperpycnally fed turbidites in a basin floor setting, Eocene of Spitsbergen, Arctic Norway 

      Grundvåg, Sten-Andreas; Helland-Hansen, William (Conference object; Konferansebidrag, 2018)
      The Eocene of Spitsbergen, Svalbard, has received considerable attention in the literature because of its spectacular seismic-scale clinoforms exposed along many fiords and valleys. Previous investigations particularly focused on the slope segment of the clinoforms and demonstrated how sustained-type, hyperpycnal flows deriving from shelf-edge deltas played a major role in bringing sand onto the ...

    • Progradation rates measured at modern river outlets: A first-order constraint on the pace of deltaic deposition 

      Aadland, Tore; Helland-Hansen, William (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-29)
      We present a compilation of modern shoreline progradation rates measured close to river outlets entering deltaic coastlines, and we discuss how these observations relate to the overall evolution of both modern and ancient deltaic coastlines. We analyzed Landsat‐derived satellite images to identify plan view changes in the subaerial morphology of 331 modern deltaic coastlines. Our rate compilation ...

    • The Svalbard Eocene-Oligocene (?) Central Basin succession: Sedimentation patterns and controls 

      Helland-Hansen, William; Grundvåg, Sten-Andreas (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-12)
      A synthesis has been undertaken based on regionally compiled data from the post early Eocene foreland basin succession of Svalbard. The aim has been to generate an updated depositional model and link this to controlling factors. The more than kilometer thick progradational succession includes the offshore shales of the Gilsonryggen Member of the Frysjaodden Formation, the shallow marine sandstones ...

    • Tempestite facies variability and storm‐depositional processes across a wide ramp: Towards a polygenetic model for hummocky cross‐stratification 

      Jelby, Mads Engholm; Grundvåg, Sten-Andreas; Helland-Hansen, William; Olaussen, Snorre; Stemmerik, Lars (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-03)
      The hydrodynamic mechanisms responsible for the genesis and facies variability of shallow‐marine sandstone storm deposits (tempestites) have been intensely debated, with particular focus on hummocky cross‐stratification. Despite being ubiquitously utilized as diagnostic elements of high‐energy storm events, the full formative process spectrum of tempestites and hummocky cross‐stratification is still ...

    • 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 ...