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  • 1
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    Zambezi continental margin: compartmentalized sediment transfer routes to the abyssal Mozambique Channel (2017)
    Springer
    In:  EPIC3Marin Geophysical Research, Springer, 38(3), pp. 227-240
    Details
    Publikationsdatum: 2017-09-10
    Beschreibung: Sediment delivery to the abyssal regions of the oceans is an integral process in the source to sink cycle of material derived from adjacent continents and islands. The Zambezi River, the largest in southern Africa, delivers vast amounts of material to the inner continental shelf of central Mozambique. The aim of this contribution is to better constrain sediment transport pathways to the abyssal plains using the latest, regional, high-resolution multibeam bathymetry data available, taking into account the effects of bottom water circulation, antecedent basin morphology and sea-level change. Results show that sediment transport and delivery to the abyssal plains is partitioned into three distinct domains; southern, central and northern. Sediment partitioning is primarily controlled by changes in continental shelf and shelf-break morphology under the influence of a clockwise rotating shelf circulation system. However, changes in sealevel have an overarching control on sediment delivery to particular domains. During highstand conditions, such as today, limited sediment delivery to the submarine Zambezi Valley and Channel is proposed, with increased sediment delivery to the deepwater basin being envisaged during regression and lowstand conditions. However, there is a pronounced along-strike variation in sediment transport during the sea-level cycle due to changes in the width, depth and orientation of the shelf. This combination of features outlines a sequence stratigraphic concept not generally considered in the strike-aligned shelf-slope-abyssal continuum.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Standort Signatur Einschränkungen Verfügbarkeit
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    ARTIKEL (OA)
  • 2
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    Opening of the Fram Strait led to the establishment of a modern-like three-layer stratification in the Arctic Ocean during the Miocene (2021)
    Springer
    In:  EPIC3arktos, Springer, ISSN: 2364-9461
    Details
    Publikationsdatum: 2021-02-14
    Beschreibung: The tectonic opening of the Fram Strait (FS) was critical to the water exchange between the Atlantic Ocean and the Arctic Ocean, and caused the transition from a restricted to a ventilated Arctic Ocean during early Miocene. If and how the water exchange between the Arctic Ocean and the North Atlantic influenced the global current system is still disputed. We apply a fully coupled atmosphere–ocean–sea-ice model to investigate stratification and ocean circulation in the Arctic Ocean in response to the opening of the FS during early-to-middle Miocene. Progressive widening of the FS gateway in our simulation causes a moderate warming, while salinity conditions in the Nordic Seas remain similar. On the contrary, with increasing FS width, Arctic temperatures remain unchanged and salinity changes appear to steadily become stronger. For a sill depth of ~ 1500 m, we achieve ventilation of the Arctic Ocean due to enhanced import of saline Atlantic water through an FS width of ~ 105 km. Moreover, at this width and depth, we detect a modern-like three-layer stratification in the Arctic Ocean. The exchange flow through FS is characterized by vertical separation of a low-salinity cold outflow from the Arctic Ocean confined to a thin upper layer, an intermediate saline inflow from the Atlantic Ocean below, and a cold bottom Arctic outflow. Using a significantly shallower and narrower FS during the early Miocene, our study suggests that the ventilation mechanisms and stratification in the Arctic Ocean are comparable to the present-day characteristics.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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    ARTIKEL (OA)
  • 3
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    Geophysical indications of gas hydrate occurrence on the Greenland continental margins (2022)
    Springer
    In:  EPIC3World Atlas of Submarine Gas Hydrates in Continental Margins, World Atlas of Submarine Gas Hydrates in Continental Margins, Springer, 514 p., pp. 263-273
    Details
    Publikationsdatum: 2022-09-04
    Beschreibung: The glaciated Greenland continental margins contain favorable conditions for hydrate formation if gas is present. No gas hydrates have been encountered in the drilling of offshore wells, however, and only a limited focus has been placed on academic-led hydrate research to date. Nevertheless, analyses of 2D and 3D seismic reflection data have revealed the occurrence of BSRs, DHIs, chimneys and pockmarks. These seismic features all suggest the presence of gas and gas hydrates within three different sections of the Greenland margin. Seismic amplitude observations in Melville Bay, offshore northwest Greenland, indicate the existence of a *220 m thick gas hydrate deposit over a 50 m high gas column. It is suggested that the paleo-topography of the area has forced the migration of fluid into the overlying stratigraphy. In the Disco area, offshore central West Greenland, seismic observations together with heatflow measurements and sediment core samples suggest that gas and gas hydrates exist in regions with sub-cropping Cretaceous to Paleocene strata and in areas covered by thick postglacial sediments. Finally, 2D seismic reflection data indicate gas and gas hydrate deposits of potentially abiotic origin within the northeast Greenland margin and Molloy Basin, adjacent to the ocean spreading systems in the Fram Strait.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Inbook , NonPeerReviewed
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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    ARTIKEL (OA)
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