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S.B. Nielsen

Climate vs. tectonic induced variations in Cenozoic sediment supply from western Scandinavia

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  • Department of Earth Sciences
The rates of sediment input to the North Sea and the Norwegian Shelf varied significantly during the Cenozoic. During Paleocene and Eocene times The Shetland Platform and Scottish Highlands were the main sediment sources, while with the onset of the Oligocene more sediment was coming from the Scandinavian shield. This is believed mainly to be a consequence of varying erosion rates and/or changes in sediment catchments in Western Scandinavia and has previously been interpreted in terms of variable tectonic uplift of the area caused by a hitherto unknown tectonic agent. During Paleocene to Early Eocene times tectonic activity related to the final stage of opening of the North Atlantic was apparently controlling the sediment input in the North Sea as sediment pulses correlate well with tectonic events. Although there is no signs of Cenozoic tectonic activity onshore Scandinavia (igneous bodies, faulting), tectonic disturbance related to ocean opening could be responsible for deposition of thick Paleocene wedges along the western coast of Norway. During subsequent Cenozoic periods domal structures in the Norwegian shelf are a proof for mild and protracted compression. However, depositional patterns from offshore Scandinavia have been interpreted as a result of significant tectonic movements. In the absence of proofs for active tectonic agents we attempt to explain these sediment input variations as a result of climate fluctuations. The Eocene-Oligocene greenhouse-icehouse climate transition corresponds to an increase of sediment yield from the Scandinavian shield. Furthermore, several studies show a correlation between climate fluctuations, sequence stratigraphic surfaces and lithological changes in the North Sea. We suggest that a rapid cooling at the beginning of Oligocene (Oi-1 glaciation) changed the erosional regime in western Scandinavia from fluvial (inefficient in tectonically stable settings, almost regardless of the amount of precipitation) to glacial. Glacial erosion is much more effective and is apparently able to outpace tectonic processes responsible for development of high topography. Therefore, a hypothesis of climate control on erosion and deposition during the Cenozoic history of western Scandinavia and adjacent sedimentary basins emerges. This theory is further supported by higher sediment input and pronounced progradation patterns of the Molo Formation (deposited during Late Miocene-Early Pliocene cooling) and the spectacular prograding wedges of Naust Formation (with onset of deposition at around 2.8 Ma, matching the Pliocene ‘climate crash’)
Original languageEnglish
Publication year2010
Number of pages1
Publication statusPublished - 2010
EventFrom Depositional Systems to Sedimentary Successions on the Norwegian Continental Shelf - Stavanger, Norway
Duration: 4 May 20106 May 2010

Conference

ConferenceFrom Depositional Systems to Sedimentary Successions on the Norwegian Continental Shelf
CountryNorway
CityStavanger
Period04/05/201006/05/2010

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