Aarhus University Seal / Aarhus Universitets segl

S.B. Nielsen

The offshore record of variable Cenozoic sediment flux 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 (Millennium

Atlas).

In general, the western Scandinavian sediment production rate increased from south to north, with more

than 500m of Oligocene deposits in the central and eastern North Sea (Huuse et al., 2001) to as much as 2000m

of Pliocene deposits in the Møre basin (Dehls et al., 2002). This is believed mainly to be a consequence of

varying erosion rates and/or changes in sediment catchments in Western Scandinavia. This has previously been

interpreted in terms of variable tectonic uplift of the area caused by a hitherto unknown tectonic agent; Neither

crustal shortening and thickening or magmatic underplating onshore, as well as other plate tectonic mechanisms,

are compatible with observations.

A dense grid of seismic data and well logs from numerous boreholes in the research area allow to estimate

the rate of deposition of matrix mass and to localize main areas of sediment outpour as a function of time. Here

we present semi-quantitative maps of sediment flux from western Scandinavia during subsequent epochs of the

Cenozoic and discuss possible explanations.

After a warm and ice-free Cretaceous period, the climate remained mild during Paleocene and Eocene

times. On the Eocene-Oligocene greenhouse-icehouse transition the sediment yield of the Scandinavian shield

increased. Furthermore, recent results (Heilmann-Clausen and van Simayes, 2005; Nielsen et al., 2008; Sliwinska

et al., 2008) show a correlation between climate fluctuations and sequence stratigraphic surfaces and lithological

changes in the North Sea. Based on this evidence we suggest that a rapid cooling at the beginning of Oligocene

(Oi-1 glaciation, Zachos et al., 2001) changed the erosional regime in western Scandianvia from fluvial (which

is inefficient in tectonically stable settings, regardless of the amount of precipitation - Von Blanckenburg, 2005)

to glacial. As, furthermore, glacial erosion (the glacial "buzzsaw" Mitchell and Montgomery, 2006; Brozovic et

al., 1997; Pedersen et al, 2008) and periglacial processes (Anderson, 2002) are known to possess the potential

for producing characteristic low-relief accordant landscapes at high elevation, this hypothesis also provides

and alternative to understanding flattish landscape elements in the western Scandinavian highlands, which

conventionally have been explained as remnants of uplifted peneplains previously graded to sea level (the Davisian

cyclic landscape evolution model).

Therefore, given the Eocene-Oligocene greenhouse-icehouse transition, which must have increased the importance

of glacial and periglacial erosion and transport processes in the highlands of western Scandinavia,

a hypothesis of climate control on erosional and depositional history of western Scandinavia and adjacent

sedimentary basins emerges. This hypothesis is to be tested using the present results. Estimation of offshore matrix

mass will be the basis for reconstruction of the development of source areas with use of mathematical models of

landscape evolution.

Original languageEnglish
JournalGeophysical Research Abstracts
Number of pages1
ISSN1607-7962
Publication statusPublished - 2009
EventEuropean Geosciences UnionGeneral Assembly 2009 - Vienna, Austria
Duration: 19 Apr 200924 Apr 2009

Conference

ConferenceEuropean Geosciences UnionGeneral Assembly 2009
CountryAustria
CityVienna
Period19/04/200924/04/2009

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