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| Titel |
Lithosphere and upper-mantle structure of the southern Baltic Sea estimated from modelling relative sea-level data with glacial isostatic adjustment |
| VerfasserIn |
H. Steffen, G. Kaufmann, R. Lampe |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 5, no. 1 ; Nr. 5, no. 1 (2014-06-10), S.447-459 |
| Datensatznummer |
250115278
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| Publikation (Nr.) |
 copernicus.org/se-5-447-2014.pdf |
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| Zusammenfassung |
During the last glacial maximum, a large ice sheet covered Scandinavia, which
depressed the earth's surface by several 100 m. In northern central Europe,
mass redistribution in the upper mantle led to the development of a
peripheral bulge. It has been subsiding since the begin of deglaciation due
to the viscoelastic behaviour of the mantle.
We analyse relative sea-level (RSL) data of southern Sweden, Denmark,
Germany, Poland and Lithuania to determine the lithospheric thickness and
radial mantle viscosity structure for distinct regional RSL subsets. We load
a 1-D Maxwell-viscoelastic earth model with a global ice-load
history model of the last glaciation. We test two commonly used ice
histories, RSES from the Australian National University and ICE-5G from the
University of Toronto.
Our results indicate that the lithospheric thickness varies, depending on the
ice model used, between 60 and 160 km. The lowest values are found in the
Oslo Graben area and the western German Baltic Sea coast. In between,
thickness increases by at least 30 km tracing the Ringkøbing-Fyn High. In
Poland and Lithuania, lithospheric thickness reaches up to 160 km. However,
the latter values are not well constrained as the confidence regions are
large. Upper-mantle viscosity is found to bracket
[2–7] × 1020 Pa s when using ICE-5G. Employing RSES much
higher values of 2 × 1021 Pa s are obtained for the southern
Baltic Sea. Further investigations should evaluate whether this ice-model version
and/or the RSL data need revision. We confirm that the lower-mantle viscosity
in Fennoscandia can only be poorly resolved.
The lithospheric structure inferred from RSES partly supports structural
features of regional and global lithosphere models based on thermal or
seismological data. While there is agreement in eastern Europe and southwest
Sweden, the structure in an area from south of Norway to northern Germany
shows large discrepancies for two of the tested lithosphere models. The
lithospheric thickness as determined with ICE-5G does not agree with the
lithosphere models. Hence, more investigations have to be undertaken to
sufficiently determine structures such as the Ringkøbing-Fyn High as seen
with seismics with the help of glacial isostatic adjustment modelling. |
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