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| Titel |
Density structure of the Scandes lithosphere from surface to depth |
| VerfasserIn |
Jörg Ebbing, Odleiv Olesen, Torleif Lauritsen |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250036703
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| Zusammenfassung |
| In our study, we demonstrate the importance of the near-surface density distribution (upper 5
km of the crust) in modelling of the density structure of the lithosphere. The Bouguer
anomaly over the Norwegian mountains (Scandes) shows a gravity low along the entire
Scandes mountain belt, which is indicating, at least partly, isostatic compensation. In contrast
to this observation seismological studies have not imaged a pronounced crustal root along the
entire mountain range, and for the southern Scandes a low-density upper mantle has been
introduced by various authors to explain the gravity low and to achieve isostatic
equlibrium. In a previous model we showed that the lower crust plays an important role in
achieving isostatic equilibrium, but for the southern Scandes a pattern of +/-20 mGal of
the gravity low remained unexplained, and appeared to be correlating to surface
geology. Here, we make use of a newly established surface density distribution
for mainland Norway. Using the variable surface density distribution instead of a
constant density for Bouguer correction reduces parts of the remaining gravity
residuals due to the variation of surface density (2600-2900 kg/m3). The Jotun
Nappe within the Caledonian Orogen in central southern Norway consists mainly
of mafic high-density Precambrian rocks. Extension of the surface geology and
measured density to 4 km depth produces a gravity signal that exceeds 40 mGal.
Consideration of the gravity effect from the Caledonian nappes gives a gravity signal that
more clearly shows a possible mantle component below the Southern Scandes. |
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