Evidence for the Mesozoic endogenous activity in the northeastern part of the Fennoscandian Shield |
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| Authors: | R V Veselovskiy and A A Arzamastsev |
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| Abstract: | Paleomagnetic study of dykes and intrusions remanent in the central part of the Kola Peninsula has been carried out; the Devonian
age of these objects has been confirmed by isotopic-geochronological studies. The component analysis of the magnetization
vector in the samples has shown that there are two magnetization components in most samples. The paleomagnetic pole corresponding
to the direction of a more stable component is located in the close vicinity of the Middle Devonian segment of the apparent
polar wander path (APWP) for the East European Craton, so this enables us to estimate its age to be as old as the Devonian.
The second magnetization component was found in Devonian dykes of both northern and southern parts of the Kola Peninsula;
the paleomagnetic pole corresponding to this component is located close to the Mesozoic (Early Jurassic) part of the APWP
for the East European Craton. It is suggested that the extensive remagnetization of Devonian intrusions in the Kola Peninsula
was caused by the thermal effect of the Barents-Amerasian superplume and by the appearance of an extensive area with trap
magmatism within the modern Arctic Basin region. Discovery of a significant thermal event that covered the Fennoscandian northeast
allows us to explain the geochronological problem concerning the Mesozoic ages of particular singular zircon grains from Precambrian
rocks of the shield derived via the SHRIMP method. |
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