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2008-03-13
Palaeomagnetic investigations of sediments cores from Axios zone (N. Greece): implications of low inclinations in the Aegean
E. Aidona
aidona@geo.auth.gr
D. Kondopoulou
R. Scholger
A. Georgakopoulos
A. Vafeidis
Dept. of Geophysics, School of Geology, Univ. of Thessaloniki, Greece
Paleomagnetic Laboratory, Institute of Geophysics - University of Leoben, Austria
Dept. of Mineralogy-Petrology-Economic Geology, School of Geology, Univ. of Thessaloniki, Greece
Department of Mineral Resources Engineering, Technical University of Crete, Chania, Greece
Sediment cores from 13 deep boreholes (1–4.1 km) distributed within Axios
zone in Northern Greece have been studied by means of palaeomagnetism. Both
low field magnetic susceptibility and intensity of the natural remanent
magnetization (NRM) indicate rather weakly magnetised materials. A set of
390 samples have been subjected to thermal and alternative field
demagnetization. Isothermal remanent magnetization (IRM) acquisition curves
and thermomagnetic analysis suggest the dominance of magnetite. Thin
sections from 30 selected samples were studied in order to more precisely
characterise their magnetic mineralogy. This investigation also reveals the
presence of magnetite and pyrite in framboidal form. An attempt to re-orient
some of the samples was partially successful by using the viscous component
and the anisotropy method. These techniques were applied in order to correct
the palaeomagnetic directions due to the orientation ambiguity of the core
samples. The corrected mean direction converges towards an eastward value,
in agreement with the overall pattern of the onshore results from previous
investigations in the study area.
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Finally, the observed inclinations of characteristic remanences in these
rocks are much lower than the expected ones but converge with those obtained
from formations on land.
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