Paleomagnetism of the Plio-Pleistocene continental sediments from the north -eastern edge of the Fucino basin (Central Italy)

摘要

The paleomagnetism of the Plio-Pleistocene continental sediments cropping out at the north-eastern edge of the Fucino extensionaI basin (Italy, Central Apennines) was investigated. The area is characterized by strong neo-tectonic activity and the original purpose was to investigate possibIe verticaI axis rotations in Plio-Pleisto- cene sediments, in order to improve the understanding of the recent geodynamic processes. Scarcity of suit- able outcrops limited sampling at 8 sites (83 specimens) from the north-eastern edge of the basin, in clay-rich intervals beIonging to two different sedimentary cycIes. The paleomagnetic resuIts pointed out a peculiar mag- netic behaviour common to the whole set of studied samples. The Natural Remanent Magnetization (NRM) is dominated by a vigcous normal component acquired under the influence of the present geomagnetic field, stable only below 200°C. Another (reverse) very weak component, stable at higher temperatures (up to 400°C), is present in most of the samples. This component can be precisely isolated for only 7 specimens from 3 different sites and therefore the information gained is not statistically sufficient for any tectonic reconstruction. Rock magnetism analyses showed a variable magnetic mineralogy j but the NRM carriers are not well represented in the artificial remanences produced in the laboratory. Results suggest that the natural viscous remanence is most likeIy carried by coarse multi-domain magnetite.