THE UPPER AND LOWER NUNIVAK SEDIMENTARY GEOMAGNETIC TRANSITIONAL RECORDS FROM SOUTHERN SICILY

The detailed paleomagnetic records of the upper and lower Nunivak pola rity transitions have been determined from Pliocene marine marls in so uthern Sicily. Magnetites are the most important carrier of the remane nce in both records. The transitions are recorded in two components; a low temperature and a high temperature component. The two components do not represent the geomagnetic field because the changes in these co mponents take place at lithological boundaries. In addition, the direc tional changes do not completely match directional changes of the same transitions recorded in Calabria, some 250 km away. The character of the virtual geomagnetic poles paths is probably caused by smoothing of the stable directions before and after the transitions. The direction al changes as well as the smoothing mechanism can be explained by the diagenetic magnetite formation model (Van Hoof et al., 1992) in which shortly after burial, the remanence carried by newly formed secondary magnetites is superposed on the initial remanence carried by primary m agnetite.