ANALYSIS OF NRM DIRECTIONS FROM THE ROSSELLO COMPOSITE - IMPLICATIONS FOR TECTONIC ROTATIONS OF THE CALTANISSETTA BASIN, SICILY

The paleomagnetic results of the Pliocene marine marls from the Rossello composite section [30] in the Caltanissetta basin of Sicily have been analysed to determine the amount and timing of tectonic rotations. The analysis shows that there is a consistent inclination error for the NRM component, which is removed between 500 and 600-degrees-C, which may be caused by compaction of the sediment. Differences in inclination error throughout the composite section are related to differing carbonate content, a higher carbonate content implying less compaction and smaller inclination error. Furthermore, consistent differences are found between directions of normal and reversed polarities as well as between directions of the lower and upper part of the composite section. These differences are to a large extent related to differences in carbonate content, porosity and influence of weathering. The Caltanissetta basin shows a total clockwise rotation of 34-degrees occurring since the early Pliocene. The magnetostratigraphy of the Rossello composite section shows that from the Miocene/Pliocene boundary (5.2 Ma) up to the Gilbert/Gauss boundary (3.6 Ma) there were no tectonic rotations of the Caltanissetta basin. Further, we speculate that 10-degrees of this total clockwise rotation occurred during approximately Kaena times (ca. 3.05 Ma), and that at least 24-degrees of this clockwise rotation is younger than the Gauss/Matuyama boundary (2.6 Ma).