Neogene to recent tectonic evolution of the Central Mediterranean : an integrated paleomagnetic approach

Abstract

Paleomagnetic studies of sediments from the Calabro-Peloritan block in southern Italy consequently imply a 15° clockwise rotation for the late Tortonian to middle Pleistocene sedimentary cover; but the results of older sediments are generally less consistent. Earlier paleomagnetic results of Tortonian sites from the Basilicoi section (Crotone basin, northern Calabria) suggested a major counterclockwise rotation of 97° (Scheepers, 1994b). Here, we studied the Basilicoi section in detail and we used anisotropy of the magnetic susceptibility (AMS) to reconstruct the bedding plane needed for tilt correction. This reduced the 97° counterclockwise rotation to a 25° counterclockwise rotation. The Lese section, also in northern Calabria, shows the same counterclockwise rotation in sediments with an age between 10.4 and 8.6 Ma, thus confirming the results from the corrected Basilicoi section. A comparison of the magnetostratigraphy and planktonic foraminiferal biostratigraphy with the magneto-biostratigraphic framework of the Mediterranean late Miocene allows a correlation of the Basilicoi and Lese sections to the GPTS and a timeframe for the rotation. It is concluded that the 25° counterclockwise rotation phase took place between -7.6 ± 0.1 and 8.6 Ma. We speculate that the timing of this tectonic phase is related to the opening of the Tyrrhenian Sea and the separation of Calabria from Sardinia. We compare our results with those of ODP leg 107 and we suggest an age between 8.6-7.8 Ma for the timing of the opening of the Tyrrhenian Sea.