PALEOMAGNETICALLY DETERMINED ROTATIONS IN THE WESTERN SICILIAN FOLD-AND-THRUST BELT

New paleomagnetic data from the west Sicilian fold and thrust belt indicate large‐scale clockwise rotations during tectonic transport. For the platform and seamount paleogeographic units of the fold and thrust belt (Panormide and Trapanese units), there is a general consistency in the magnitude of rotation along strike, suggesting the existence of large coherent structural units. For the Panormide platform, clockwise rotations in the range of 90° to 140° relative to the underlying Iblean parautochthon are recorded along 125 km of outcrop strike. In the case of the Trapanese unit, clockwise rotations in the range of 47° to 70° relative to Iblei are recorded along about 90 km of outcrop strike. Intervening basinal paleogeographic units (Imerese and Sicanian units) show clockwise rotations of similar magnitude; although few reliable data are available from these units. Palinspastic reconstruction of the thrust belt, incorporating the rotations and arguments for the present orientation of the margins of the paleogeographic units, implies that the Panormide platform and Trapanese seamounts were originally elongated more or less north‐south relative to the present orientation of Iblei. The two units apparently coalesced to the south and were discontinuous to the north. They and their intervening basins were part of a passive continental margin which occupied a large part of the area that was subsequently rifted to form the Tyrrhenian Sea. Copyright 1990 by the American Geophysical Union.