About 210 samples of rocks of late Early Jurassic to early Tertiary age from 37 sites in the Umbrian carbonate sequence in the Northern Apennines were investigated paleomagnetically. Special attention was paid to the Scaglia Formation of Cenomanian to middle Eocene age, and three well-correlated sections were studied in detail. Accurate relative ages were determined from the well-preserved planktonic foraminiferal faunas.
Paleomagnetic directions of Toarcian-Aalenian to late Aptian sites group fairly well, which implies the absence of major rotational and latitudinal movements of the sampling area during that interval. An only minor phase of movement at about Tithonian time resulted in a counterclockwise rotation over approximately 10°. Late Aptian to late Cenomanian directions indicate a southward movement over 10° of latitude; this was followed by a 30° counterclockwise rotation during Turonian, Coniacian, and Santonian time, and in addition, a northward movement over 10° of latitude during Santonian and Campanian time. Maastrichtian to early Eocene data group reasonably well but also deviate from the present local field direction; this indicates a further 25° counterclockwise rotation and an additional northward movement over more than 10° post–early Eocene time.
We suggest that the data presented here from the Northern Apennines are representative for the general pattern of movements of the Italian Peninsula.
These paleomagnetically deduced movements conform during at least late Early Jurassic to early Tertiary time with the movements of the African plate as established from sea-floor spreading and paleomagnetic data. At the same time, however, the paleomagnetic results indicate that this coupled motion of the Italian Peninsula and the African continent did not persist until the present: a post–early Eocene 25° counterclockwise rotation of the Italian Peninsula must have occurred relative to Africa.
Our data are compared with available paleomagnetic data from the western Mediterranean area. Their relation to the structural evolution of the areas concerned is discussed.