Ar-40/Ar-39 dating and paleomagnetism of the Miocene volcanic succession of Monte Furru (western Sardinia): Implications for the rotation history of the Corsica-Sardinia microplate

Although it is widely acknowledged that the Corsica-Sardinia microplate rot ated counterclockwise with respect to Europe during Oligocene-Miocene time, the precise timing of this event has yet to be determined. We have measure d the age and degree of rotation of a single 'tie-point' in the rotation hi story of the microplate. Biotite and sanidine Ar-40/Ar-39 age determination s of the 200m-thick Monte Furru volcanic succession indicates that most of the volcanic pile accumulated within less than 200 ky. The paleomagnetic po le obtained for the 12 volcanic flow units comprising this succession indic ates that by 18.2 Ma Sardinia remained 13 degrees shy of its final rotation angle. These results demonstrate that the movement of the Corsica-Sardinia block and the opening of the liguro-provencal basin terminated later than previously estimated based on paleomagnetic and geochronologic studies of S ardinian volcanic rocks, in agreement with paleomagnetic data from Sardinia n sediments.