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

Abstract

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