Common occurrence of the miocene calc-alkaline volcanism along the western Corsican margin (Margo Cruise)

During the MARCO cruise, systematic exploration along the western and northern Corsican margins was carried out by dredging. The compositions of the dredged rocks range from basalt to amphibole-biotite bearing andesite with a broad calc-alkaline character. A Miocene age has been obtained for the amphibole-biotite andesite sample DR02 both by 40Ar-39Ar dating on hornblende (16.0±0.4 My) and using fission-track method on apatite (17.2 ± 0.8 My). The south western Corsican volcanic zone represents the direct extension of the Miocene Sardinian graben volcanism north of 42 deg 00 N. It could either be synchronous with or post-date the oceanic opening event. Such an arc volcanism probably results from the subduction to the north of the Liguro-Piemont ocean beneath Europe, the Provencal-Ligurian basin being in back-arc position with respect to the studied volcanic centres. (authors)