Volcano tectonic setting of the intraplate, pliocene-holocene, newer volcanic province (southeast australia): Role of crustal fracture zones

The Pliocene-Holocene Newer Volcanic Province in Victoria, southeast Australia, is a wide volcanic field site of the most recent volcanic activity of Australia. The intraplate signature and the localization on the northern side of the Southern Ocean have been used in the past to ascribe the volcanic activity either to the presence of a mantle hot spot or to thermal anomalies inherited from the seafloor spreading that separated Australia from Antarctica during the Gondwana breakup. The spacing and distribution of groups of eruption points suggests the presence of a 32 km deep mantle thermal anomaly. Alignments of eruption points indicate a strong tectonic control on magma emplacement mainly along NW-SE Mesozoic-Cenozoic structures and along N-S Palaeozoic and E-W Late Cretaceous structures. This volcano tectonic setting relates to the interference of the left-lateral kinematics of the major N-S trending faults associated with the Tasman Fracture Zone and the extensional structures of the Otway basin. This interpretation is also coherent with stress in situ data and focal mechanisms of earthquakes (SHmax oriented N150). This interpretation enhances the role of the Tasman Fracture Zone, a major sinistral transform, on the reactivation of transtensional structures, and on triggering the magmatism of the Newer Volcanic Province.