Abstract We report new Ar–Ar and U–Pb ages from ten rocks in the SW Pacific region. Our results (1) establish a northward Late Miocene Australian plate movement rate of 57 mm/a for the Lord Howe hotspot chain; (2) reinforce the previously established widespread nature of Early Miocene subduction-related volcanism in onland and nearshore northern New Zealand; (3) indicate that leucotonalite xenoliths from Raoul Island are the products of Quaternary Kermadec arc magmatism rather than being Cretaceous–Pliocene basement. A synthesis of available SW Pacific data emphasises that while there is a reasonably complete record of subduction-related volcanism from at least 23 Ma to the present day, the process of back-arc basin formation is highly episodic and asymmetric. Subduction-related arcs stabilised along the Taupo–Kermadec–Tonga arc from 2 Ma to the present, along the Taranaki-Colville-Lau trend from 17–6 Ma and along the Three Kings Ridge–Northland Plateau–Northland trend from 23–18 Ma. South of latitude 25°S, back-arc basin opening occurred during the Early Miocene and Quaternary arc volcanic episodes, but does not appear to have accompanied the 17–5 Ma volcanism.