T. P. O’Kane is grateful for the support of an Australian Postgraduate Award provided by the Australian Government. Research support was provided Australian Research Council Discovery Grant DP0877274 “Tectonic mode switches and the nature of orogenesis” and by AngloGold Ashanti Australia Ltd. We are grateful to Christian Vérard for an extensive review and Stephen Johnston for insightful observations, all of which helped us improve the manuscript.