Reconciling the Cretaceous breakup and demise of the Phoenix Plate with East Gondwana orogenesis in New Zealand

Following hundreds of millions of years of subduction, the Pacific Plate started to share a mid-ocean ridge connection with Antarctica during a Late Cretaceous south Pacific plate reorganization. This reorganization was associated with the end of subduction of the remnants of the Phoenix Plate, which had occupied large parts of the southern paleo-Pacific/Panthalassa Ocean during the Mesozoic. Interpretations based on overriding plate geology suggest that subduction ended at 105-100 Ma age, whereas plate reconstructions have suggested ongoing convergence until 86 Ma. In this study we present a new plate reconstruction and identify ways to reconcile the outcome with geological records of subduction along the Gondwana margin of New Zealand and New Caledonia. We re-evaluate the plate kinematic evolution of the Phoenix Plate from 150 Ma onward, form its original spreading relative to the Pacific Plate, through its break-up during emplacement of the Ontong Java Nui Large Igneous Province, through the arrest of subduction below East Gondwana, to today. Our reconstruction demonstrates that convergence continued between the Pacific Plate and Zealandia after 100 Ma, until 90-85 Ma. The end of subduction below most of East Gondwana resulted from a change in relative plate motion between the Pacific Plate and the East Gondwana from westerly to northerly, of which the cause remains unknown. In addition, the arrival of the Hikurangi Plateau in the subduction zone may have caused the local cessation of subduction of the Hikurangi Plate, but this occurred independent from, and did not cause, the change in Pacific Plate motion.