Plate tectonic evolution of the southwest Pacific

The island arcs, ridges and continental plateaus now dispersed throughout the southwest the southwest Pacific began their plate tectonic evolution from Western Gondwanaland in the middle of the late Cretaceous. Clear evidence of seafloor spreading exists in the Tasman and western coral sea basins, separating New Zealand, New Caledonia and East Papua from Australia-Antarctica. At the end of the Paleocene and through the Eocene, significant separation of Australia and Antarctica occurred, as well as the distinct evolution of the earliest southwest Pacific island chains - Solomon and North Tonga arcs. Seafloor spreading in the south Fiji basin and probably north of New Guinea occurred through the Oligocene. The Miocene appears to be a time of relative arc and plate boundary stability. At the end of the Miocene a major arc reversal occurred between Fiji and Manus Is., and significant seafloor spreading began in the north Fiji and Bismark basins, causing major ridge separation and rotation.