Earliest Eocene (53 Ma) convergence in the Southwest Pacific: evidence from pre-obduction dikes in the ophiolite of New Caledonia

Uncertainty about the timing and location of the initiation of convergence in the western and south-western Pacific greatly hinders accurate plate tectonic reconstructions of subduction systems in that area. The chemistry and age of dikes intruding mantle peridotite in the ophiolite of New Caledonia infer that subduction-related magmatism began before 53Ma. These new results infer that obduction in the south-west Pacific is unrelated to the reorientation of the Pacific plate motion that occurred c. 43Ma and confirm new interpretations showing that changes in mantle flow, hotspot and plate motion may have occurred as soon as late Paleocene or early Eocene. © 2006 Blackwell Publishing Ltd.