Pacific hotspots reveal a Louisville-Ontong Java Nui tectonic link.

Abstract

Volcanic hotspots are thought to form by melting in an upwelling mantle plume head followed by melting of the plume tail. Plate motion then generates an age-progressive volcanic track originating from a large igneous province to a currently active hotspot. The most voluminous large igneous province, the approximately 120-million-year-old Ontong Java Nui Plateau (OJP-Nui) in the mid-Pacific, however, lacks an obvious volcanic track. Although the Louisville hotspot track was originally proposed as a candidate, limited constraints for Pacific absolute plate and plume motion before 80 million years ago (Ma) suggest a mismatch¹. Existing Pacific models rely on age-distance data from the continuous Hawai'i-Emperor and Louisville tracks, but their tracks older than approximately 80 Ma are subducted. Elsewhere on the Pacific Plate, only discontinuous seamount tracks that formed before 80 Ma are documented^2-7. Currently, models require approximately 1,200 kilometres of latitudinal motion to link the Louisville plume to the OJP-Nui¹, but palaeolatitude estimates from about 70 Ma to today remain within error of its present location^8,9, suggesting that any substantial Louisville plume motion occurred earlier. Here, through a combination of geochemistry and geochronology^9-14, we demonstrate that Samoa and Rurutu-Arago are the longest-lived Pacific hotspots, traceable to more than 100 Ma before subducting into the Mariana Trench. These tracks better constrain plate rotation between 80 Ma and 100 Ma, allowing us to update Pacific absolute plate motion models and link the Louisville volcanic track to OJP-Nui without requiring major plume motion.