Quantification of Pacific Plate Hotspot Tracks Since 80 Ma and the Relative Timing of Eocene Plate Tectonic Events

The motion of the Pacific plate relative to Pacific hotspots produces age-progressive chains of volcanoes. Herein new methods of analysis of seamount locations and age dates using a small number of adjustable parameters (10 per chain) are presented. Simple fits to age progressions along Pacific hotspot chains indicate 1σ age uncertainties of ~±1.0 to ±3.0 Ma. Motion between the Hawaii and Louisville hotspots differs insignificantly from zero with rates of 2±4 mm/a (=±2σ) for 0-48 Ma and 26±34 mm/a (=±2σ) for 48-80 Ma. Relative to a mean Pacific hotspot reference frame, motions of the Hawaii, Louisville, and Rurutu hotspots are also insignificant. Thus plumes underlying these Pacific hotspots are more stable in a convecting mantle than previously inferred. We find no significant difference in age between the Eocene bends of the Pacific hotspot chains. The best-fitting assumed-coeval age for the bends is 47.4±1.0 Ma (=±2σ), coincident in time with the initiation of the doubling of the spreading rate of the Pacific plate relative to the Farallon and Vancouver plates. The initiation of the Eocene slowdown of India preceded the bends and was completed after the bends. Any causal relation of this slowdown to the Hawaiian-Emperor bend remains obscure. On the other hand, initiation of subduction of the Pacific plate in the west and southwest Pacific Ocean Basin also preceded the formation of the bends, consistent with subduction initiation changing the torque on the Pacific plate such that it started moving in a more westward direction thus creating the Hawaiian-Emperor Bend.