Quantification of Pacific Plate Hotspot Tracks Since 80 Ma

Abstract

The motion of the Pacific plate relative to Pacific hotspots produces age‐progressive chains of volcanoes. Methods of analysis of volcano 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 dispersions of age dates of ≈±1.0–±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. Therefore plumes underlying these Pacific hotspots may be 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 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 collision of India with Eurasia preceded the formation of the bends and was completed after their formation. Initiation of subduction of the Pacific plate in the west and southwest Pacific Ocean Basin likely 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.

Head-to-tail plume shrinking contributes to the Hawaiian-Emperor Bend and plume zonation

“…This is in contrast to the slower drift (<4.0 cm/yr) of most other major plumes 27 in the model that best characterizes the absolute motion of Africa 3 . Even among hotspots confined within the same Pacific plate and sharing an identical plate turning history, the Hawaiian plume must maintain a relative drift rate of 5.3-5.7 cm/yr 25 to reproduce the spatial separation observed between the HEB (~60º) 27 and other coeval bends (Louisville ~25º, Rurutu ~45º) 34,35 . This suggests that the drift of the Hawaiian mantle plume is unusually rapid, whether in global or Pacific contexts.…”