Fast Paleogene Motion of the Pacific Hotspots From Revised Global Plate Circuit Constraints

Major improvements in Late Cretaceous-early Tertiary Pacific-Antarctica plate reconstructions, and new East-West Antarctica rotations, allow a more defmitive test of the relative motion between hotspots using global plate circuit reconstructions with quantitative uncertainties. The hotspot reconstructions, using an updated Pacific-hotspot kinematic model, display significant misfits of observed and reconstructed hotspot tracks in the Pacific and Indian Oceans. The misfits imply motions of 5-80 mm/yr throughout the Cenozoic between the African-Indian hotspot group and the Hawaiian hotspot. Previously recognized misfits between reconstructed Pacific plate paleomagnetic poles and those of other plates might be accounted for within the age uncertainty of the paleomagnetic poles, and non-dipole field contributions. We conclude that the derived motion of the Hawaiian hotspot relative to the Indo-Atlantic hotspots between 61 Ma and present is a robust result. Thus, the Pacific hotspot referenc·e frame cannot be considered as fixed relative to the deep mantle. The bend in the Hawaiian-Emperor Seamount chain at 43 Ma resulted from a speedup in the absolute motion of the Pacific plate in a westward direction during a period of southward migration of the hotspot. The relationship between the hotspot motion and plate motion at Hawaii suggests two possible scenarios: an entrainment of the volcanic sources in the asthenosphere beneath the rapidly moving plate while the hotspot source drifted in a plate-driven counterflow deeper within the mantle, or drift of the hotspot source which was independent of the plate motion, but responded to common forces, producing synchronous changes in hotspot and plate motion during the early Tertiary.