Pacific Plate Motion 30-70 Ma: Seamount Geochronology in the Western Pacific and the Origin of the Hawaii-Emperor Bend

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SUMMARYOceanic hot spots leave trails of volcanoes that can be interpreted in terms of tectonic plate motion. The motion of the Pacific Plate is most prominently reflected in the Hawaiian/Emperor seamount chain with a characteristic bend at about 42 Ma. The timing of this change based on dating of rocks is almost 10 million years younger than the age calculated from marine magnetic anomalies, and it has been suggested that the Hawaiian hot spot may have moved with respect to other hot spots. The Gilbert Ridge and the Tokelau seamount chain display a similar bend at their southern terminations, and offer an opportunity to improve our accuracy of absolute Pacific Plate motion and to test for the validity of the fixed hot spot concept. This project will dredge rocks from these seamount chains and date samples by 40 Ar/39 Ar isotopic methods.