Cenozoic latitudinal shift of the Hawaiian hotspot and its implications for true polar wander

Abstract

Pacific plate equatorial sediment facies provide estimates of the northward motion of the Pacific plate that are independent of paleomagnetic data and hotspot tracks. Analyses of equatorial sediment facies consistently indicate less northward motion than analyses of the dated volcanic edifices of the Hawaiian-Emperor chain. The discrepancy is largest 60–70 Ma B.P.; the 60- to 70-Ma equatorial sediment facies data agree with recent paleomagnetic results from deep-sea drilling on Suiko seamount [1] and from a northern Pacific piston core [2]. Equatorial sediment facies data and paleomagnetic data, combined with K-Ar age dates along the Emperor chain [3], indicate a position of the spin axis at 65 Ma B.P. of 82°N, 205°E in the reference frame in which the Pacific Ocean hotspots are fixed. This pole agrees well with the position of the spin axis in the reference frame in which the Atlantic Ocean hotspots and the Indian Ocean hotspots are fixed [4,5], supporting the joint hypotheses that (1) the Pacific Ocean hotspots are fixed with respect to the hotspots in other oceans, (2) the hotspots have shifted coherently with respect to the spin axis, and (3) the time average of the earth's magnetic field 65 Ma B.P. was an axial geocentric dipole. Global Neogene paleomagnetic data suggest that a shift of the mantle relative to the spin axis has been occurring during the Neogene in the same direction as the shift between 65 Ma B.P. and the present. All data are consistent with a model in which the hotspots (and by inference the mantle) have shifted with respect to the spin axis about a fixed Euler pole at a constant rate of rotation for the last 65 Ma.