EarthRef.org Reference Database (ERR) -- Koppers et al. 2001

Hotspots and their associated intra-plate volcanism producing seamount trails have become an accepted fact in geology from a conceptual theory. The azimuths and age progressions of these seamount trails provide the only means to determine absolute plate motions with respect to an independent reference frame of 'fixed' hotspots. However, the presumed fixity of hotspots is in disagreement with recent paleomagnetic studies and global-circuit plate reconstructions for the Hawaiian-Emperor seamount trail. In this study, we provide independent evidence suggesting that hotspots are not fixed relative to each other. We use a straightforward test that compares the observed Ar-40/Ar-39 age progressions along Pacific seamount trails (0-140 Myr) with the Pacific plate velocities as predicted by their poles of plate rotation (i.e. Euler poles), In most of these comparisons, the age progressions were found incompatible with published Euler poles, or with a new set of Euler poles as derived in this study using discrete seamount locations digitized from the bathymetry maps of Smith and Sandwell [EOS 77 (1996) 315; Science 277 (1997) 1956-1921]. We conclude that the relative motion between hotspots may be required to reconcile the observed age progressions with the predicted plate velocities from their modeled Euler poles. On average, the Pacific hotspots may show motion at 10-60 mm/yr over the last 100 Myr, partly attributed to individual hotspot motion, whereas systematic motion of these hotspots (due to true polar wander) may account for the remainder. (C) 2001 Elsevier Science B.V. All rights reserved.