Large-scale motion between Pacific and Atlantic hotspots

Abstract

STUDIES of true polar wander (TPW), the rotation of the solid Earth with respect to the spin axis1, have suggested that there has been 10–15° of relative motion over the past 130 Myr (refs 2–4). In such studies, the orientation of the spin axis is recovered from continental palaeomagnetic poles (corrected for relative plate motions), and compared with a deep-mantle reference frame defined by hotspot locations. But deducing relative plate motions becomes increasingly difficult for older (Mesozoic) time periods, hindering tests of TPW on timescales comparable to those of large-scale mantle convection; moreover, the assumption of hotspot fixity is controversial5,6. We examine here a more direct approach7,8, using palaeolatitudes derived from Pacific guyots. Contrary to predictions from TPW models, these data suggest only minor latitudinal shifts of Pacific hotspots during the Cretaceous period. Instead of TPW, relative motion between the Atlantic and Pacific hotspot groups9 is required at a velocity of approximately 30 mm yr−1, more than 50% larger than previously proposed5.