Are the Pacific and Indo–Atlantic hotspots fixed? Testing the plate circuit through Antarctica

Abstract

It is often assumed that hotspots are fixed relative to one another and thus constitute a global reference frame for measuring absolute plate motions and true polar wander. But it has long been known that the best documented hotspot track, the Hawaiian-Emperor chain, is inconsistent with the internally coherent tracks left by the Indo-Atlantic hotspots. This inconsistency is due either to unquantified motions within the plate circuit linking the Pacific with other plates, for example, between East and West Antarctica, or relative motion between the Hawaiian-Emperor and Indo-Atlantic hotspots. Analysis of recent paleomagnetic results from Marie Byrd Land in West Antarctica confirms that there has been post-100 Ma motion between West Antarctica (Marie Byrd Land) and East Antarctica. However, incorporation of this motion into the plate circuit does not account for the Cenozoic hotspot discrepancy. Comparison of an updated inventory of Pacific and non-Pacific paleomagnetic data does not show a significant systematic discrepancy, which, along with other observations, indicates that missing plate boundaries and other errors in the plate circuit play a relatively small role in the hotspot inconsistency. We conclude that most of the apparent motion between the Hawaiian-Emperor and Indo-Atlantic hotspots is real. The best-estimate average drift rate between these sets of hotspots is approximately 25 mm=yr since 65 Ma, ignoring errors in the plate circuit and a small contribution from Cenozoic motions between East and West Antarctica.

A revised kinematic model for the relative motion between Pacific oceanic plates and North America since the Late Cretaceous

“…Considerable motion between the Pacific and Indo‐Atlantic hot spots since the Cretaceous, at rates comparable with those of relative motion between lithospheric plates, is now well documented from Pacific paleomagnetic data [e.g., Tarduno and Gee , 1995; Tarduno et al , 2003]. A similar conclusion has been reached in studies comparing the consistency of Pacific and Indo‐Atlantic hot spot tracks [e.g., Cande et al , 1995; DiVenere and Kent , 1999; Raymond et al , 2000]. Furthermore, mobility of hot spots is supported by numerical models of convective mantle flow [e.g., Steinberger et al , 2004].…”

‘Boomerang’ migratory intraplate Cenozoic volcanism, eastern Australian rift margins and the Indian-Pacific mantle boundary

“…To overcome uncertainties at this mantle boundary zone, averaged Indian-Pacific hot-spot tracks were used to provide better fits to the volcanic lines. Some inconsistencies involved post-100 Ma motion between West and East Antarctica in the plate circuits, but even allowing for this, apparent motion between the post-65 Ma hot-spot systems remains (Di Venere & Kent 1999). Accounting for spreading in the Adare Trough, western Ross Sea improves the Pacific hot-spot tracks (R. D. Muller pers.…”

Absolute plate motions constrained by shear wave splitting orientations with implications for hot spot motions and mantle flow

“…Hot‐spot‐based APM models typically assume that plumes are fixed in the lower mantle, and that hot spot tracks record lithospheric motion over the plume [ Wilson , 1963; Morgan , 1971]. However, not all plumes originate in the lower mantle [e.g., Zhao , 2001; Courtillot et al , 2003; Montelli et al , 2006; Boschi et al , 2007] or are fixed with respect to each other [e.g., Molnar and Stock , 1987; Tarduno and Gee , 1995; DiVenere and Kent , 1999; Koppers et al , 2001; O'Neill et al , 2003]. To accommodate the latter observation, newer hot‐spot‐derived APM models consider only hot spot data in the Pacific domain (e.g., HS3‐NUVEL1A) or the Indo‐Atlantic domain [e.g., Müller et al , 1993].…”