A rapid burst in hotspot motion through the interaction of tectonics and deep mantle flow

• Published in: Nature (London) 2016-05, Vol.533 (7602), p.239-242
• Main Authors: Hassan, Rakib, Müller, R. Dietmar, Gurnis, Michael, Williams, Simon E., Flament, Nicolas
• Format: Article
• Language: English
• Subjects: 704/2151/210; 704/2151/562; 704/445/210; Deformation; Earth; Earth mantle; Geology; Humanities and Social Sciences; letter; Lower mantle; Mantle; Mathematical models; multidisciplinary; Observations; Oceans; Paleomagnetism; Plate tectonics; Plumes; Science; Tectonics; Tectonics (Geology); Volcanic hotspots
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature17422

Models of thermochemical convection reveal flow patterns in the deep lower mantle under the north Pacific since 100 million years ago that explain how the enigmatic bend in the Hawaiian–Emperor hotspot track arose. Plate-mantle dynamics at a mantle plume Rakib Hassan and co-authors present palaeogeographically constrained numerical models of thermochemical mantle convection and find that flow in the deep lower mantle under the north Pacific ocean was anomalously vigorous between 100 million years ago and 50 million years ago as a consequence of long-lasting subduction systems. Deep flow in the lower mantle and plume trajectories found in these models show that the enigmatic sharp bend in the Hawaiian–Emperor hotspot track could have naturally arisen through the interplay of plume tilt and the lateral advection of plume sources. Volcanic hotspot tracks featuring linear progressions in the age of volcanism are typical surface expressions of plate tectonic movement on top of narrow plumes of hot material within Earth’s mantle 1 . Seismic imaging reveals that these plumes can be of deep origin 2 —probably rooted on thermochemical structures in the lower mantle 3 , 4 , 5 , 6 . Although palaeomagnetic and radiometric age data suggest that mantle flow can advect plume conduits laterally 7 , 8 , the flow dynamics underlying the formation of the sharp bend occurring only in the Hawaiian–Emperor hotspot track in the Pacific Ocean remains enigmatic. Here we present palaeogeographically constrained numerical models of thermochemical convection and demonstrate that flow in the deep lower mantle under the north Pacific was anomalously vigorous between 100 million years ago and 50 million years ago as a consequence of long-lasting subduction systems, unlike those in the south Pacific. These models show a sharp bend in the Hawaiian–Emperor hotspot track arising from the interplay of plume tilt and the lateral advection of plume sources. The different trajectories of the Hawaiian and Louisville hotspot tracks arise from asymmetric deformation of thermochemical structures under the Pacific between 100 million years ago and 50 million years ago. This asymmetric deformation waned just before the Hawaiian–Emperor bend developed, owing to flow in the deepest lower mantle associated with slab descent in the north and south Pacific.