Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY, 14627, USA.
Geomagnetism Laboratory, University of Liverpool, Liverpool, L69 3GP, UK.
Nat Commun. 2019 Jul 29;10(1):3370. doi: 10.1038/s41467-019-11314-6.
Controversy surrounds the fixity of both hotspots and large low shear velocity provinces (LLSVPs). Paleomagnetism, plate-circuit analyses, sediment facies, geodynamic modeling, and geochemistry suggest motion of the Hawaiian plume in Earth's mantle during formation of the Emperor seamounts. Herein, we report new paleomagnetic data from the Hawaiian chain (Midway Atoll) that indicate the Hawaiian plume arrived at its current latitude by 28 Ma. A dramatic decrease in distance between Hawaiian-Emperor and Louisville chain seamounts between 63 and 52 Ma confirms a high rate of southward Hawaiian hotspot drift (~47 mm yr), and excludes true polar wander as a relevant factor. These findings further indicate that the Hawaiian-Emperor chain bend morphology was caused by hotspot motion, not plate motion. Rapid plume motion was likely produced by ridge-plume interaction and deeper influence of the Pacific LLSVP. When compared to plate circuit predictions, the Midway data suggest ~13 mm yr of African LLSVP motion since the Oligocene. LLSVP upwellings are not fixed, but also wander as they attract plumes and are shaped by deep mantle convection.
热点和大型低速剪切速度省（LLSVPs）的固定性存在争议。古地磁、板块电路分析、沉积相、地球动力学模型和地球化学表明，夏威夷地幔柱在皇帝海山形成过程中在地球地幔中移动。在此，我们报告了来自夏威夷链（中途岛环礁）的新古地磁数据，这些数据表明夏威夷地幔柱在 28 Ma 时到达了当前的纬度。63 到 52 Ma 之间夏威夷-皇帝和路易斯维尔链海山之间的距离急剧减小，证实了夏威夷热点漂移的高速率（约 47mm/yr），并且排除了真正的极移作为一个相关因素。这些发现进一步表明，夏威夷-皇帝链弯曲形态是由热点运动引起的，而不是板块运动。热点运动可能是由脊-柱相互作用和太平洋 LLSVP 的更深影响产生的。与板块电路预测相比，中途数据表明自渐新世以来非洲 LLSVP 运动约为 13mm/yr。LLSVPs 上涌不是固定的，它们也会随着吸引地幔柱而移动，并受到深部地幔对流的影响。
