Dynamics of the abrupt change in Pacific Plate motion around 50 million years ago
Dynamics of the abrupt change in Pacific Plate motion around 50 million years ago
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DOI：
10.1038/s41561-021-00862-6
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发表时间：
2021-12
影响因子：
18.3
通讯作者：
Jiashun Hu;M. Gurnis;J. Rudi;G. Stadler;R. Müller
中科院分区：
文献类型：
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作者：
Jiashun Hu;M. Gurnis;J. Rudi;G. Stadler;R. Müller
板块构造和地幔对流的剧烈变化发生在50 Ma左右，突出的夏威夷-皇帝弯曲就是例证。太平洋板块运动的突然变化和地幔柱动力学的变化都被认为是造成夏威夷-皇帝弯曲的原因，但围绕这两种机制的相对贡献存在争议。在这里，我们建立运动板块重建和高分辨率的全球动力学模型，以量化太平洋板块运动的变化量。我们发现Izanagi板块俯冲，随后Izanagi太平洋海岭的消亡和Izu-Bonin-Mariana俯冲启动单独，是不能引起板块运动的突然变化，挑战传统的假设，太平洋板块运动的变化机制。相反，来自北方太平洋克罗诺茨基洋内俯冲的古新世板块拉力对太平洋板块施加了一个向北的拉力，而其始新世的消亡导致板块运动突然发生30-35°的变化，约占夏威夷-皇帝弯曲的一半。我们认为，太平洋板块运动的变化和热点漂移，由于羽动力学可能有几乎相等的夏威夷皇帝弯曲的形成。这种情况是一致的全球板块电路，古地磁数据和地球动力学模型的现有限制。
A drastic change in plate tectonics and mantle convection occurred around 50 Ma as exemplified by the prominent Hawaiian–Emperor Bend. Both an abrupt Pacific Plate motion change and a change in mantle plume dynamics have been proposed to account for the Hawaiian–Emperor Bend, but debates surround the relative contribution of the two mechanisms. Here we build kinematic plate reconstructions and high-resolution global dynamic models to quantify the amount of Pacific Plate motion change. We find Izanagi Plate subduction, followed by demise of the Izanagi–Pacific Ridge and Izu–Bonin–Mariana subduction initiation alone, is incapable of causing a sudden change in plate motion, challenging the conventional hypothesis on the mechanisms of Pacific Plate motion change. Instead, Palaeocene slab pull from Kronotsky intraoceanic subduction in the northern Pacific exerts a northward pull on the Pacific Plate, while its Eocene demise leads to a sudden 30–35° change in plate motion, accounting for about half of the Hawaiian–Emperor Bend. We suggest the Pacific Plate motion change and hotspot drift due to plume dynamics could have contributed nearly equally to the formation of the Hawaiian–Emperor Bend. Such a scenario is consistent with available constraints from global plate circuits, palaeomagnetic data and geodynamic models.