Anomalous Late Jurassic motion of the Pacific Plate with implications for true polar wander
Anomalous Late Jurassic motion of the Pacific Plate with implications for true polar wander
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DOI：
10.1016/j.epsl.2018.02.034
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发表时间：
2018-05-15
影响因子：
5.3
通讯作者：
Kent, Dennis, V
中科院分区：
文献类型：
--
作者：
Fu, Roger R.;Kent, Dennis, V
真极漂移（TPW）是整个地幔-地壳系统绕赤道轴的旋转，导致所有岩石圈板块的相干速度贡献。最近的候选 TPW 事件之一包括侏罗纪晚期（160-145 Ma）期间类似 30 度的旋转。然而，现有关于这一事件的古地磁记录仅来自大陆，其面积不到地球表面积的 50%，可能无法反映整个地幔-地壳系统的运动。来自太平洋盆地的额外古位置信息将显着增强地球表面的覆盖范围，并允许对 TPW 的发生进行更严格的测试。我们对来自海洋钻探计划 (ODP) 801B 站点的岩心样本进行古地磁分析，这些岩心样本取自最古老的太平洋地壳，以确定其晚侏罗世和早白垩世 (167-133 Ma) 期间的古纬度。我们发现太平洋板块经历了0.49度-0.74度My(-1)的稳定向南漂移，除了启莫里阶和提通阶之间的一段时间（157-147Ma）外，太平洋板块经历了1.45度+/-0.76度My(-1)（1西格玛）向北运动。该轨迹表明，太平洋盆地板块在160-145 Ma区间参与了与大陆岩石圈相同的大幅度（接近30度）的旋转。地球表面大部分区域的这种相干运动有力地支持了TPW的发生，表明俯冲板片和上升的地幔柱的组合足以显着扰动晚侏罗世的地球惯性张量。 (C) 2018 Elsevier B.V. 保留所有权利。
True polar wander, or TPW, is the rotation of the entire mantle-crust system about an equatorial axis that results in a coherent velocity contribution for all lithospheric plates. One of the most recent candidate TPW events consists of a similar to 30 degrees rotation during Late Jurassic time (160-145 Ma). However, existing paleomagnetic documentation of this event derives exclusively from continents, which compose less than 50% of the Earth's surface area and may not reflect motion of the entire mantle-crust system. Additional paleopositional information from the Pacific Basin would significantly enhance coverage of the Earth's surface and allow more rigorous testing for the occurrence of TPW. We perform paleomagnetic analyses on core samples from Ocean Drilling Program (ODP) Site 801B, which were taken from the oldest available Pacific crust, to determine its paleolatitude during the Late Jurassic and Early Cretaceous (167-133 Ma). We find that the Pacific Plate underwent a steady southward drift of 0.49 degrees-0.74 degrees My(-1) except for an interval between Kimmeridgian and Tithonian time (157-147 Ma), during which it underwent northward motion at 1.45 degrees +/- 0.76 degrees My(-1) (1 sigma). This trajectory indicates that the plates of the Pacific Basin participated in the same large-amplitude (similar to 30 degrees) rotation as continental lithosphere in the 160-145 Ma interval. Such coherent motion of a large majority of the Earth's surface strongly supports the occurrence of TPW, suggesting that a combination of subducting slabs and rising mantle plumes was sufficient to significantly perturb the Earth's inertia tensor in the Late Jurassic. (C) 2018 Elsevier B.V. All rights reserved.