Secular change of true polar wander over the past billion years.
Secular change of true polar wander over the past billion years.
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DOI：
10.1126/sciadv.abo2753
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发表时间：
2022-10-14
期刊：
影响因子：
13.6
通讯作者：
Xian, Hanbiao
中科院分区：
文献类型：
--
作者：
Fu, Hairuo;Zhang, Shihong;Condon, Daniel J.;Xian, Hanbiao
地球固体壳相对于自转轴的运动速率，或真正的极移，取决于地幔对流和粘度的变化。我们报告了中国南方的古地磁和地质年代学数据，这些数据限制了8.32亿至8.21亿年前的快速真极漂移速率（bb0.5°/百万年）。古地磁数据库分析表明，真极移的长期变化与跨超大陆旋回的地幔冷却和热结构有关。在超大陆合并过程中，地幔部分绝缘时，真极移率相对较低，在超大陆分裂过程中，当地幔热混合重新建立时，真极移率加速。新元古代的真极移率逐渐减小，显生宙的变化总体上较小。我们认为新元古代广泛的板块构造活动增强了地幔冷却，导致地幔对流强迫减少，地幔粘度增加，显生宙的真极漂移率降低。地幔冷却和热结构控制了真极移速率的长期变化。
The rate of movement of Earth’s solid shell relative to its spin axis, or true polar wander, depends on variations in mantle convection and viscosity. We report paleomagnetic and geochronologic data from South China that constrain the rate of rapid true polar wander (>5° per million years) between 832 million years and 821 million years ago. Analysis of the paleomagnetic database demonstrates secular change of true polar wander related to mantle cooling and thermal structure across supercontinent cycles. True polar wander rates are relatively muted with a partially insulated mantle during supercontinent assembly and accelerate as mantle thermal mixing reestablishes with supercontinent breakup. Decreasing true polar wander rate through the Neoproterozoic was succeeded by overall smaller variations in the Phanerozoic. We propose that Neoproterozoic extensive plate tectonic activities enhanced mantle cooling, giving rise to a reduction in mantle convective forcing, an increase in mantle viscosity, and a decrease in true polar wander rates into the Phanerozoic. Mantle cooling and thermal structure control secular change of true polar wander rates.
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