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Plate tectonics and mantle controls on plume dynamics
Earth and Planetary Science Letters ( IF 5.3 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.epsl.2020.116439
Maëlis Arnould , Nicolas Coltice , Nicolas Flament , Claire Mallard

Abstract Mantle plumes provide valuable information about whole-mantle convection: they originate at the core-mantle boundary, cross Earth's mantle and interact with the lithosphere. For instance, it has been proposed that the mobility/stability of plumes depends on plume intrinsic properties, on how slabs interact with the basal boundary layer, on mantle flow, or on their proximity to mid-ocean ridges. Here, we use 3D-spherical models of mantle convection generating self-consistent plate-like behaviour to investigate the mechanisms linking tectonics and mantle convection to plume dynamics. Our models produce fully-dynamic mantle plumes that rise vertically with deflection 10 ° and present excess temperatures, rising speeds, buoyancy and heat fluxes comparable to observations. In the absence of plate tectonics, plumes are stable and their lifetime exceeds hundreds of million years. With plate tectonics, plumes are more mobile, and we identify four physical mechanisms controlling their stability. 1/ Fixed plumes are located at saddle points of basal mantle flow. 2/ Plumes moving at speeds between 0.5-1 cm yr−1 are slowly entrained by passive mantle flow. 3/ Fast plume motions between 2-5 cm yr−1 lasting several tens of million years are caused by slab push. 4/ Plumes occasionally drift at speeds >5 cm yr−1 over 25%, which suggests that fixed hotspot reference frames can be defined from carefully selected hotspot tracks.

中文翻译:

羽流动力学的板块构造和地幔控制

摘要 地幔柱提供了关于整个地幔对流的宝贵信息:它们起源于地核-地幔边界,穿过地球地幔并与岩石圈相互作用。例如,有人提出羽流的流动性/稳定性取决于羽流的内在特性、板片如何与基底边界层相互作用、地幔流或它们与大洋中脊的接近程度。在这里,我们使用产生自洽板状行为的地幔对流的 3D 球形模型来研究将构造和地幔对流与羽流动力学联系起来的机制。我们的模型产生全动态地幔羽流,垂直上升,偏转 10°,并呈现出与观测结果相当的温度、上升速度、浮力和热通量。在没有板块构造的情况下,羽流稳定,寿命超过数亿年。在板块构造中,羽流更具流动性,我们确定了四种控制其稳定性的物理机制。1/ 固定羽流位于基底地幔流的鞍点。2/ 以 0.5-1 cm yr−1 之间的速度移动的羽流被被动地幔流缓慢带走。3/ 持续数千万年的 2-5 cm yr-1 之间的快速羽流运动是由板块推动引起的。4/ 羽流偶尔会以 >5 cm yr−1 的速度漂移超过 25%,这表明可以从精心选择的热点轨迹中定义固定热点参考系。2/ 以 0.5-1 cm yr−1 之间的速度移动的羽流被被动地幔流缓慢带走。3/ 持续数千万年的 2-5 cm yr-1 之间的快速羽流运动是由板块推动引起的。4/ 羽流偶尔会以 >5 cm yr−1 的速度漂移超过 25%,这表明可以从精心选择的热点轨迹中定义固定热点参考系。2/ 以 0.5-1 cm yr−1 之间的速度移动的羽流被被动地幔流缓慢带走。3/ 持续数千万年的 2-5 cm yr-1 之间的快速羽流运动是由板块推动引起的。4/ 羽流偶尔会以 >5 cm yr−1 的速度漂移超过 25%,这表明可以从精心选择的热点轨迹中定义固定热点参考系。
更新日期:2020-10-01
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