Strong plates enhance mantle mixing in early Earth.
Strong plates enhance mantle mixing in early Earth.
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DOI：
10.1038/s41467-018-05194-5
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发表时间：
2018-07-13
影响因子：
16.6
通讯作者：
Goes S
中科院分区：
文献类型：
--
作者：
Agrusta R;van Hunen J;Goes S
在今天的地球上，一些俯冲板块（板块）在约670 km深度的上下地幔边界上方变平，而另一些板块（板块）则穿过，表明一种介于层状和全地幔对流之间的模式。先前的模型预测，在地球早期温度高几百度的时候，由于主要的板块停滞，对流可能更分层。在自一致的数值模型中，板具有类似板的流变性，坚固的板和移动的板边界有利于老板的停滞和年轻板的渗透，正如今天观察到的那样。在这里，我们表明，这样的模型预测，当软流圈变弱、板块密度和强度下降导致俯冲几乎没有海沟退缩时，板块在较热的地球上更容易渗透到下地幔。因此，过去地幔中的热量和物质传输效率更高（而不是更低），这与地球的热演化更吻合。俯冲板块既可以直接侵彻下地幔，也可以在地幔过渡带中变平，但过去的板块动力学尚不清楚。在这里，作者利用俯冲模型预测，早期地球温度较高可能更有利于下地幔板块的渗透。
In the present-day Earth, some subducting plates (slabs) are flattening above the upper–lower mantle boundary at ~670 km depth, whereas others go through, indicating a mode between layered and whole-mantle convection. Previous models predicted that in a few hundred degree hotter early Earth, convection was likely more layered due to dominant slab stagnation. In self-consistent numerical models where slabs have a plate-like rheology, strong slabs and mobile plate boundaries favour stagnation for old and penetration for young slabs, as observed today. Here we show that such models predict slabs would have penetrated into the lower mantle more easily in a hotter Earth, when a weaker asthenosphere and decreased plate density and strength resulted in subduction almost without trench retreat. Thus, heat and material transport in the Earth’s mantle was more (rather than less) efficient in the past, which better matches the thermal evolution of the Earth. The subducting plates can either penetrate straight into the lower mantle or flatten in the mantle transition zone, yet slab dynamics in the past remains unclear. Here, using subduction models, the authors predict that a hotter early Earth was probably more favourable to lower mantle slab penetration.
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影响因子：
5.3
作者：
Agrusta, Roberto;Goes, Saskia;van Hunen, Jeroen
通讯作者：
van Hunen, Jeroen
影响因子：
5.3
作者：
Capitanio, F. A.;Morra, G.;Goes, S.
通讯作者：
Goes, S.
影响因子：
2.8
作者：
Conrad, CP;Hager, BH
通讯作者：
Hager, BH
影响因子：
5.3
作者：
DAVIES, GF
通讯作者：
DAVIES, GF
影响因子：
--
作者：
HAGER, BH
通讯作者：
HAGER, BH