Water pumping in mantle shear zones.
Water pumping in mantle shear zones.
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DOI：
10.1038/ncomms15736
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发表时间：
2017-06-08
影响因子：
16.6
通讯作者：
Pochon A
中科院分区：
文献类型：
--
作者：
Précigout J;Prigent C;Palasse L;Pochon A
水在地质作用中起着重要作用。因此，提供可能影响含水流体分布的限制对于理解水如何影响地球的地球动力学至关重要。在这里，我们表明，韧性流动施加在地幔剪切带中的富水流体循环的动态控制。根据角闪石的分布，并使用位错滑移系统作为橄榄石同构造水含量的代理，我们突出了以粒度敏感蠕变为主的细粒层周围的流体聚集。这种流体聚集与位错蠕变适应应变，局部化在富水层。我们还提供了由流体压力引起的破裂的证据，其中预计水量最高。这些结果强调长期的流体泵送归因于蠕变空化和相关的相位成核在晶粒尺寸减小。考虑到应变局部化过程中普遍存在的晶粒尺寸减小过程，我们的研究结果揭示了地壳和地幔中的多个流体储层。水在许多地质过程中起着关键作用，包括削弱地壳和地幔中的晶体。本文利用角闪石分布和橄榄石位错滑移系统，论证了韧性流体对地幔剪切带富水流体循环的动力学控制作用。
Water plays an important role in geological processes. Providing constraints on what may influence the distribution of aqueous fluids is thus crucial to understanding how water impacts Earth's geodynamics. Here we demonstrate that ductile flow exerts a dynamic control on water-rich fluid circulation in mantle shear zones. Based on amphibole distribution and using dislocation slip-systems as a proxy for syn-tectonic water content in olivine, we highlight fluid accumulation around fine-grained layers dominated by grain-size-sensitive creep. This fluid aggregation correlates with dislocation creep-accommodated strain that localizes in water-rich layers. We also give evidence of cracking induced by fluid pressure where the highest amount of water is expected. These results emphasize long-term fluid pumping attributed to creep cavitation and associated phase nucleation during grain size reduction. Considering the ubiquitous process of grain size reduction during strain localization, our findings shed light on multiple fluid reservoirs in the crust and mantle. Water plays a key role in many geological processes, including weakening crystals in the crust and mantle. Here, using amphibole distribution and olivine dislocation slip-systems, the authors show that ductile flow also has a dynamic control on water-rich fluid circulation in mantle shear zones.