Rheological structure of the 660 km discontinuity in the Earth's mantle

为了了解流变特性（如660 km深度的粘度对比）在地球深部地幔物质行为中的作用，基于现场观测的高压和高温变形实验研究了地幔矿物的流变特性。我们证明了晶粒尺寸敏感蠕变和位错蠕变在上地幔橄榄石变形中的重要性，在地幔过渡带中wadsleite的明显水弱化作用，以及由于环伍德岩和多数岩之间的低粘度对比，在660 km深度附近海洋地壳不太可能分离。

To understand a role of rheological properties (such as viscosity contrast at 660 km depth) in material behaviors in the Earth's deep mantle, the rheology of mantle minerals were studied based on high-pressure and high-temperature deformation experiments with in situ observation. We demonstrated the importance of grain-size-sensitive creeps, as well as dislocation creep, in deformation of the upper mantle olivine, the significant water-weakening of wadsleyite in the mantle transition zone, and that separation of oceanic crust near 660 km depth is unlikely due to low viscosity contrast between ringwoodite and majorite.