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

为了了解流变性质(如660 km深度的粘性差)在地球深部地幔物质行为中的作用，在高压和高温变形实验的基础上，进行了现场观测，研究了地幔矿物的流变性。论证了粒度敏感蠕变和位错蠕变在上地幔橄榄石变形、地幔过渡带中水的显著弱化中的重要性，以及660 km深度洋壳分离的可能性，这是由于环流石和马来石化之间的低粘度反差。

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.