Abstract The dynamics of the Earth's mantle is still poorly constrained due to the lack of understanding the transfer of matter between the upper and the lower mantle and their convective vigor. The transition zone (TZ) might play a crucial role as the interface connecting the upper to the lower mantle. Here, we examine the rheology of the main TZ minerals, wadsleyite, ringwoodite and majorite garnet based on a mineral physics approach. Using the results of lattice friction modeling and dislocation glide mobilities together with the available data on self-diffusion in the TZ minerals, we quantify their plastic deformation by diffusion and dislocation creep from theoretical plasticity models. We show that pure climb creep is expected to contribute to the plasticity of the TZ without the need of significant diffusion-related hydrolytic weakening, matching well the geophysical observations. Our model results predict that crystallographic preferred orientations (CPO) might only develop along with stress concentrations as present around cold subducting slabs which can be locally weaker than the surrounding TZ despite their lower temperatures.

中文翻译：

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穿过地幔过渡带的变形：理论矿物物理学观点

摘要 由于对上、下地幔之间物质的转移及其对流活力缺乏了解，地幔动力学仍然缺乏约束。过渡带（TZ）作为连接上地幔和下地幔的界面可能起着至关重要的作用。在这里，我们基于矿物物理学方法检查了主要 TZ 矿物、瓦兹利石、菱镁矿和主要石榴石的流变学。使用晶格摩擦建模和位错滑动迁移率的结果以及 TZ 矿物中自扩散的可用数据，我们通过理论塑性模型的扩散和位错蠕变来量化它们的塑性变形。我们表明，纯爬升蠕变预计有助于 TZ 的塑性，而无需显着的与扩散相关的水解减弱，与地球物理观测相吻合。我们的模型结果预测，结晶择优取向 (CPO) 可能只会随着冷俯冲板片周围存在的应力集中而发展，尽管它们的温度较低，但它可能比周围的 TZ 局部弱。