Constraints on Lower Mantle Viscosity from Diffusion Experiments on MgSiO3 Perovskite and MgO Periclase

0074189 Van Orman这是一个研究高压（23 Gpa）下MgSiO3钙钛矿和MgO方镁石中扩散质量输运的项目。 这项研究的目的是把严格的实验条件下的下地幔的温度和压力条件下，这些重要的高压相的塑性流变学。 钙长石和方镁石是下地幔中含量最丰富的矿物，它们的塑性流动特性控制着670 km以下地幔的粘度。 这将是可能的，使用本实验研究的结果，直接估计的钙钛矿方镁石下地幔的粘度变形扩散蠕变，以及温度，压力和粒度的粘度的依赖性。 因此，这项研究将为地幔粘度分层的地球物理模型提供急需的约束，预计这样做将大大提高我们对地球深部动力学的理解。

0074189Van OrmanThis is a project to investigate diffusional mass transport in MgSiO3 perovskite and MgO periclase under high pressure (23 Gpa). The study is aimed at placing rigorous experimental constraints on the plastic rheologies of these important high-pressure phases under temperature and pressure conditions of the lower mantle. Perovskite and periclase are generally agreed to be the most abundant minerals in the lower mantle, and their plastic flow properties are thus expected to control the viscosity of the mantle below 670 km. It will be possible using the results of this experimental investigation to directly estimate the viscosity of a perovskite-periclase lower mantle deforming by diffusion creep, as well as the dependence of the viscosity on temperature, pressure, and grain size. The study will thus provide a much-needed constraint on geophysical models of viscosity stratification in the mantle, and in doing so is expected to significantly improve our understanding of the dynamics of the Earth's deep interior.