High Temperature Deformation of Lower Mantle Minerals Phases in the Diamond Anvil Cell

金刚石砧座中下地幔矿物相的高温变形

• 批准号: 1344579
• 负责人: Lowell Miyagi
• 金额: $ 30.5万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1344579&HistoricalAwards=false
• 关键词: Temperature; Deformation; Lower; Mantle; Minerals

Seismic anisotropy is observed in many regions of the deep Earth and is believed to be due to texturing of mantle rock as a result of solid state convection. Thus observations of seismic anisotropy can be used to interpret the dynamic processes occurring in the Earth's interior. However, this requires that the relationship between deformation geometry, texture development and seismic anisotropy are well understood for the appropriate mineral phases. In the upper mantle where deformation mechanisms are well understood, interpretation of seismic anisotropy in terms of mantle flow has been highly successful. However, in deeper parts of the Earth, little is known about the deformation mechanisms of the major mineral phases such as MgSiO3 perovskite and post-perovskite. This is largely due to the fact that pressures needed to stabilize these phases are beyond the range of conventional deformation devices. The diamond anvil cell combined with radial diffraction technique can be used to study deformation and texture development in these phases, but until recently these experiments could only be performed at room temperature. Since textures can be affected by temperature, it is problematic to extrapolate these results to the deep Earth where temperatures are high. Recent developments now allow diamond anvil cell deformation experiments to be performed at lower mantle pressures and temperatures. This project will use this new technique to study texture development and deformation mechanisms in lower mantle mineral phases at high pressure and temperature conditions.The significance of this project is that it will establish an experimental basis for linking seismic observations to deformation structure in the very deep Earth. This will lay the groundwork to allow the use of seismic data to map flow patterns in the lowermost mantle. Understanding the dynamics at the base of the mantle will provide new insight into the mechanics and geometry of mantle convection. A better understanding of mantle convection, in turn, has implications for plate tectonics, mantle geochemistry, and thermal history of the Earth. In addition, new technical developments resulting from this project will be available to general users at the Advanced Light Source at Lawrence Berkeley National Laboratory and thus will serve the broader scientific community. Furthermore, the capability to perform high pressure and high temperature deformation studies has application beyond the field of geophysics and will also advance knowledge of material science at extreme conditions.

地震各向异性在地球深处的许多地区都能观察到，并被认为是由于固体对流导致的地幔岩石的纹理。因此，地震各向异性观测可以用来解释地球内部发生的动态过程。然而，这需要对适当的矿物相很好地理解变形几何、结构发育和地震各向异性之间的关系。在了解变形机制的上地幔中，从地幔流动的角度解释地震各向异性是非常成功的。然而，在地球更深的地方，人们对主要矿物相如镁硅钙钛矿和后钙钛矿的变形机制知之甚少。这在很大程度上是因为稳定这些相所需的压力超出了传统变形装置的范围。金刚石压腔结合径向衍射技术可以用来研究这些相的变形和织构发展，但直到最近，这些实验还只能在室温下进行。由于纹理可能会受到温度的影响，因此将这些结果外推到温度较高的地球深处是有问题的。最近的发展现在允许在较低的地幔压力和温度下进行钻石顶锤单元变形实验。本项目将利用这一新技术研究高压高温条件下下地幔矿物相的结构发育和变形机制，其意义在于它将为将地震观测与地球深部变形结构联系起来奠定实验基础。这将为利用地震数据绘制地幔最下部的流动模式奠定基础。了解地幔底部的动力学将为地幔对流的力学和几何学提供新的见解。反过来，对地幔对流的更好理解又对板块构造、地幔地球化学和地球热史具有重要意义。此外，劳伦斯伯克利国家实验室的高级光源中心的普通用户将可利用这一项目产生的新技术发展，从而为更广泛的科学界服务。此外，进行高压和高温变形研究的能力不仅适用于地球物理领域，还将在极端条件下促进材料科学的知识。

项目成果

Elasto-viscoplastic self consistent modeling of the ambient temperature plastic behavior of periclase deformed up to 5.4 GPa

对变形高达 5.4 GPa 的方镁石的环境温度塑性行为进行弹粘塑性自洽建模

• DOI: 10.1063/1.4999951
• 发表时间: 2017
• 期刊: Journal of Applied Physics
• 影响因子: 3.2
• 作者: Lin, F.;Hilairet, N.;Raterron, P.;Addad, A.;Immoor, J.;Marquardt, H.;Tomé, C. N.;Miyagi, L.;Merkel, S.
• 通讯作者: Merkel, S.