Plastic Deformation and Lattice-Preferred Orientation in Wadsleyite: Experimental Constraints on the Rheology and Dynamics of Mantle Transition Zone

瓦兹利石中的塑性变形和晶格择优取向：地幔过渡带流变学和动力学的实验约束

• 批准号: 0510682
• 负责人: Shun-ichiro Karato
• 金额: --
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0510682&HistoricalAwards=false
• 关键词: Plastic; Deformation; Lattice; Preferred; Orientation

The transition zone of the Earth's mantle plays a key role in mantle dynamics. Recent high-resolution seismic tomography shows rich variety of interaction of convection current with the mantle transition zone. One of the key data that are needed to understand the nature of this interaction is the rheological properties of materials in this layer. However, experimental studies of plastic deformation are difficult and there has been no quantitative rheological data on materials in this region. In this project, the investigators will conduct the first well-controlled quantitative rheological measurements on wadsleyite, the most abundant mineral in the shallow transition zone. A newly developed apparatus, RDA (rotational Drickamer apparatus), will be used in this study. Deformation experiments will be conducted to large strains to obtain not only the rheological data but also the relationship between deformation geometry and seismic anisotropy. The results from this research will help understand the mechanical coupling between the upper mantle and the transition zone (that affects the geoid anomalies associated with mantle convection) as well as the deformability of slabs in the transition zone and the distribution and the mechanisms of deep earthquakes. The results on the relation between the lattice-preferred orientation of wadsleyite and flow geometry will be the first data set to interpret seismic anisotropy in terms of flow geometry in this region.

地幔过渡带在地幔动力学中起着重要作用。最近的高分辨率地震层析成像显示了对流与地幔过渡带的丰富多样的相互作用。了解这种相互作用的本质所需的关键数据之一是该层中材料的流变特性。然而，塑性变形的实验研究是困难的，一直没有定量的流变数据在这一地区的材料。在这个项目中，研究人员将对浅过渡区最丰富的矿物-硅镁石进行第一次控制良好的定量流变测量。一种新开发的装置，RDA（旋转Drickamer装置），将在这项研究中使用。将进行大应变变形实验，不仅获得流变数据，而且获得变形几何与地震各向异性之间的关系。 研究结果将有助于理解上地幔与过渡带之间的力学耦合（影响与地幔对流有关的大地水准面异常）、过渡带板块的变形能力以及深源地震的分布和机制。关于硅质岩的晶格择优取向与流动几何学之间关系的研究结果将成为解释该地区流动几何学地震各向异性的第一个数据集。