MARGINS Postdoctoral Fellowship: Deciphering the Role of Melt Segregation and Strain Partitioning in Rifting Continents

PI验证了应变速率的梯度导致熔体偏析程度的梯度，从而导致地震各向异性的梯度的假设。为此，他将使用三种方法：1)弹性特性建模；2)将模型应用于加利福尼亚湾的数据；3)通过实验来理解熔体偏析、应变分配和有效粘度之间的关系。熔体对各向同性速度的影响已经得到了很好的研究，但各向异性的影响还不太清楚。排列的橄榄石晶体、晶粒尺度上定向的熔体袋和米尺度的富熔体层将影响地震性质。与J-M合作，将这些影响纳入弹性性能的累积模型中，该模型以熔体偏析程度的形式编写。Kendall （university of Bristol）和Y. Takei （university of Tokyo）J. Gaherty （LDEO）在加利福尼亚湾进行的地震实验数据将与加利福尼亚湾的数据进行比较，以表征熔体分离的方向和程度。熔体偏析、应变分配和有效粘度之间的关系将受到部分熔融地幔岩石扭转几何变形实验的约束，从而获得高质量的流变学数据。研究的这一部分将与D. Kohlstedt和一名研究生（明尼苏达大学）合作完成。这个项目潜在的更广泛的影响将主要是支持一位年轻科学家的职业生涯。还将培训一名研究生（与Kohlstedt一起），并加强国际合作（日本，武井）。

The PI test the hypothesis that gradients in strain rate lead to gradients in degrees of melt segregation and thus gradients in seismic anisotropy. To do so he will use three approaches: 1) modeling of elastic properties, 2) application of model to data from Gulf of California, and 3) experiments to understand relationship between melt segregation, strain partitioning and effective viscosity.1. The effects of melt on isotropic velocities are fairly well studied, but anisotropic effects are less well understood. Seismic properties will be affected by aligned olivine crystals, oriented melt pockets at the grain scale, and meter-scale melt-rich layers. These effects are incorporated into a cumulative model of elastic properties, written in terms of the degree of melt segregation, in collaboration with J-M. Kendall (Univ. of Bristol) and Y. Takei (Univ. of Tokyo).2. Data from the seismic experiment in the Gulf of California conducted by J. Gaherty (LDEO) will be compared to data from the Gulf of California, to characterize the orientation and degree of melt segregation.3. The relationship between melt segregation, strain partitioning and effective viscosity will be constrained by deformation experiments on partially molten mantle rocks in torsional geometry, which allows for high-quality rheological data. This portion of the study will be performed in collaboration with D. Kohlstedt and a graduate student (Univ. of Minnesota). The potential broader impact of this project will be, primarily, to support the career of a young scientist. There will also be some training of a graduate student (with Kohlstedt) and increased international collaboration (Japan, Takei).