Dynamics of Partially Molten Regions: Development of New Tools for Understanding Melt Localization by Mechanical Deformation

明镜周刊EAR-0207851地幔部分熔融区域内熔体和固体的分布是控制这些区域的动力学、性质和组成的关键参数之一。野外观测、实验和理论都表明，熔体应该在深处以某种形式的沟道化网络分布，但产生这些网络的物理机制仍然没有被很好地理解。这个项目将开发新的工具来研究流动局部化的力学不稳定性，基于流体在具有强烈变化的固体剪切粘度的可变形渗透介质中的流动。这些工具将补充由于反应性熔体传输而导致的流动定位的现有模型。在非均匀介质中开发精确的流动解算器在数值上是非常具有挑战性的，然而，这项研究将以David Kohlstedt实验室(美国明尼苏达州大学)最近关于流动诱导熔体局部化的实验为指导，这些实验为该理论提供了明确的诊断测试。直接将理论和实验结合起来的机会很少，研究人员计划与科尔斯泰特小组密切合作。然而，该项目的最初目标是开发所需的数字工具。一旦开发并验证了实验结果，它们将被用于将实验结果外推到更大的范围，并研究与地质相关的系统，如大洋中脊和岛弧下的熔体运输。

SpiegelmanEAR-0207851The distribution of melt and solid within partially molten regions of the Earth's mantle is one of the key parameters controlling the dynamics, properties and compositions of these regions. Field observations, experiments and theory all suggest that melt should be distributed in some form of channelized network at depth but the physical mechanisms for producing these networks are still not well understood. This project will develop new tools to investigate mechanical instabilities for flow localization based on fluid flow in deformable permeable media with strongly variable solid shear viscosity. These tools will complement existing models for flow localization due to reactive melt transport. Developing accurate flow solvers in heterogeneous media is numerically quite challenging, however, the investigation will be guided by recent experiments from David Kohlstedt's laboratory (U. Minnesota) on flow induced melt localization that provide clear and diagnostic tests for the theory. The opportunity to directly combine theory and experiment is rare and the investigators plan to work closely in consultation with the Kohlstedt group. However, the initial objective of this project is the development of the needed numerical tools. Once developed and validated with the experimental results, they will be used to extrapolate the experimental results to larger scales and investigate geologically relevant systems such as melt transport beneath mid-ocean ridges and island arcs.--