Linking elastic and electrical properties to investigate partial melting in the deep mantle

Alisha Clark博士获得美国国家科学基金会EAR博士后奖学金，在美国西北大学和加州大学圣地亚哥分校斯克里普斯海洋学研究所开展研究和教育计划。该项目将侧重于进行实验室实验，以确定玄武岩成分硅酸盐熔体在高压和高温条件下的速度和电性能。硅酸盐熔体是传递热量和质量的最有效手段，在行星分化中起着关键作用。为了解释地球内部的物理状态，需要在与观测到的地球物理异常相对应的压力和温度下的实验数据。这个跨学科的研究项目涵盖了矿物物理、岩石学、固体地球物理、材料科学和凝聚态物理。克拉克博士将参与西北大学的Excite项目，该项目旨在增加埃文斯顿乡镇高中荣誉科学和数学课程中少数族裔学生的入学率。此外，她还将指导本科生进行与该项目相关的研究。这项研究将提供玄武岩熔体在高压和高温下的弹性和电学性质的信息，从而得出在地球过渡带（410-660公里）以下压力下硅酸盐熔体的状态方程。为了实现这些目标，克拉克博士将使用西北大学最新一代的千兆赫超声干涉仪来限制高压和高温下的声速和弹性模量。此外，首席研究员将使用Scripps的新型多砧系统对相同的硅酸盐熔体在高压和高温下进行电导率测量，并将这些趋势与速度联系起来，并确定熔体分数对电导率的影响。调查的最后一个组成部分将包括确定挥发物对玄武岩熔体速度和电导率的影响。这项调查的结果在解释地球物理观测时将是重要的，并将提供深度大于410公里的硅酸盐熔体物理性质的限制。

Dr. Alisha Clark has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education plans at Northwestern University and Scripps Institute of Oceanography at University of California, San Diego. The project will focus on conducting laboratory experiments to determine velocity and electrical properties of silicate melts of basaltic composition at high pressure and temperature conditions. Silicate melts are the most efficient means of transporting heat and mass and have played a critical role in planetary differentiation. Experimental data at pressure and temperatures corresponding to the observed geophysical anomalies are required to interpret the physical state of the Earth's interior. This interdisciplinary research project spans topics in mineral physics, petrology, solid-Earth geophysics, materials science, and condensed matter physics. Dr. Clark will be engaged in Project Excite at Northwestern University that aims increasing enrollment of underrepresented minority students in Evanston Township High School's honors science and mathematics courses. In addition, she will mentor undergraduate students in research related to this project.This investigation will provide information on both elastic and electrical properties of basaltic melts at high pressures and temperatures to produce an equation of state for silicate melts at pressures up to theEarth's transition zone, 410-660 km. To accomplish these goals, Dr. Clark will use the latest generation Gigahertz-ultrasonic interferometer at Northwestern University to constrain the acoustic velocities and elastic moduli at high pressure and temperatures. In addition, the principal investigator will use the new multi-anvil system at Scripps to perform electrical conductivity measurements on the same silicate melts at high pressures and temperatures and correlate these trends with velocity, as well as to determine the effect of melt fraction of electrical conductivity. The last component of the investigation will consist of determining the influence of volatiles on basaltic melt velocity and conductivity. The results from this investigation will be important when interpreting geophysical observations and will provide constrains on the physical properties of silicate melts at depths greater tan 410 km.