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

Clark Alisha N, Davis CA

Investigators

Abstract

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 the Earth'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.