Measurements of Thermal Conductivity of Deep Earth Minerals

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

The heat transport across the core/mantle boundary places the largest constraint on the whole-Earth heat budget, with ramifications for behavior extending well beyond the physical boundary itself-including generation and power of the dynamo-generated magnetic field, timing of inner-core formation, the driving force and style of whole-mantle convection including the surface manifestation of plate tectonics. This experimental study will take advantage of new precision in temperature measurements in the laser heated diamond cell laboratory at UCLA to measure the pressure and temperature dependence of thermal conductivity of important Earth materials (including iron and alloys, silicates and oxides) at temperatures and pressures mirroring the conditions of Earth's deep interior. In the first approach, temperature gradients will be measured for a series samples at high pressures, and best-fit thermal conductivity models will be chosen from diamond cell heat flow models. A second, more "frontiers" approach, will provide a measurement of temperature gradient in two dimensions, which will be used to measure anisotropic thermal diffusivity in natural and engineered laminar composites. Intellectual Merit: The results will be used to help address key scientific questions regarding heat transport in the Earth's deep interior, including (1) What is the heat flow through the core/mantle boundary? (2) Does the Earth's core require an internal source of heating? and (3) Can chemical heterogeneities in the Earth's lowermost mantle contribute to the style of convection through differences in heat flow mechanisms? Broader Impacts: This experimental system is the focal point of a laboratory-based state of the art research and research-training program in mineral physics at UCLA. The measurements performed by this study are a necessary first step required to calibrate and test the PI's laser heating system's ability to accurately and reproducibly measure temperature and associated gradients. The PI is an active member of the NSF-sponsored COnsortium for Mineral Physics Research at High Pressure (COMPRES) community, and innovations in temperature measurement at UCLA will be presented and exported to community facilities where feasible. In addition, the PI is actively involved in formal and informal science education spanning the pre-school through postdoctoral levels.