Collaborative Research: Effects of ferric iron on heat transport in Earth's mantle

Heat transport in Earth’s mantle affects plate tectonics, volcanism, and the magnetic field. How materials carry heat varies with depth, temperature, and composition. This project tests how oxidized iron changes heat transport in the mantle. Oxidized iron-rich rock in tectonic plates subducts to the mantle and may be enriched at the base of the mantle. In this project, researchers will conduct experiments to grow mantle-relevant crystals with compositions including oxidized iron. They will measure heat flow in these crystals at high pressures and temperatures. The results will allow them to examine how reactions between Earth's atmosphere and mantle rock affect the Earth’s dynamics as a consequence of their ability to transport heat. This project will enable a new technique at Michigan State and establish collaboration between researchers in Michigan and Taiwan through experiments and shared graduate student and postdoctoral scholar training. Michigan undergraduate students will be introduced to geology of Taiwan and thermal properties of Earth materials. Thermal conductivity of mantle silicates modulates the Earth’s dynamics. Recent studies have investigated the effects of iron and pressure-induced spin transitions on thermal conductivity in mantle minerals. However, these studies have been limited to reduced compositions such as ferropericlase and ferrous-iron-rich bridgmanite. The researchers will use ultrafast time-domain thermo-reflectance (TDTR) spectroscopy in diamond anvil cells to determine the lattice thermal conductivity of oxidized ferric-iron-rich bridgmanite and post-perovskite. They will isolate the effects of the pressure-driven spin pairing transition in ferric-iron-bearing bridgmanite and effects of aluminum versus ferric iron on heat transport. This collaboration between Michigan State University, the University of Michigan, and the Academia Sinica in Taiwan will combine complementary expertise in crystal growth, extreme high pressure and temperature experiments, and heat flow measurement to measure how differences in oxidation in the mantle impact mantle convection. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.