Prof. Susannah Dorfman [Michigan State University, USA]

Title: Iron-rich silicates in Earth’s Lower Mantle | 地球下地幔的富铁硅酸盐矿物

Time: 10:00 - 11:00 AM, Wednesday, November 2, 2016

Place: Conference room 410, HPSTAR (Shanghai)

Host: Dr. Li Zhang

Abstract

The behavior of iron in silicates at high pressure is key to understanding Earth’s mantle dynamics and chemistry. In the lower mantle’s dominant phase, perovskite-structured (Mg,Fe,Al)(Fe,Al,Si)O3, recently named bridgmanite, and its higher pressure polymorph post-perovskite, iron can occupy both the larger Mg-site and the smaller Si-site and exhibit multiple valence and electronic spin states. This complexity has hampered efforts to characterize the effects of iron-incorporation on physical properties such as density and seismic velocity and chemical behavior such as partitioning between bridgmanite and (Mg,Fe)O ferropericlase. To characterize iron in lower mantle silicates, I have performed comprehensive X-ray diffraction, spectroscopy and microscopy experiments on samples compressed in the laser-heated diamond anvil cell to pressures up to 180 GPa. I will discuss the implications of these experiments for the composition of iron-rich mantle heterogeneities.

Biography of the Speaker:

Susannah Dorfman simulates the conditions inside Earth and other planets using experiments in the laser-heated diamond anvil cell at high pressures (up to 2.5 Mbar) and temperatures (up to 6000 K). She is interested in the effects of these extreme conditions on phase equilibria and physical properties of planetary materials including mantle silicates and carbonates. Her laboratory probes crystal structures and compositions in situ using synchrotron diffraction and spectroscopy and ex situ using electron microscopy techniques.

Susannah is an assistant professor at the Department of Earth and Environmental Sciences of MSU. She comes to MSU after working as a postdoctoral scientist in the Institute of Condensed Matter Physics at the Ecole Polytechnique Federale de Lausanne (Swiss Federal Institute of Technology, Lausanne) in Switzerland. She received degrees from Princeton University (Ph.D. 2012, M.S. 2008) and the Massachusetts Institute of Technology (S.B. 2005).