Physics Colloquium: Quingyang Hu
Quingyang Hu from the Advanced Photon Source at Argonne National Laboratory will be the featured speaker at an upcoming Department of Physics and Astronomy colloquium. His talk is titled, "Oxygen rich phases in Earth’s deep mantle."
Our conventional view of minerology in the deep Earth’s interiors has witnessed a sea change in the last decade. Here, we combine synchrotron X-ray techniques and first- principles calculation to predict, synthesize and characterize a pyrite-type phase FeO 2 Hx (0≤x≤1) that was found to stabilize at deep lower mantle conditions. Pyrite- FeO 2 has more oxygen content than hematite, which is known as the highest oxygen concentration iron oxide on Earth’s surface. The pyrite-phase is formed by oxidizing mantle minerals like iron oxides, iron or even ferropericlase by reacting with water possibly from deep hydrous minerals. The high-density pyrite-phase accumulates at the core-mantle boundaries and provides new mechanisms to explain enigmatic seismological structures of that region. For pyrite-FeO 2 Hx, we further characterize it features ferrous iron in respect to partial covalent bonded oxygen at a paired O 2 2- state. Our study suggests that mineralogy in deep mantle may feature a variety of chemical reactions that creates oxygen-rich domains. Such phase transformation and chemistry has imposed an important role in the geophysical properties and element cycling of Earth’s interiors.
This event is free and open to the public.
Department of Physics and Astronomy