Experimental Studies of Physical Properties in the Fe-Si-S System at Planetary Core P, T Conditions

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Many important surface features of planets such as the magnetic field and plate tectonics are closely related to the physical and chemical processes happening inside the deep interior of a planet. Unfortunately, for most planets and planetary bodies, their deep interiors are forbidden regions for direct access and alternative approaches are needed. In this proposed research, simultaneous high pressure (up to 25 GPa) and high temperature (up to 2500 K) experiments will be conducted in our large volume presses to mimic the extreme conditions of the interior of terrestrial planets and some differentiated satellites in our solar system. The themes of Dr. Yong's research proposal will focus on the metallic cores of these planetary bodies, which consist primarily of iron, with a small amount of lighter elements such as silicon, sulfur as alloy constituents. The melting behavior and liquid density of iron-rich alloys have significant implications to many geophysical and planetary phenomena, including core composition, thermal structure, heat flow, magnetic field generation, and inner core solidification scenarios. A systematic experimental study of the high pressure melting boundary and liquid density of the Fe-Si and Fe-S systems will be carried out using our state of the art large volume presses, which include the largest capacity (3000 ton) multi-anvil press in North America, and analytical instruments at Western University. The proposed studies will answer questions that are key to understanding the deep interior of planets by providing the geophysical and planetary science community the critically needed data on two essential physical properties on liquid iron alloys at pressures up to 25 GPa. For certain chemical compositions and pressures, such data will be the first of its kind. These data will reveal additional insight into important questions related to the chemical and physical state, dynamics and processes occurring in the interiors of Earth and other terrestrial-type planetary bodies such as Moon, Mercury, Mars, Ganymede and Io (e.g. What light elements are present, and at what concentration, in the core? Is there a solid inner core and, if so at what depth and when did it start to crystallize? Are density differences between pure Fe and Fe alloy liquids large enough to power chemical convection in a liquid outer core?). Four HQP will receive extensive training in high pressure and high temperature experimental mineral physics that will provide transferable skills to prepare them for employment in academia, government and industry.