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Penelope King Colloquium Abstract (Feb 3, 2016)

Gas-Solid Reactions in Earth and Planetary Systems

A fundamental question in earth and planetary systems is: how are chemical elements distributed from high temperature in the planet's interior to low temperatures at the surface, atmosphere and/or ocean? This question is at the heart of understanding how life originated, how planetary atmospheres develop, how ore deposits form and how climate is regulated. Currently, there is no consensus on the sources and sinks of elements on Earth now, nor over Earth's history, in part because some elements are volatile: preferring to be in the gas phase and they leave little trace.

Gas mixtures play a crucial role in distributing elements between different parts of Earth and planet-forming systems over a range of settings and temperatures. Despite the fundamental role of gases in geochemical cycles, few experiments exist on gas-solid or gas-melt reactions and the molecular-scale reaction mechanisms are poorly constrained by experiment, theory or field observations. Our recent work shows that anhydrite growth on plagioclase in the presence of SO2 gas is extraordinarily rapid at high temperatures. I will introduce our investigations of gas-solid reactions in the Earth and planetary processes using experiments, state-of-the-art analysis of laboratory and natural materials, and thermodynamic modelling of the processes.