Speaker 1 – Dr. Richard Thomas
Title: The Chemical Behaviour of Chlorine and Sulfur in Silicate Melts
Abstract: Understanding volatile behavior in silicate melts requires quantifying activity-based thermodynamics under controlled conditions. We developed experimental methodologies to isolate the roles of oxygen fugacity, volatile fugacity (Cl, S), melt composition, temperature, and pressure. High-temperature experiments (1400 °C, 1 bar–2.5 GPa) reveal how both sulfur and chlorine dissolve into silicate melts, and how their speciation and solubilities vary systematically across geological processes, both with distinct trends reflecting their different incorporation mechanisms. These results provide the first internally consistent constraints on the activities of S and Cl in silicate melts, offering new insights into volatile speciation, degassing, and redox evolution in magmatic systems.
Biography: Post doctoral researcher in experimental petrology – I am most interested in trying to design well constrained experiments, so then we can test just one variable at a time. Also a lover of Salt and vinegar, and sulfur.
Contact: richard.thomas@earth.ox.ac.uk
Speaker 2 – Kate Bormann
Title: The Fate of Venusian Chlorine
Abstract: Many aspects of Venus remain uncertain. The transport of volatiles such as chlorine is linked to world-forming processes such as magmatic degassing and planetary differentiation, and so can offer clues to the geologic evolution of a planet. On Earth, chlorine has efficiently degassed and today is strongly concentrated in the terrestrial surface environment, while on Venus the atmosphere contains mere trace levels of HCl. This talk presents experimental and modelling work that shows a substantial chlorine budget may have degassed into the early Venusian atmosphere, then later dissolved into silicate melts on Venus’s surface and sequestered in chlorine-bearing crustal minerals.
Biography: Kate Bormann is a PhD student in the experimental petrology group at the University Oxford, studying the role of halogens on Venus.
Contact: katherine.bormann@wolfson.ox.ac.uk
To join virtually: Zoom
Recording: Zoom Recording (will be available within a week after the seminar)