Experimental quantification of the degassing of chalcophile and siderophile elements from metal and sulfide melts

The chemical composition of magmatic iron meteorites provides fundamental insights into planetary accretion processes. They are distinguished based on their trace element compositions and could represent the cores of more than 50 parent bodies1. The primary difference between the different groups is the degree of volatile element depletions, which increases from class I to IV iron meteorites2. The volatile element loss could have occurred prior to (i.e. nebular) or during parent body accretion/differentiation, for example during exposure of a liquid core following a catastrophic impact3. Investigating the mechanisms of volatile loss from requires experimental constraints on their volatility, for example during evaporation. We therefore experimentally quantified the evaporation of the nominally volatile, transitional and refractory chalcophile and siderophile from Fe-C and Fe-S melts, respectively. Their evaporation was studied as a function of pressure (high vacuum to 1 bar), temperature (1573-1823 K), composition (Fe, FeS) and time (min´s to hours). The results show that the volatilities are significantly different than previously assumed, and that their volatility may be strongly and distinctly affected by the composition of the melt from which they evaporate. The new data is discussed in light of current models that describe volatile element depletions in magmatic iron meteorite parent bodies.

(1) Goldstein et al. (2009) Chemie Der Erde - Geochemistry (2) Scott & Wasson (1975) Rev Geophys (3) Kleine et al. (2018) LPSC 2083.