Mid-infrared spectroscopy of sulfidation reaction products and
implications for Sulfur on Mercury
Abstract
We propose that the observed enrichment of sulfur at the surface of
Mercury (up to 4 wt.%) is the product of silicate sulfidation reactions
with a S-rich reduced volcanogenic gas phase. Here, we present new
experiments on the sulfidation behavior of olivine, diopside, and
anorthite. We investigate these reaction products, and those of
sulfidized glasses with Mercury compositions previously reported, by
mid-IR reflectance spectroscopy. We investigate both the reacted bulk
materials as powders, as well as cross-sections of the reaction products
by in-situ micro-IR spectroscopy. The mid-IR spectra confirm the
presence of predicted reaction products including quartz. The mid-IR
reflectance of sulfide reaction products, such as CaS (oldhamite) or MgS
(niningerite), is insufficient to be observed in the complex run
products. However, the ESA/JAXA BepiColombo mission to Mercury will be
able to test our hypothesis by investigating correlated abundances of
sulfides with other reaction products such as quartz.