¹Maximilian P. Reitze,^1,2Christian Renggli,¹Andreas Morlok,¹Iris Weber,³Uta Rodehorst,¹Jasper Berndt,¹Stephan Klemme,¹Harald Hiesinger
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2024JE008483]
¹Universität Münster, Institut für Planetologie, Münster, Germany
²Max Planck Institute for Solar System Research, Göttingen, Germany
³MEET – Münster Electrochemical Energy Technology, Münster, Germany
Published by arrangement with John Wiley & Sons

We synthesized the solid solution between the sulfides CaS (oldhamite) and MgS (niningerite). Electron microprobe and X-ray diffraction showed homogeneous and pure samples after the synthesis. The calculated lattice parameters fit to earlier literature data. Mid-infrared spectroscopy of the samples reveal that the produced sulfides were fragile and tend to alternate very fast. However, we were able to provide clean reflectance spectra of all samples. The spectra of un-altered samples show no peaks or bands but a rather constant spectrum within the analyzed spectral range between 7.0 and 12.5 μm. The altered spectra contain signatures of sulfates and carbonates and probably further compounds. The gathered data help to understand the formation conditions of the studies sulfides as it shows that the solvus exists in the CaS-MgS system between 1000°C and 1200°C. In addition, the infrared data will help to improve remote sensing in the mid-infrared of planetary objects that might be covered with sulfide containing material like asteroids or Mercury.

^1,2C. P. Haupt,^1,3C. J. Renggli,¹A. Rohrbach,¹J. Berndt,¹S. Klemme
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008239]
¹Institut für Mineralogie, Universität Münster, Münster, Germany
²CNRS, Université d’Orléans, Orléans, France
³Max-Planck-Institute for Solar System Research, Göttingen, Germany
Published by arrangement with Johhn Wiley & Sons

High-pressure and high-temperature experiments were conducted to simulate melting of a hybrid cumulate lunar mantle. The experimental results show that intermediate to high-Ti lunar pyroclastic glasses (>6 wt% TiO2) can be produced by partial melting of lunar cumulates. High-Ti basalts are generated when the ilmenite/clinopyroxene ratios in the lunar mantle cumulates are between 1/1 and 4/1, depending on the degree of melting. The presence of an urKREEP component in the mantle cumulate strongly influences Al2O3/CaO of the melts. The experiments provide strong evidence for the model that the compositional diversity of lunar basalts is a consequence of a gravitational overturn of the lunar interior after the lunar magma ocean had solidified. Ilmenite/clinopyroxene in the cumulate mantle, which generates high-Ti melts at partial melting, do not comprise the ratios in ilmenite-bearing cumulates (IBC), which crystallized after ∼90% solidification of the lunar magma ocean and indicate local accumulation of ilmenite in the overturned lunar mantle. However, to fully match the natural composition of the most primitive lunar samples, secondary processes such as assimilation are still required.