Fe-Ni-P-S Melt Pockets in Elga IIE Iron Meteorite: Evidence for the Origin at High-Pressures Up to 20 GPa

Abstract

Here we report new data on high-pressure microstructures in Elga group IIE iron meteorites, made of solidified Fe-Ni-P-S melt pockets and microcrystalline aggregates, which could be formed only at high pressures and temperatures according to the experimental data. The bulk composition of the melt pockets and crystals correspond to the Fe3P-Fe3S solid solution with the closure of an immiscibility gap at pressures near 20 GPa in static experiments. Some other melt pockets fit with the Fe2S-Fe2P compositions, which could also correspond to high pressures and temperatures. The results suggest a late shock episode during the formation of the IIE iron parent body, which may be prior or due to the final disruption that caused the meteorite arrival to Earth. It also has an important implication to the shock features in other meteorites, such as ureilite.