Fe-Oxide Microspherule Fragment from Chang’E-5 Soil Sample: Possible Evidence for Lunar Fumarole Activity

Abstract

Earlier discovery of magnetite in the Chang’E-5 regolith raised the question about a source of oxidized material in young basaltic volcanism area of the landing site. Here we report the find of Fe-oxide microspherule fragment found in the Chang’E-5 sample, which retained its original structure suggesting it could be magnetite polyframboid or dendrite-like microspherule. The size and texture of the object suggest its prolonged formation from a Fe-rich oxidized environment. Shape and the growth morphology observed on the microcrystals surface suggest a possible free growth from gaseous or fluid phase. Volcanic gas/fluid accumulated within erupted lava flow could be an oxidizing agent at the late stage of eruption or during post-eruption fumarolic activity. If fumaroles existed in the volcanic complexes of Oceanus Procellarum, then the products should be reworked during regolith gardening afterwards, having preserved traces of such processes in the regolith.