Mineralogy and chronology of the young mare volcanism in the Procellarum-KREEP-Terrane

Abstract

Young lunar mare basalts are recent volcanic products distributed mainly in the Procellarum-KREEP-Terrane. However, these young basalts were never investigated in situ until 2013 by Chang’e-3, and then sampled by Chang’e-5 in 2020. Using the returned Chang’e-5 samples as ground truth, and examining Moon Mineralogy Mapper data globally, we found the young basalts containing less abundant olivine (<10%) than previously suggested. The Chang’e-3 and Chang’e-5 basalts belong to a type of underrepresented basalt. We reassessed the model ages of the young basalts using the new chronology function calibrated by the Chang’e-5 samples and found the young basalts have a trend of increasing TiO2 abundance with time. The young basalts with an age of around 2.0 Ga (billion years ago) are widespread in the Procellarum-KREEP-Terrane, including the Chang’e-5 unit. This indicates mare volcanism was still active at that time and an additional heat source or mechanism may be needed compared to older basalts. Young mare samples from Chang’e-5 and other potential sites are needed to constrain the late lunar thermal and volcanic history.