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

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.

Automated summary

This study found that young lunar basalts have a lower abundance of olivine than previously suggested, based on the analysis of Chang'e-5 samples and Moon Mineralogy Mapper data. The research also reassessed the model ages of these basalts and discovered an increasing trend in TiO2 abundance with time. The presence of young basalts around 2.0 billion years ago indicates ongoing mare volcanism and the need for additional heat sources or mechanisms compared to older basalts. Therefore, further investigation and sampling of young mare samples from Chang'e-5 and other potential sites are necessary to understand the late lunar thermal and volcanic history.