A New Framework for Mapping Lunar Mare Basalt Units Using Passive Microwave Data: A Case Study in Mare Imbrium

Mare basalts are products of partial mantle melting, and their spatiotemporal distribution provides key constraints on the thermal evolution of the Moon. Conventional mapping from optical data is hindered by space weathering, ejecta contamination, and inconsistent criteria. To address these issues, this study introduces a new framework that integrates multi-channel, multi-temporal brightness temperature (TB) features derived from a 24-hour complete TB dataset of the Chang’e-2 Microwave Radiometer (MRM) with the Random Forest algorithm. Applied to Mare Imbrium, the framework achieves high sample-level accuracy and, with hierarchical clustering, effectively reduces inter-unit patchiness. Compared with previous optical- and radar-based interpretations, the resulting geological map redefines basalt unit boundaries at the MRM pixel scale (0.125°), refines stratigraphic relationships, and reveals regolith thermophysical variations linked to impact modification and volcanic resurfacing. These results highlight the potential of passive microwave remote sensing to bridge surface and subsurface observations and provide a reproducible and traceable framework for planetary geological mapping.