Deep-Seated Mantle Plumes Detected Beneath the Moon’s Earth-Facing Hemisphere

The Moon’s mare basalts, which record over two billion years of lunar volcanic activity, hold key clues to the driving forces behind lunar magmatism. These igneous rocks are predominantly concentrated on the lunar nearside, giving rise to two competing hypotheses: one attributing the volcanism to shallow melting near the crust-mantle boundary, and the other to deep mantle upwellings following an early mantle overturn. However, in the absence of direct observational constraints on the deep structures of the Moon, the origin of this sustained, nearside-focused volcanism remains unresolved. Here, we present seismological evidence of deep thermal plumes beneath the lunar nearside today, revealing striking spatial correlations with surface enrichments in heat-producing elements. We propose that these plumes, likely originating from the core-mantle boundary, are remnants of post-overturn mantle dynamics that fuel mare volcanism. Our findings resolve the long-standing debate over the Moon’s internal heat sources by revealing that persistent deep thermal plumes beneath the nearside bridge ancient mare volcanism and present-day mantle dynamics. For the first time, this result establishes a unified framework that connects spatial and temporal clues across the Moon’s evolutionary history.