Rare, non-basaltic volcanism has been identified on the farside of the Moon, reports a paper published online this week in Nature Geoscience. These findings indicate that non-basaltic volcanism, which has previously been discovered on the lunar nearside, occurred in several locations across the entire Moon.
Bradley Jolliff and colleagues use images from the Lunar Reconnaissance Orbiter cameras and compositional spectral data from the Diviner lunar radiometer to assess the composition of the unusual Compton-Belkovich region on the lunar farside. The surface is made up of numerous domes with steeply sloping sides, which the team interpret as volcanic domes formed from viscous lava flows. The rocks are rich in thorium, silica and alkali-feldspar minerals, indicating that the lavas are compositionally evolved, and hence very different from the black basalts that make up the abundant lunar maria observed elsewhere on the Moon.
In an accompanying News & Views, Noah Petro writes: “It has been more than 40 years since the Apollo samples provided the first hint that compositionally evolved magmas might be distributed across the lunar surface. Yet, thanks to a suite of data from numerous recent missions, the Moon continues to surprise us.”