A large long-lived central-vent volcano in the Gardner region: Implications for the volcanic history of the nearside of the Moon

Abstract Large shield-building volcanic structures (>30 km) with central vents are rare on the Moon. The most popular candidate targets of lunar large shield volcanoes are volcanic complexes on the lunar nearside within the compositionally evolved Procellarum KREEP terrane (PKT). However, there is a unique mass concentrated volcanic complex not within the PKT, namely Gardner (16.1°N, 34.1°E, ∼70 km in diameter) on the northern edge of Mare Tranquillitatis, whose origin is enigmatic. Here we use multi-source remote-sensing data to assess its morphology, composition and stratigraphy to better understand its formation and evolution. Results show that domes, sinuous rilles, and an irregular depression exist in this region. Gardner has experienced four stages of volcanic activities with absolute model ages from 3.90 to 2.96 Ga, contemporaneous with the main volcanic activity periods of the lunar nearside. An area with relatively low albedo, high FeO and TiO2 contents, low rock abundances, and young surface age is identified in the southeast part of the irregular depression at the summit of the plateau, which could have been the result of a long-lived eruptive center. Quasi-circular positive Bouguer-gravity anomaly suggests either sill/laccolith intrusions or large conduit solidifications underneath this area, which could be related to its surrounding radially distributed lava domes, wrinkle ridges and faults. We conclude that Gardner is the largest central-vent volcano identified so far on the Moon, and it provides an essentially new perspective and supplement for the knowledge of the lunar nearside volcanism.