Mare Domes in Mare Tranquillitatis: Identification, Characterization, and Implications for Their Origin

Mare domes, small shield volcanoes typically <∼30 km diameter, are part of the spectrum lunar volcanic features that characterize extrusive basalt deposits. We used new spacecraft data to document these in Tranquillitatis, among oldest maria and site commonly interpreted as an ancient degraded non-mascon impact basin. found 283 known suspected mare with majority (n = 229) concentrated on a broad, ∼450 circular topographic rise eastern Tranquillitatis. The domes (median diameter 5.6 km, height 68 m, volume 0.7 km3) contain summit pits (74%; median 0.8 km), exhibit minor compositional variability between surrounding flows, suggesting both supply embayed by flows. Based their characteristics associations, we interpret have been built from individual low-volume (<∼10–100 km3), low volatile content, short duration, cooling-limited eruptions. broad is ∼920 m high (volume ∼1.6 × 105 be multiple occurrences eruptions, plains volcanism style. This implies shallow mantle source region capable supplying distributed dike-emplacement eruption events over area 1.75 km2 early history (∼3.7 Ga). difference Tranquillitatis younger mare-filled mascon basins attributed more thermal state crustal structure viscously relaxed basin, shallower magma present earlier history.