Premium
Mare Domes in Mare Tranquillitatis: Identification, Characterization, and Implications for Their Origin
Author(s) -
Qiao Le,
Head James W.,
Wilson Lionel,
Chen Jian,
Ling Zongcheng
Publication year - 2021
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1029/2021je006888
Subject(s) - geology , volcano , volcanism , shield , basalt , structural basin , extrusive , dike , mantle (geology) , lunar mare , geochemistry , seismology , petrology , geomorphology , tectonics
Mare domes, small shield volcanoes typically <∼30 km diameter, are part of the spectrum of lunar volcanic features that characterize extrusive basalt deposits. We used new spacecraft data to document these in Mare Tranquillitatis, among the oldest maria and the site commonly interpreted as an ancient degraded non‐mascon impact basin. We found 283 known and suspected mare domes, with the majority ( n = 229) concentrated on a broad, ∼450 km circular topographic rise in eastern Mare Tranquillitatis. The domes (median diameter 5.6 km, height 68 m, volume 0.7 km 3 ) contain summit pits (74%; median diameter 0.8 km), and exhibit minor compositional variability between domes and surrounding flows, suggesting that domes both supply and are embayed by these flows. Based on their characteristics and associations, we interpret the small shield volcanoes to have been built from individual low‐volume (<∼10–100 km 3 ), low volatile content, short duration, cooling‐limited eruptions. The ∼450 km broad volcanic rise is ∼920 m high (volume ∼1.6 × 10 5 km 3 ) and is interpreted to be built from multiple occurrences of small shield eruptions, a shield plains volcanism style. This implies a shallow mantle source region capable of supplying distributed dike‐emplacement and eruption events over an area of 1.75 × 10 5 km 2 early in mare volcanism history (∼3.7 Ga). The difference between Mare Tranquillitatis and younger mare‐filled mascon basins is attributed to the more ancient thermal state and crustal structure of the viscously relaxed Tranquillitatis basin, and a shallower broad magma source region present in earlier lunar thermal history.