[M-IS21] Planetary Volcanology

[MIS21-P03] Lunar laccolith on the Oceanus Procellarum region

*Ken Ishiyama¹ (1.International Professional University of Technology in Tokyo)

Keywords:Laccolith, SELENE

Laccoliths are a raised landform formed by magma intrusion between strata [Turcotte, Geodynamics, 2020]. In our familiar celestial body, the Moon, many landforms that appear to be laccoliths have been reported [e.g., Wöhler et al., Icarus, 2009]. Here, we show that three well-known areas in Oceanus Procellarum on the Moon (Mons Rümker, the Aristarchus plateau, and the Marius Hill) are laccolithic landforms. The area around Mons Rümker is surrounded by relatively young lava, which is at least 190-360 m thick based on the lunar subsurface radar observation. Applying the laccolith model [Michaut, JGR, 2011] to the three areas, Mons Rümker is a laccolith with a radius of ~65 km and a height of ~1 km. Similarly, the Aristarchus Plateau is a radius of ~150 km and a height of ~1.1 km, and the Marius Hill is a radius of ~120 km and a height of ~1.5 km. The depth of magma intrusion is estimated to be 4-6 km at Mons Rümker, 15-36 km at Aristarchus Plateau, and 9-21 km at Marius Hill, assuming the width of the lunar dike. Based on the geologic map near Mons Rümker [Zhao et al., JGR, 2017], Mons Rümker was formed by magma intrusion beneath lava deposited ~3.5 billion years ago, and the magma intrusions at the Aristarchus Plateau and Marius Hill were caused inside the crust or at Moho surface. Therefore, the relatively large laccoliths in Oceanus Procellarum suggest the formation of easily penetrable strata.