title: Lunar radar sounder observations of subsurface layers under the nearside maria of the Moon.
abstract: Observations of the subsurface geology of the Moon help advance our understanding of lunar origin and evolution. Radar sounding from the Kaguya spacecraft has revealed subsurface layers at an apparent depth of several hundred meters in nearside maria. Comparison with the surface geology in the Serenitatis basin implies that the prominent echoes are probably from buried regolith layers accumulated during the depositional hiatus of mare basalts. The stratification indicates a tectonic quiescence between 3.55 and 2.84 billion years ago; mare ridges were formed subsequently. The basalts that accumulated during this quiet period have a total thickness of only a few hundred meters. These observations suggest that mascon loading did not produce the tectonics in Serenitatis after 3.55 billion years ago. Global cooling probably dominated the tectonics after 2.84 billion years ago.
authors.affiliation: Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ono
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kumamoto
authors.forename: Hiromu
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Shoko
authors.initials: S
authors.lastname: Oshigami
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamaji
authors.forename: Takao
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Kasahara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Oya