Geology of Grimaldi Basin on the Moon: Evidence for volcanism and tectonism during the Copernican period

Abstract

The Grimaldi Basin, centered at (5.2° S, 68.6° W), is a ~400 km diameter highly degraded, Pre-Nectarian double-ring impact structure on the Moon located near the western edge of the Oceanus Procellarum. Hyperspectral data from Moon Mineralogy Mapper (M3), FeO estimates from Kaguya Lunar Multiband Imager (MI) data and TiO2 estimates from WAC 321/415 nm ratio have been used to study the compositional make-up of the Grimaldi mare basalt. Additionally, morphological studies and crater chronology have been carried out using moderate to very high-resolution images from Lunar Reconnaissance Orbiter (LRO) to decipher the geological evolution of the Grimaldi Basin. Mare Grimaldi are dominantly composed of clino-pyroxenes with olivine and/or of feldspathic mixing with lateral as well as depth-wise variations in composition. In the south central part, the basin experienced Copernican aged volcanism ~700 Ma ago resulting in the formation of olivine bearing basalts with high FeO and TiO2 content. Cross-cutting of small Copernican craters by fresh wrinkle ridges and lobate scarps has been observed at several places in the basin suggesting that tectonic activities occurred in the basin within the past ~50 Ma-1 Ga. Thus, similar to the Oceanus Procellarum region, Grimaldi Basin was also geologically active during the Copernican period.