Morphological and chronological mapping of Petavius crater, nearside of the Moon

Abstract

Petavius, a complex crater from the late Imbrian epoch, features a giant central peak, numerous smaller peaks, and an inner terraced wall arising nearly 3 km above the crater floor. The region has seen periods of tectonic and volcanic activity. A meter-scale detailed mapping of LROC- Narrow Angle Camera (NAC) images was carried out to understand the tectonic features and associated volcanic history under this crater. We found many fragmented blocks, fields of striated boulders, grabens, layering near grabens and striated boulders, rock exposures, and many fractures from NAC mapping, indicating magma creating pressure underneath the floor of a crater. The fractures identified from NAC images are probably linked with an underlying magmatic sill of high-density bodies. Crater size-frequency distribution analysis indicates that magmatic activity likely persisted for ∼2.75 Ga in the Petavius crater. It is noteworthy that this relatively recent age of volcanism has not been reported previously. The crustal thickness of the study region varies from 27 to 40 km; at the mapped tectonic features and volcanic regions, the crustal thickness of 30–34 km is found. The unique tectonic environment of the Petavius crater, in combination with the associated morphological variation and numerous exposures of mafic, suggests that the crater formed in phases associated with its structural and morphologic features and is derived from the lower crust. The morphometric analysis and previous studies support a model of magmatic intrusion and sill formation within the fractured crust beneath the crater floor; such a sill would be a likely source both for effusive mare material erupted through floor fractures into low-lying portions of the crater floor. The tectonic system on the floor of the crater was the result of post-impact processes.