Detection of Mg-spinel bearing central peaks using M3 images: Implications for the petrogenesis of Mg-spinel

Abstract

Mg-spinel bearing lithologies, lacking abundant mafic materials, have been discovered with images acquired by the Moon Mineralogy Mapper (M3) aboard Chandrayaan-1. We conducted a systematic screening of lunar crater central peaks for the presence of Mg-spinel to address its distribution and petrogenesis. 38 Mg-spinel bearing crater central peaks were identified in this study out of 166 craters investigated. The results suggest that Mg-spinel is common in the lunar crust and appears to be extensive in the middle part of the lunar crust underneath Procellarum KREEP Terrane (PKT). Mg-spinel neither exclusively originated from deep layers (>10 km) nor necessarily coexist with the appearance of olivine or pyroxene. 15 Mg-spinel bearing central peaks originated from depth less than 10 km. Nine investigated central peaks only contain Mg-spinel and plagioclase without any detectable mafic materials. All those observations imply that the origin of Mg-spinel is possibly related to Mg-suite plutonism and assimilation between high Mg′ magma with anorthositic crust. The extensive distribution and Mg-suite related petrogenesis indicates that Mg-spinel bearing lithologies might represent a new member of Mg-suite rocks.