3D and 2D Clast Analysis of Apollo 17 Core Sample 73002: Insights Into the Light Mantle Dynamics and Regolith Reworking

The Light Mantle deposit in Taurus-Littrow Valley, Apollo 17 landing site, represents the only extraterrestrial landslide to have ever been studied in situ. The origin and hypermobility of the Light Mantle remain debated. A core sample of the Light Mantle was collected by Apollo 17 astronauts and kept sealed awaiting for advanced imaging and analytical techniques to be available in the future. The core, made up of two samples, was recently opened as part of the NASA Apollo Next Generation Sample Analysis initiative. The availability of the core for study represents an unprecedented opportunity to investigate the structures of the Light Mantle at previously unsampled depths. In this work, we used high-resolution X-ray computed tomography scans and high-resolution scans of thin sections of the upper 20 cm of the core, sample 73002. We conducted 3D clast-size analysis and investigation of clast morphological fabric. Our results (a) suggest the absence of large clasts (>1 cm) in the uppermost 5 cm, consistent with the reworked regolith layer identified in previous studies of other lunar samples and (b) show the presence of clast-cortex aggregates, which are considered evidence of granular flow dynamics during the Light Mantle emplacement. Our work represents the first study to conduct a 3D clast analysis of a lunar core sample. As such, it constitutes an important step in showing the novel information that can be extracted. Moreover, it presents a potential workflow for studying lunar core samples that will be collected during future missions to the Moon.