Slope Deformation Associated With Recent Tectonism and the Lasting Effect of Local Subsurface Geometry in the Taurus-Littrow Valley, Apollo 17 Landing Site

The South Massif and Taurus-Littrow valley represent a unique area for understanding recent geological processes on the Moon. The presence of two recent overlapping landslide deposits, and boulder falls, suggests that repetitive instability has affected the north-east facing slope of the South Massif. The presence of the young Lee-Lincoln lobate scarp associated with a thrust fault suggests that seismic shaking may have been an important factor in triggering surface changes and mass-wasting events in the area. In this work, we use the younger landslide deposit as a geomorphological marker. The age of the deposit, 70-110 Ma, is known due to the returned samples of the Apollo 17 mission, therefore allowing to set a time constraint to surface changes that have occurred since its emplacement. Here, we extend the body of evidence of slope deformation of the north-east slope of the South Massif post-dating the emplacement of the younger landslide deposit. We map boulder tracks, zones of disturbed regolith, summit and slope structures. We described their mutual relationships and their relationships with the topography and local tectonic structures. We identified features directly related to the local stress field, as well as features derived from gravitational adjustment following basal slope support removal due to reactivation of the ancient valley-bounding fault in reverse mode associated with the Lee-Lincoln thrust fault. Our interpretation favors a scenario in which recent tectonism, coupled with long-lasting influence of the subsurface geometry, has caused continuous slope deformation of the South Massif.

Automated summary

The South Massif and Taurus-Littrow valley provide valuable insights into recent geological processes on the Moon. The presence of overlapping landslide deposits and boulder falls suggests ongoing instability on the northeast slope of the South Massif. The discovery of a young lobate scarp and thrust fault implies seismic activity as a trigger for surface changes and mass-wasting events in the region. This study enhances our understanding of slope deformation on the South Massif beyond the younger landslide deposit.