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. Plain Language Summary: The Apollo 17 mission collected samples from a landslide deposit, thanks to which the absolute age of 70–110 Ma was attributed. Knowing the age of the deposit allows to define a maximum age for events that happened after the landslide. By applying the geological principle of superposition, we identified structures that are superposed to the slope of the South Massif along which the landslide moved and to the deposit generated; therefore, these structures represent recent surface changes younger than 70–110 Ma. The relationships between the structures show that they have been generated by consecutive events, although we are not able to tell how much time has spanned in between. We analyzed the orientation of the slope structures and identified a group that can be directly related to the effects of the local tectonic stresses, and another group that has been generated by gravitational adjustment that has followed the removal of basal support due to reactivation of ancient faults. We conclude that the combination of recent tectonic stresses and old subsurface faults has been an important factor in setting favorable conditions for continuous slope deformation of the South Massif. Key Points: The slopes of the South Massif are characterized by different types of structures that are evidence of recent slope deformation processesRelationships between deformation and tectonic structures suggest that the South Massif has been affected by continuous instabilitySome deformation structures result from reactivation of the ancient valley‐bounding fault, associated with the Lee‐Lincoln scarp activity [ABSTRACT FROM AUTHOR]

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