Rupes Recta and the geological history of the Mare Nubium region of the Moon: insights from forward mechanical modelling of the ‘Straight Wall’

Abstract

Abstract Rupes Recta, also known as the ‘Straight Wall’, is an individual normal fault located in eastern Mare Nubium on the nearside of the Moon. Age and cross-cutting relationships suggest that the maximum age of Rupes Recta is 3.2 Ga, which may make it the youngest large-scale normal fault on the Moon. Based on detailed structural mapping and throw distribution analysis, fault nucleation is interpreted to have occurred near the fault centre, and the fault has propagated bi-directionally, growing northwards and southwards by segment linkage. Forward mechanical modelling of fault topography gives a best-fitting fault dip of approximately 85°, and suggests that Rupes Recta accommodated approximately 400 m of maximum displacement and extends to a depth of around 42 km. The cumulative driving stresses required to form Rupes Recta are similar in magnitude to those that formed normal faults in Tempe Terra, Mars. The spatial and temporal association with Rima Birt, a sinuous rille to the west of Rupes Recta, suggests a genetic relationship between both structures and implies regional extension at the time of formation.