Global thrust faulting on the Moon and the influence of tidal stresses

Abstract

Lunar Reconnaissance Orbiter Camera images reveal a vast, globally distributed network of over 3200 lobate thrust fault scarps, making them the most common tectonic landform on the Moon. Based on their small scale and crisp appearance, crosscutting relations with small-diameter impact craters, and rates of infilling of associated small, shallow graben, these fault scarps are estimated to be younger than 50 Ma and may be actively forming today. The non-random distribution of the scarp orientations is inconsistent with isotropic stresses from late-stage global contraction as the sole source of stress. We propose that tidal stresses contribute significantly to the current stress state of the lunar crust. Orbital recession stresses superimposed on stresses from global contraction with the addition of diurnal tidal stresses result in non-isotropic compressional stress and thrust faults consistent with lobate scarp orientations. The addition of diurnal tidal stresses at apogee result in peak stresses that may help trigger coseismic slip events on currently active thrust faults on the Moon.