The mechanical and thermal structure of Mercury’s early lithosphere

[1] Insight into the mechanical and thermal structure of Mercury’s early lithosphere has been obtained from forward modeling of the largest lobate scarp known on the planet. Our modeling indicates the structure overlies a thrust fault that extends deep into Mercury’s lithosphere. The best-fitting fault parameters are a depth of faulting of 35 to 40 km, a fault dip of 30 to 35, and a displacement of 2 km. The Discovery Rupes thrust fault probably cut the entire elastic and seismogenic lithosphere when it formed (4.0 Gyr ago). On Earth, the maximum depth of faulting is thermally controlled. Assuming the limiting isotherm for Mercury’s crust is 300 to 600C and it occurred at a depth of40 km, the corresponding heat flux at the time of faulting was10 to 43 mWm2. This is less than old terrestrial oceanic lithosphere but greater than the present hea