Forward Mechanical Modeling of the Amenthes Rupes Thrust Fault on Mars

Abstract

Amenthes Rupes overlies one of the largest thrust faults on Mars, with structural topography accurately measured by MOLA. Forward mechanical models successfully predict the surface topography across this large contractional structure. The best-fitting fault parameters are: fault dip angle, 25-30°; depth of faulting, 25-30 km; and fault offset, 1.5 km. These first-order results are insensitive to either the offset distribution along the fault or crustal material properties. Both very shallow (e.g., ~15 km) and very deep (~45 km) depths of faulting can be ruled out, as can significantly different dips and offset magnitudes. Amenthes Rupes may span the ancient seismogenic lithosphere in the Martian Noachian highlands, implying maximum values at the time of faulting for heat flux of ~54-70 mW m-2 and paleogeothermal gradient of 15-20 K km-1.