Mechanical modeling of thrust faults in the Thaumasia region, Mars, and implications for the Noachian heat flux

Insight into the state of the early martian lithosphere is gained by modeling the topography above surface breaking thrust faults in the southern Thaumasia region. Crater counts of key surface units associated with the faulting indicate a scarp emplacement in the late Noachian–early Hesperian periods between 4.0 and 3.7 Gyr. The seismogenic layer thickness at the time of faulting is constrained to 27–35 km and 21–28 km for the two scarps investigated, implying paleo geothermal gradients of 12–18 and 15–23 K km−1, corresponding to heat flows of 24–36 and 30–46 mW m−2. The heat flow values obtained in this study are considerably lower than those derived from rift flank uplift at the close-by Coracis Fossae for a similar time period, indicating that surface heat flow is a strong function of regional setting. If viewed as representative for magmatically active and inactive regions, the thermal gradients at rifts and scarps span the range of admissible global mean values. This implies d T / d z = 17 – 32   K km −1 , with the true value probably being closer to the lower bound.