High heat flux on ancient Mars: Evidence from rift flank uplift at Coracis Fossae

Abstract

We have identified flexural uplift at the flanks of the Coracis Fossae Rift valley. Modeling the topography the elastic thickness is constrained to 10.3-12.5 km, the corresponding mechanical thickness and thermal gradient are 15-19 km and 27-33 K km^-1, respectively. The time of rifting is dated by evaluating the crater size-frequency distribution of key surface units related to the rifting. Thus, the heat flux between 3.5 and 3.9 Ga is calculated to be 54-66 mW m^-2. Furthermore, the stresses supported by the rift bounding faults are estimated to be below 5 MPa. We speculate that this weakness may be connected to the presence of water below the surface.