Abstract
The apparent end of the internally generated Martian magnetic field at 3.6-4.1 Ga is a key event in Martian history and has been linked to insufficient core cooling. We investigate the thermal and magnetic evolution of the Martian core and mantle using parameterized models and considered three improvements on previous studies. First, our models account for thermal stratification in the core. Second, the models are constrained by estimates for the present-day areotherm. Third, we consider core thermal conductivity, kc, values in the range 5-40 W m(-1) K-1 as suggested by recent experiments on iron alloys at Mars core conditions. The majority of our models indicate that the core of Mars is fully conductive at present with core temperatures greater than 1940 K. All of our models are consistent with the range of k(c)=16-35 W m(-1) K-1. Models with an activation volume of 6 (0) cm(3) mol(-1) require a mantle reference viscosity of 10(19)-10(20)(10(20)-10(21)) Pa s.