Thermal effects of core formation in planet Earth

The paper discusses thermal effects of core formation in the early Earth, during the late stages of planetary accretion. Numerical calculations of the evolution of the temperature distribution T(t,r) in the growing core are presented. Surprisingly, the computations show a thermally stable core at the end of the Earth's formation, i.e. the temperature distribution is 'adverse', that means δT/δr > 0 and there is no thermal convection. This contradicts palaeomagnetism, but the calculations base on widely accepted scenarios of accretion and core formation. Several possibilities to circumvent these complications are discussed, especially the influence of late heavy impacts of planetesimals on the growing Earth. Giant 'planetesimals' with a radius of 1000 km or more, probably release enough energy to change the whole preceding thermal history of the Earth. (author)