Earth core formation model ages

Core formation model ages for Vesta, Mars, Earth and Moon... 

The early history of Earth is greatly influenced by the probable impact of a Marssized body to form the Moon. Core-formation models suggest both Earth and the impactor were already differentiated by the time of the impact (Tonks Melosh 1992). The lack of a clear182W excess in uncontaminated lunar samples implies that the Moon-forming impact took place >50 Myr after the start of the Solar System (Touboul et al. 2007). The oldest known lunar samples are 150 Myr younger than CAIs, based on Sm-Nd dating (Touboul etal. 2007), which provides a lower limit on the Moon s age. 

The calculation of core formation ages based on Hf-W observations is strongly model-dependent. The W isotope evolution of Earth s mantle does not only depend on the timescale of accretion and core formation, but also on the degree of re-equilibration between the metal cores of newly accreted planetesimals, the W isotope composition in the mantles of the newly accreted objects, and on the mechanisms of accretion. Hence, Hf-W chronometry alone cannot... 

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