  Recent high precision meteoritic data improve constraints on the formation
timescale and bulk composition of the terrestrial planets. High resolution
N-body simulations allow direct comparison of embryo growth timescale and
accretion zones to these constraints. In this paper, we present results of high
resolution simulations for embryo formation from a disc of up to 41,000
fully-self gravitating planetesimals with the GPU-based N-body code GENGA. Our
results indicate that the growth of embryos are highly dependent on the initial
conditions. More massive initial planetesimals, a shorter gas disc decay
timescale and initially eccentric Jupiter and Saturn (EJS) all lead to faster
growth of embryos. Asteroid belt material can thereby be implanted into the
terrestrial planet region via sweeping secular resonances. This could possibly
explain the rapid growth of Mars within 10 Myr inferred from its Hf-W
chronology. The sweeping secular resonance almost completely clears the
asteroid belt and deposits this material in the Mercury-Venus region, altering
the composition of embryos there. This could result in embryos in the
Mercury-Venus region accreting an unexpectedly high mass fraction from beyond 2
AU. Changing the initial orbits of Jupiter and Saturn to more circular (CJS) or
assuming embryos formed in a gas free environment removes the sweeping secular
resonance effect and thus greatly decreases material accreted from beyond 2 AU
for Mercury-Venus region embryos. We therefore propose that rock samples from
Mercury and Venus could aid greatly in deducing the condition and lifetime of
the initial protoplanetary gas disc during planetesimal and embryo formation,
as well as the initial architecture of the giant planets.
