  Recent high precision meteoritic data infers that Mars finished its accretion
rapidly within 10 Myr of the beginning of the Solar system and had an accretion
zone that did not entirely overlap with the Earth's. Here we present a detailed
study of the accretion zone of planetary embryos from high resolution
simulations of planetesimals in a disc. We found that all simulations with
Jupiter and Saturn on their current eccentric orbits (EJS) result in a similar
accretion zone between fast-forming Mars and Earth region embryos. Assuming
more circular orbits for Jupiter and Saturn (CJS), on the other hand, has a
significantly higher chance of forming Mars with an accretion zone not entirely
dominated by Earth and Venus region embryos, however CJS in general forms Mars
slower than in EJS. By further quantifying the degree of overlap between
accretion zones of embryos in different regions with the average overlap
coefficient (OVL), we found that the OVL of CJS shows a better match with the
OVL from a chondritic isotopic mixing model of Earth and Mars, which indicates
that the giant planets are likely to have resided on more circular orbits than
today during gas disc dissipation, matching their suggested pre-instability
orbits. More samples, including those from Mercury and Venus, could potentially
confirm this hypothesis.
