Structure of differentiated planetesimals: A chondritic fridge on top of a magma ocean

Meteorites are interpreted as relics of early formed planetary bodies, and they provide information about the processes that occurred in first few Myrs our solar system. The ages measured for some differentiated meteorites (achondrites), indicate planetesimals a silicate crust ≈3Myr after beginning composition recently discovered achondrite Erg Chech 002 (EC002), oldest andesitic rock known so far, betokens partial melting chondritic source taking place ≈1Myr before all other achondrites. However, thermal models accreted predict massive planetesimal during core/mantle differentiation cannot account preservation substantial amount material. In this paper, we propose way to interpret petrological geochemical constraints provided by introducing refined model formation evolution. We demonstrate continuous, protracted accretion cold undifferentiated material upon magma ocean over timescale 2 times larger than lifetime 26Al heat leads km thick crust. During accretion, released radioactive decay further induces episodes at base crust, which can led rocks such EC002. Using available on age EC002 its cooling rate, application terminal radius parent body between 70 130km.