  The meteorite sample Erg Chech (EC) 002 is the oldest felsic igneous rock
from the Solar System analysed to date and provides a unique opportunity to
study the formation of felsic crusts on differentiated protoplanets immediately
after metal-silicate equilibration or core formation. The extinct 53Mn-53Cr
chronometer provides chronological constraints on the formation of EC 002 by
applying the isochron approach using chromite, metal-silicate-sulphide and
whole-rock fractions as well as "leachates" obtained by sequential digestion of
a bulk sample. Assuming a chondritic evolution of its parent body, a 53Cr/52Cr
model age is also obtained from the chromite fraction. The 53Mn-53Cr isochron
age of 1.73 (+/-) 0.96 Ma (anchored to D'Orbigny angirte) and the chromite
model age constrained between 1.46 (-0.68/+0.78) and 2.18 (-1.06/+1.32) Ma
after the formation of calcium-aluminium-rich inclusions (CAIs) agree with the
26Al-26Mg ages (anchored to CAIs) reported in previous studies. This indicates
rapid cooling of EC 002 that allowed near-contemporaneous closure of multiple
isotope systems. Additionally, excess in the neutron-rich 54Cr (nucleosynthetic
anomalies) combined with mass-independent isotope variations of 17O provide
genealogical constraints on the accretion region of the EC 002 parent body. The
54Cr and 17O isotope compositions of EC 002 confirm its origin in the
"non-carbonaceous" reservoir and overlap with the vestoid material NWA 12217
and anomalous eucrite EET 92023. This indicates a common feeding zone during
accretion in the protoplanetary disk between the source of EC 002 and vestoids.
The enigmatic origin of iron meteorites remains still unresolved as EC 002,
which is more like a differentiated crust, has an isotope composition that does
not match known irons meteorite groups that were once planetesimal cores.

Earth and Planetary Astrophysics;Geophysics