 These zircon xenocrysts originally crystallized in a granitic magma of crustal origin.Further evidence suggests that the 3.94 Ga tonalitic gneisses are at least partly derived from this 4.2 Ga granite magma, which indicates that crustal reworking was an important process in the Eoarchean.Zircons from this granite protolith shows similarities to zircons from the Yilgarn Craton in Western Australia, and may be evidence for continental crust forming in the Hadean Eon.