Crustal Formation in the Hadean

Surface conditions were initially hostile on Earth as the planet was covered by a magma ocean and frequently struck by giant meteorites. The question remains: When did Earth become habitable? The lack of a rock record from Earth’s first 600 Ma of history has hindered our understanding of crust formation and only detrital zircon from that period provide a direct record of those early events. Until recently, our understanding of the Hadean was mainly based on a single location with abundant Hadean zircon, the Jack Hills region in Western Australia. I’m part of a group of researchers that recently discovered a new location of abundant Hadean detrital zircon in the Green Sandstone Bed (GSB) in the 3.6 to 3.2 Ga Barberton greenstone belt (BGB), South Africa (Byerly et al., 2018). Unlike the well-known Jack Hills locality, the GSB experienced low metamorphic grade (lower greenschist), is largely unstrained, and open to study from the micron- to the outcrop-scale.