Destabilization of Long-Lived Hadean Protocrust and the Onset of Pervasive Hydrous Melting at 3.8 Ga

Drabon, N., Byerly, B.L., Byerly, G.R., Wooden, J.L., Wiedenbeck, M., Valley, J.W., Kitajima, K., Bauer, A.M., Lowe, D.R., 2022. Destabilization of Long‐Lived Hadean Protocrust and the Onset of Pervasive Hydrous Melting at 3.8 Ga. AGU Advances, 3(2). https://doi.org/10.1029/2021AV000520 

Detrital zircon trace and rare earth element geochemistry as well as Hf and O isotopes were investigated from a new Hadean locality, containing 4.1-3.3 Ga detrital zircons from the 3.31 Ga Green Sandstone Bed, Barberton Greenstone Belt. Zircons older than 3.8 Ga show evidence for a long-lived protocrust with a relative absence of juvenile additions to zircon-bearing magmas, whereas after 3.8 Ga zircon Hf isotopes indicate a more muted protocrust signal with evidence for relatively juvenile melt components. These results mirror results from other Archean terranes and indicate a global onset of crustal instability and recycling between 3.6 and 3.8 Ga, with implications for the formation of early Earth crust and onset of plate tectonics.