Title:
Oceans, Subduction and Granitic Crust on the Hadean Earth
Abstract:
The Hadean Eon (>4 Ga, 4 billion years ago) is Earth’s oldest and most mysterious time. Detrital zircons as old as 4.4 Ga are the only known relicts of granitic crust. Analysis of these tiny grains of sand yields evidence that the Hadean was not as “hell-like” as once imagined. Liquid water oceans were habitable and hydrous crust subducted, fluxing melting to form granitic magmas. Could there have been plate tectonics or life this early? Opinions vary. I haven’t seen compelling evidence, but many are looking.
