title: Widespread mixing and burial of Earth's Hadean crust by asteroid impacts.
abstract: The history of the Hadean Earth (∼4.0-4.5 billion years ago) is poorly understood because few known rocks are older than ∼3.8 billion years old. The main constraints from this era come from ancient submillimetre zircon grains. Some of these zircons date back to ∼4.4 billion years ago when the Moon, and presumably the Earth, was being pummelled by an enormous flux of extraterrestrial bodies. The magnitude and exact timing of these early terrestrial impacts, and their effects on crustal growth and evolution, are unknown. Here we provide a new bombardment model of the Hadean Earth that has been calibrated using existing lunar and terrestrial data. We find that the surface of the Hadean Earth was widely reprocessed by impacts through mixing and burial by impact-generated melt. This model may explain the age distribution of Hadean zircons and the absence of early terrestrial rocks. Existing oceans would have repeatedly boiled away into steam atmospheres as a result of large collisions as late as about 4 billion years ago.
authors: Southwest Research Institute, Boulder, Colorado 80302, USA.
authors: S
authors: S
authors: Marchi
authors: Southwest Research Institute, Boulder, Colorado 80302, USA.
authors: W F
authors: WF
authors: Bottke
authors: 1] Carnegie Institution for Science, Washington DC 20015, USA [2] School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287, USA.
authors: L T
authors: LT
authors: Elkins-Tanton
authors: Museum für Naturkunde, Berlin 10115, Germany.
authors: M
authors: M
authors: Bierhaus
authors: Museum für Naturkunde, Berlin 10115, Germany.
authors: K
authors: K
authors: Wuennemann
authors: Observatoire de la Côte d'Azur, Nice 06304, France.
authors: A
authors: A
authors: Morbidelli
authors: Universities Space Research Association, Lunar and Planetary Institute, Houston, Texas 77058, USA.
authors: D A
authors: DA
authors: Kring
mesh_terms: D003198:Computer Simulation; D018534:Earth, Planet; D049690:History, Ancient; D006358:Hot Temperature; D018543:Minor Planets; D008962:Models, Theoretical