Earth's wild years: The role of impact processes

Abstract

In the aftermath of the giant collision resulting in the formation of the Moon, about 4.5 billion years ago, the Earth experienced a protracted bombardment by leftover planetesimals. In this talk, I will present a bombardment model of the Hadean Earth (4.5-4.0 Ga) that has been calibrated using existing lunar and terrestrial data. This model shows that the near-surface of the Hadean Earth was widely reprocessed through mixing and burial by impact-generated melt. Further, I will discuss the effects of early collisions on the formation of impact-induced geochemical heterogeneities that could still persist in terrestrial mantle rocks. Finally, I will present a recent impact model for the Archean Earth (4.0-2.5 Ga), and discuss implications for the oxygenation history of Earth’s atmosphere.

Bio

Dr. Simone Marchi’s research interests include the formation and evolution of terrestrial planets, the Moon and asteroids. He is associate with several space missions, including: NASA’s Dawn, Lucy, Psyche, and ESA’s Rosetta, BepiColombo, JUICE.

He has recently published a trade book, Colliding Worlds: https://global.oup.com/academic/product/colliding-worlds-9780198845409?

More details can be found here: http://www.boulder.swri.edu/~marchi/index.html