Partial Atmospheric Loss and Partial Mantle Melting during the Giant Impact Stage of Planet Formation

Thursday, 18 December 2014: 5:15 PM
Sarah T Stewart1,2, Simon James Lock1 and Sujoy Mukhopadhyay2, (1)Harvard Univ, Cambridge, MA, United States, (2)University of California Davis, Davis, CA, United States
Mantle noble gas data record evidence for multiple partial mantle magma oceans and atmospheric loss episodes on the growing Earth. Based on a broad suite of giant impact simulations, we develop widely-applicable scaling laws for blowoff of the atmosphere and an ocean. In addition, we consider the early time energy budget to estimate the volume of mantle melted by a giant impact. For the specific impact energies typical of terrestrial planet formation, partial atmospheric blowoff is common when an ocean is present, but ocean loss is rare. Atmospheric blowoff without an ocean requires impact energies on the high end expected during planet formation. Impact-generated full mantle magma oceans are rare events and partial mantle magma oceans are expected. Both giant impacts and planetesimal bombardment contribute significantly to the evolution of volatiles on a growing planet. Because the giant impact stage is stochastic, different sequences of giant impacts lead to differences in the volatile content and interior thermal states of the final planet.