2017 Geology Colloquium Series
Friday, September 1st 2017 at 3:00 pm
in PLS 1130, the University of Maryland at College Park
NASA Goddard Space Flight Center
The Violent Early Solar System, as Told by Planetary Sample Geochronology
One of the legacies of the samples collected by the Apollo and Luna missions is the link forged between radiometric ages of rocks and the timing of major geologic events, such as impact cratering. Our current understanding of the chronology of the inner solar system is based on the Moon, where evidence suggests that intense bombardment happened during planet formation, followed by a relatively quiescent period, and increased again in an extraordinary bombardment event (“cataclysm”) in the Earth-Moon system at ~3.9 Ga. The importance of the age of lunar samples goes far beyond assigning stratigraphic markers to lunar chronology. The temporal evolution of lunar bombardment is tied to the evolution of a habitable Earth, while the flux of impactors at the Moon drives dynamical models of the formation of the inner solar system. Dr. Cohen will discuss how we use the geochronology of lunar and meteorite samples to understand the past history of impact events on the Moon, the Earth, and throughout the solar system.