Isotopic constraints on the formation and evolution of the Earth-Moon system

Friday 28 February, 1:00pm
Seminar Rooms
fnimmo

Prof Francis Nimmo

UC Santa Cruz

Francis Nimmo's interests are the interiors and evolution of solid solar system bodies. He received his BA in 1993 and PhD in 1996, both from Cambridge University. He joined the faculty at UC Santa Cruz in 2005 and received the Macelwane medal and Urey prize in 2007. He served on the GRAIL, Cassini, New Horizons and InSight missions and is a member of four teams on Europa Clipper.  He was elected to the National Academy of Sciences in 2020 and the Royal Society in 2024.

 

Abstract

Isotopes are useful probes of planet formation and evolution for at least two reasons. Some exhibit nucleosynthetic anomalies providing clues to their original location. Others undergo decay, providing age constraints. In this talk, I'll discuss two applications of these ideas. The fact that the silicate Earth records different fractions of "carbonaceous" material in different elements implies that it experienced a change in the material it was accreting over time. The first ~95% was "non-carbonaceous", while the last ~5% was "carbonaceous" and volatile-rich. Reconciling these constraints with existing planetary accretion scenarios is not easy. In the second part, I'll discuss the idea that the pile-up of lunar ages around 4.35 Gyr is not the signature of magma ocean crystallization but is instead related to a tidal heating event. This story allows the Moon to be older (~4.45 Gyr or so), which is easier to reconcile with dynamical models.

Venue

Seminar rooms

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