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Reconstructing the impact history of the Moon with the help of lunar zircon and phosphates

Thursday 10 September - 4 PM

Dr. Fiona Thiessen

ABSTRACT: Planetary bodies in our Solar System, including the Moon, were exposed to an intense asteroid bombardment between ~4.5-3.8 Ga, shaping their surfaces and leaving visible “footprints” in the form of large impact basins. Nevertheless, it is still controversial whether there was a cataclysmic increase in impacts around 3.9 Ga, the so-called Late Heavy Bombardment (LHB).

Therefore, in this study, impact breccias from different Apollo landing sites were investigated with the overall aim to gain a better understanding of the impact and magmatic history of the Moon. This endeavour included comprehensive textural and petrological analyses of the breccias and grains of interest (i.e. Ca-phosphates and zircon), as well as obtaining precise U-Pb Secondary Ion Mass Spectrometry (SIMS) ages. Future work will include EBSD analysis of zircon and phosphates. The combination of these methods will help to link U-Pb ages to real events (i.e. magmatic or impact related).