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Dating Volcanism on the Moon with LG-SIMS: U-Pb Analysis of Chang’E 5 Returned Samples – Application note

Friday, June 24, 2022

Crater-counting chronology has been widely used to date terrains on the Moon. The analyses of samples returned by the Apollo and Luna missions allowed scientists to anchor the chronology with absolute ages. In particular, they revealed a basaltic magmatism that occurred between 4.4 Ga and 2.9 – 2.8 Ga. But while crater-counting chronology suggested a more extended volcanism period (up to 1.2 Ga), no samples were returned to confirm those ages.

The Chinese sample-return mission Chang’E 5 landed specifically on young mare basalt units previously dated by crater-counting chronology at 1.2 to 2.1 Ga. Over 150 grains were analyzed by Large Geometry SIMS at Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS) Beijing. The obtained isochrons reveal a crystallization age of 2.030 ± 0.004 Ga for those young lunar basalts, bringing evidence that volcanism on the Moon existed until at least 2 Ga.