Abstract
We will present the Hf-W radioactive clock, used to date the differentiation of planetary bodies, and apply it to Mars and Earth, revealing radically different accretion times. However, the complex history of Earth’s accretion, marked in particular by the role of giant impacts, makes interpreting this clock challenging. The use of a second clock, the U-Pb system, provides additional constraints. Dating the Moon is particularly important for constraining the end of Earth’s formation. While the Sm-Nd clock seems to indicate that the Moon formed approximately 200 million years after the Solar System’s inception, other clocks, such as Lu-Hf or Rb-Sr, suggest a much earlier formation, approximately 50 million years after its inception. We will see how this discrepancy can potentially be explained.
