1), at the base of the Sculptured Hills on the southeastern edge of the Serenitatis Basin 23, and are some of the most extensively studied samples from the Moon. The norites were sampled at Station 8 in Taurus-Littrow Valley (Supplementary Fig.
The Apollo 17 samples, 7826, are intrusive highlands rocks, compositionally defined as norites of the so-called magnesian-suite that were emplaced very early during lunar crust formation (~4.3–4.4 Gyr) 22. Most Apollo 17 samples are impact-melt breccias initially identified as originating from the Serenitatis Basin 20, but more recent studies 12, 21 have associated these breccias with Imbrium formation (~3.8–3.9 Gyr).Īs the oldest components of the lunar crust, the highlands samples record the earliest lunar evolution and cratering history. However, no lunar sample has ever been identified, which could provide a direct support to this hypothesis. Recent arguments have revived the interpretations of its ancient (~4.1–4.3 billion years, Gyr) age 2, 12, 13. Essentially, an ancient age of Serenitatis Basin would support the idea of protracted bombardment period 2, 4, 5, 11, 16, 17, 18, 19, and cast into doubt the onset and duration of the classical, spike-like LHB 5. Whether the Serenitatis Basin formed during the classical LHB has been a matter of debates for decades 2, 7, 12, 13, 14, 15. Closely linked to this topic is the timing of formation of the Serenitatis Basin-one of the largest and the oldest impact basins on the Moon (Supplementary Fig. Direct constraints on the timing and duration of the impact bombardment can be provided by absolute ages of the most ancient lunar surfaces and basins 7.
One of the outstanding questions in planetary science is the exact timing and duration of impact bombardment to the inner Solar System, including the purported Late Heavy Bombardment (LHB) 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11.
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