See more from this Division: Topical Sessions
See more from this Session: Planetary Pummeling: Cataclysmic Bombardment of the Solar System as Catastrophe, Catalyst, Cauldron, and Crucible
Abstract:
Relating lunar surface deposits to specific basins is critical for assessing the reality (or otherwise) of the lunar cataclysm. Only Apollo 17 sampled a geologically well-defined impact-melt unit that can be linked with confidence to a major basin (Serenitatis). The concept of a LHB is critically tied to the age of Nectaris, one of the older nearside basins. Since the early 1980's consensus favored an origin of the Apollo 16 Descartes Formation as Nectaris ejecta, such that the ~3.9 Ga ages of Descartes breccia clasts were considered as strong support for a LHB. Recent high-precision dating of these breccias, however, established an age that is identical with Imbrium and younger than Serenitatis. As Nectaris is stratigraphically older than Serenitatis, this pulls the pin on the absolute age of Nectaris and removes one of the key arguments supporting a lunar cataclysm. Future lunar explorers face the difficult but necessary task of establishing the absolute ages of lunar basins in order to test the late cataclysm hypothesis.
See more from this Division: Topical Sessions
See more from this Session: Planetary Pummeling: Cataclysmic Bombardment of the Solar System as Catastrophe, Catalyst, Cauldron, and Crucible