On December 16, 2020, the Chang’e 5 capsule carrying nearly two kilos of samples, bringing China into the top 3 countries that brought moon rocks to Earth. In a recent article in , an international team, led by Xiaochao Che, presents the first results concerning these samples.
The importance of dating new lunar samples
Chang’e 5 had landed in the middle of a region called Ocean of Storms, a huge basalt plain that researchers suspected to be relatively young. The aim of the mission was therefore to recover basalt samples in order to be able to date them and know their composition. The interest of this study is twofold: to define the absolute age of the basalts in this region in order to refine the chronology of lunar impacts, and to determine the origin of this (relatively) recent magmatism.
Knowing the age of these rocks is an important consideration, to say the least. You should know that on the Moon, the dating of surfaces is usually done by chronology of lunar impacts. The Moon is indeed a body without erosion, which implies that the traces of meteorite impacts are not gradually erased as on Earth, unless they are destroyed by a new impact or covered by a lava flow.
, the density of craters in a region therefore reflects the time elapsed since the formation of the ground: the higher the density of craters, the older the lunar surface in this region, and vice versa. This method makes it possible to establish a relative chronology of surfaces. The correlation with the ages of the samples brought back to Earth by the different missions then makes it possible to obtain an age / crater density relationship. This…
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