Evidence of 4.3 Ga Mg‐Suite Magmatism in the Western Procellarum KREEP Terrane Provided by Zircon From Chang'e‐5 Regolith

Abstract The formation of Mg‐/Alkali‐suites represents the most pronounced and oldest process in the magmatic evolution of the Moon. Fragments of these rocks have been identified among the samples collected by almost all lunar missions. In addition, remote observations indicate widespread distribution of these rocks on the Moon. However, collected samples remain restricted to the locations around the south‐eastern boundary of the Procellarum KREEP Terrane (PKT), limiting the ability to confirm information provided by remote observations and to investigate relationships between Mg‐/Alkali‐suites in different parts of the Moon. An important feature of these rocks delivered by Apollo missions is enrichment in incompatible elements, resulting in a frequent appearance of accessory zircon, which can be considered as one of the identifiers of rocks belonging to these suites. Consequently, the age of 4,311 ± 35 Ma and chemical characteristics of a zircon grain found in an agglutinate from Chang'e‐5 soil are interpreted as evidence of an origin in an Alkali or most likely Mg‐suite rock. The zircon grain is exotic to the landing site surrounded by the young ca. 2.0 Ga basaltic flows and was most likely delivered to the site as a distal impact ejecta. The location of the collected sample at the Chang'e‐5 landing site to the west of the Imbrium basin, remote from all other sample collection sites, confirms the wide distribution of Mg‐suite rocks, at least within PKT. The age of the zircon also provides the first indication that this early magmatism could have been contemporaneous across the nearside of the Moon.