The Chang’E-5 basalts are thus the youngest dated Moon rocks and they extend the duration of mare volcanism 800–900 million years longer than previously known ( Figure 1A). Irrespectively, the two independent laboratories in Beijing arrived at indistinguishable ages within uncertainty. 3 Zirconium-bearing minerals were only <5 μm wide, thus the ∼3-μm spot size of one study, 3 compared with ∼7 μm in the other, 2 also provided additional accuracy by avoiding terrestrial, laboratory-derived Pb contamination along grain boundaries. The age on Zr-rich minerals from the Science study 2 agrees well with the robust 2,030 ± 4 Ma age. The second study reporting Chang’E-5 geochronology, published in Nature 3 on October 19 th, yielded a strikingly precise age of 2,030 ± 4 Ma based on 51 grains of Zr-rich minerals from 47 rock fragments. The first geochronology study of Chang’E-5 was published in Science 2 on October 7 th and reported two types of ages: one age (1,963 ± 57 million years ago ) is based on 18 analyses of two rock fragments the other age (2,011 ± 50 Ma) relies exclusively on Zr-bearing minerals ideal for dating due to U enrichment with negligible non-radiogenic Pb (lunar initial Pb). Two geochronology studies have been conducted on the Chang’E-5 basalts, both employing the Pb-Pb isochron method ( 204Pb/ 206Pb versus 207Pb/ 206Pb), which has proven reliable in the study of Apollo basalts. However, as with any new data, as some questions are answered, new ones always arise. How long did mare volcanism last, and, if volcanic activity persisted quite late in lunar history, what was the Moon's secret to a longer life? These are the questions that the Chang’E-5 samples, the first lunar samples returned to Earth in 44 years, can begin to answer.
It was first critical to establish, as published in National Science Review, 1 that the samples collected by Chang’E-5 from the highly impacted lunar regolith indeed had compositional affinity to mare basalts. Based on crater counting chronology (see below), the selected landing site targeted potentially some of the youngest rocks on the Moon ( Figure 1B). In (B)–(C), landing sites are indicated with dots for Apollo (light blue) and Luna (dark blue).Ĭhina's Chang’E-5 mission thus sought a new frontier: discover the younger rocks on the Moon to see what they could reveal about the longevity of lunar geologic activity.
In (A)–(C), red dots indicate the age and location of Chang’E-5. Any volcanism after 2 Ga is highly localized.Ĭratering ages (B) and thorium contents (C) of mare basalts.
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