Moon rocks brought to Earth by Chinese mission fill key gaps in solar system history

An exciting time now in lunar studies and dating. This report came out too. Samples returned by Chang'e-5 reveal key age of moon rocks, https://phys.org/news/2021-10-change-samples-reveal-key-age.html From the paper cited, Age and composition of young basalts on the Moon, measured from samples returned by Chang’e-5, https://www.science.org/doi/10.1126/science.abl7957, 07-Oct-2021.

"Abstract Orbital data indicate that the youngest volcanic units on the Moon are basalt lavas in Oceanus Procellarum, a region with high levels of the heat-producing elements potassium, thorium, and uranium. The Chang’e-5 mission collected samples of these young lunar basalts and returned them to Earth for laboratory analysis. We measure an age of 1963 ± 57 Ma for these lavas and determine their chemical and mineralogical compositions. This age constrains the lunar impact chronology of the inner Solar System and the thermal evolution of the Moon. There is no evidence for high concentrations of heat-producing elements in the deep mantle of the Moon that generated these lavas, so alternate explanations are required for the longevity of lunar magmatism."..."The emplacement age of 1963 ± 57 Ma that we infer for the Em4 unit provides a calibration point for the lunar crater size-frequency distribution (CSFD) chronology curve, which was previously unconstrained between ~1 and 3 Ga (Fig. 4) (5, 21). This age for Em4 falls below many existing crater chronology curves, indicating that the impact flux may have been lower than previously estimated at ages between the youngest Apollo-Luna basalts (~3.1 Ga) and that inferred for the Copernicus crater (~0.8 Ga), consistent with some chronology models (22, 23). N(1), the number density of 1 km craters, on the Em4 unit (1.24×10^−3 to 1.74×10^−3 km^−2) is similar to the upper limit measured for the Copernicus crater [(23, 24); Fig. 4], so Copernicus might be older than the ~0.8 Ga radiometric age inferred from the glasses sampled by Apollo 12 (25)."

Interesting reading the reports on how the Moon is dated. If these new lunar samples were the only rocks from the Moon, the lunar crater dating likely would be very different than what developed from the Apollo samples. My observation. Dating the Moon is not an easy job. Different lunar samples from Apollo and the Chinese mission show different radiometric ages. Copernicus crater dated near 0.8 x 10^9 years old, these new Chinese lunar rocks date near 2 x 10^9 years old, and the Moon's age is considered to be close to 4.5 x 10^9 years old. Dating when Theia impacted the proto-earth to create the Moon is another issue along with how long the Moon remained a magma ocean, some models indicate 200 million years so the solid Moon likely formed near 4.3 billion years ago according to those models.
 
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