Applying these methods to the Chang’e-5 basalts and compiling previous results of eruptive flux throughout lunar history, we are able to identify that, despite its long-term secular cooling, the Moon was still capable of significant pulses of magmatism at about 2 Ga.Ĭrystal classification and chemical zoning Extrapolated timescales can be used to estimate the thickness and volume of basaltic lava flows 22, 23. An effective method is to determine post-eruption lava flow cooling timescales using diffusion chronometry, which models diffusive relaxation of compositional boundaries within zoned minerals 18, 19, 20, 21. The 2-billion-year-old Chang’e-5 basalts from the northeastern Oceanus Procellarum terrane 5, 6 provide a unique opportunity for this. Here, we focus on using the chemical compositions and zoning patterns in olivine and clinopyroxene crystals from a large set of Chang’e-5 basalts with different textures to reconstruct their thermal history, estimate volcanic fluxes on the Moon, and discuss the implications this has for the most recent volcanism on the Moon. 14, 15) (ii) difficulties in the recognition of flow fronts caused by impact bombardment and other continuous erosional processes 16 and (iii) estimating the volume of a mare unit of a certain age, which is limited by insufficient knowledge of crater scaling laws and/or empirical equations of crater morphology 17. 11, 12, 13), there are several complications, including: (i) the large uncertainties in crater counting chronology between 3 and 1 Ga (refs. Although previous studies using remote sensing data investigated volcanic flux for young volcanic activity (<2.8 Ga refs. Knowledge of the eruptive fluxes in terms of volume/mass could place constraints on this late-stage lunar volcanic activity. However, recent studies of samples returned from the Chang’e-5 mission directly date lunar volcanism to 800–900 million years (Myr) 5, 6 later than previously measured in returned samples and meteorites 7, 8, where heat-producing elemental and water concentrations were lower than expected 6, 9, 10, thus challenging the common view of lunar magmatism and thermal evolution of the Moon. Such a duration of basaltic volcanism on the Moon is broadly consistent with models of thermal evolution 3, 4. Mare volcanism was most pronounced about 3.8–3.3 billion years ago (Ga) and then declined or disappeared by 2.9–2.8 Ga, as shown by the age distribution of the Apollo, Luna, and meteorite collections 2. There is agreement that volcanic activity on the Moon is temporally and spatially tied to the heat-producing elements 1, unlike magmatic systems on Earth where more factors such as crustal recycling can trigger volcanic eruptions. Thermal modeling used to estimate the thickness and volume of the volcanism sampled by Chang’e-5 reveals enhanced magmatic flux ~2 billion years ago, suggesting that while overall lunar volcanic activity may decrease over time, episodic eruptions at the final stage could exhibit above average eruptive fluxes, thus revising models of lunar thermal evolution. Most olivine grains record a short timescale of cooling. We find that almost all of them are normally zoned, suggesting limited magma recharge or shallow-level assimilation. Here, we investigate the mineralogy and geochemistry of 42 olivine and pyroxene crystals from the Chang’e-5 basalts. The Chang’e-5 mission returned the youngest lunar basalts thus far, offering a window into the Moon’s late-stage evolution. However, young volcanic eruptions are poorly constrained by remote observations and limited samples, hindering an understanding of mare eruption flux over time. The history of mare volcanism critically informs the thermal evolution of the Moon.
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