Abstract
AbstractThe impact melt that records the formation time of basins is essential for the understanding of the lunar bombardment history. To better understand melt distribution on the Moon, this study investigates mixing of melt by small impacts using a Monte Carlo numerical model. The obtained mixing behavior is then integrated into a larger scale model developed in previous work. While large impacts produce most of the melt volume in both the regolith and megaregolith, we find that the dominant source of melt near the surface is small impacts. Material in the top meter is affected mainly by impacts that form craters <5 km in diameter. In the uppermost 10 cm, melt with age <0.5 Ga is abundant; while as depth increases older melt is increasingly present. This may indicate that the excess of impact melt <0.5 Ga in lunar samples from the near surface is caused by the cumulative mixing of small impacts. A comparison of the age distribution of melt derived from craters of different sizes with that of impact glass constrains the size of spherule‐forming impacts. Our model is consistent with observations if most impact glass spherules from the near surface are produced by <100 m craters and >100 m craters do not contribute abundant spherules. The distribution of the datable melt with depth is also analyzed, which is essential for future sampling missions. Excavated materials of young and large craters (>100 m on highlands; >10 km on maria) appear to be the most fruitful targets.
Highlights
Impact melt products of known provenance are the key to unveiling the bombardment history of the Moon (Morbidelli et al, 2018; Stöffler, 2006; Zellner, 2019)
To better understand melt distribution on the Moon, this study investigates mixing of melt by small impacts using a Monte Carlo numerical model
In the uppermost 10 cm, melt with age
Summary
Impact melt products (melt rocks and glasses) of known provenance are the key to unveiling the bombardment history of the Moon (Morbidelli et al, 2018; Stöffler, 2006; Zellner, 2019). The melt diffusion in megaregolith caused by large impacts was investigated by Liu et al (2020) based on their developed numerical model In their model, with the knowledge of lunar impact flux, the formation sequence of differently sized craters was calculated. To understand the melt distribution over some regional areas that were distinctly affected by the larger crater during the late period, the additional simulations where the thick ejecta cover the study region at various times during the formation of small craters have been performed (Section 3.2)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
