Slopes of Lunar Crater Size‐Frequency Distributions on Exterior Impact Melt Deposits of Young Craters

Abstract Lunar impact craters can be used as a tool to derive information about the timing and sequence of the emplacement of geologic units and surface processes on the Moon. The production function (PF) derived from crater size‐frequency distribution (CSFD) measurements is an essential component in determining the model age of a geologic surface. The PFs of Neukum (1983) and Neukum et al. (2001), https://doi.org/10.1007/978‐94‐017‐1035‐0_3 are defined only over a crater diameter range between 10 m and 300 km and are among the most frequently used PFs. However, a potential extension of the valid crater diameter range to smaller craters may be possible due to the availability of high‐resolution image data, and a larger number of small craters could reduce the statistical errors in age determinations. To evaluate whether CSFD measurements with craters ≤10 m are suitable for inclusion in a PF, we complement the investigation of ejecta blankets (Oetting et al., 2023, https://doi.org/10.1029/2023je007816 ) by analyzing the CSFD slopes of small craters formed on impact melt deposits of young Copernican‐aged craters Tharp, Korolev Z, Thales, and Glushko. The resulting CSFD slopes are slightly steeper for craters between 10 and 20 m than the proposed cumulative −3 slopes by Neukum (1983) and Neukum et al. (2001), https://doi.org/10.1007/978‐94‐017‐1035‐0_3 . The CSFD slope for craters ≤10 m is shallower than −3. In this study, the CSFD slopes are derived from unbinned data, but we present our CSFD measurements in both unbinned and binned form. Our results indicate that small crater diameters (≤10 m) can be included for extending a PF.