A New Method for the Identification of Lunar Cryptomaria and Their Analysis in the Schiller‐Schickard Region

Abstract

AbstractCryptomaria play critical roles in elucidating the early thermal history of the Moon. In contrast with traditional dark halo impact crater (DHC) identification methods, this study focused on exposed rock (0.5%–29.54% rock abundance) surfaces as windows for cryptomare identification. We classified the lithology of these rock surfaces to find those that match mare basalt using major element oxide products based on data from the Diviner instrument aboard the Lunar Reconnaissance Orbiter (LRO) and by Lunar Prospector thorium products, in accordance with laboratory lithological classification criteria. Then, by combining the locations of 0.5%–29.54% rock abundance values with the lithologies, we created a map of exposed basaltic rock surfaces and 14 cryptomare candidate regions with dozens of closely spaced basaltic rock pixels were identified across the Moon. Among 14 candidate regions, 11 cryptomaria were consistent with results in literature (Whitten & Head, 2015a; https://doi.org/10.1016/J.ICARUS.2014.09.031) based on DHCs, and 3 cryptomaria were newly identified. In the Schiller‐Schickard region, we refined the boundaries of 18 individual cryptomare units using our rock analysis combined with LRO color shaded relief maps. A detailed analysis of the distribution, composition, area, depth, thickness, and volume and the morphological features of these 18 identified cryptomare units indicates that the basalt materials covered by the Orientale basin or other impact crater ejecta display variable thicknesses and discontinuous layers. These identified cryptomare units and their morphological features provide information on regional stratigraphy as well as on the thermal evolution of the Moon.