New Insights Into Lithology Distribution Across the Moon

摘要

abstract_textpLithology distribution across the Moon is pivotal for understanding lunar evolution. However, so far, the distribution of lunar rock suites is still uncertain; as a result, many related core issues on lunar evolution have long been in dispute. This work reports on a new lithology distribution map across the Moon and discusses some critical issues of the lunar evolutionary process. The oxide abundances derived from Chang'E-1 Interference Imaging Spectrometer imagery and the Th contents inferred by Lunar Prospector Gamma Ray and Neutron Spectrometer data are employed to generate the lithological map by using the decision tree C5.0 algorithm. The following conclusions are inferred from this new map. (1) Magnesian suite is widely distributed across the Feldspathic Highlands Terrane and in the periphery of the South Pole-Aitken Terrane. Thus, the viewpoints have been validated that the early magnesian magmatism may be a global phenomenon and that KREEP basalt is not necessary for the petrogenesis of Mg-rich rocks. Moreover, the regions of Dryden, Chaffee S, Theophilus, and Moscoviense are confirmed as magnesian suite exposures. (2) The observation that the Feldspathic Highlands Terrane has a higher Mg/(Mg + Fe) value than the maria is related to the flood of the Mg suite across the Feldspathic Highlands Terrane. (3) The specific exposed locations of the alkali suite across the Moon have long been unsolved, and this work discloses that the alkali suite prevails in the outskirts of the Procellarum KREEP Terrane, the center of the South Pole-Aitken Terrane, and some isolated locales. (4) Focusing on distinguishing mare basalts from other mafic rocks, seven geochemical indices are proposed to determine the potential exposures of mare basalts across the Moon. (5) In Mare Insularum, a series of KREEP volcanisms may have occurred and lasted longer than the mare volcanism./ppPlain Language Summary Lithology distribution across the Moon is pivotal for understanding lunar formation and evolution. However, so far, the distributions of lunar rock suites have remained uncertain. As a result, many related core issues on lunar evolution have long been in dispute. This work reports on a new map of lithology distribution across the Moon. Based on the new insights into the lithology distribution across the Moon, this work suggests answers to some unsolved or uncertain critical issues: (1) What are the potential distributions of magnesian and alkali suites across the Moon? (2) Is the observation that the Feldspathic Highlands Terrane has a higher Mg/(Mg+Fe) value than the maria related to the exposures of magnesian suite? (3) Where are the potential exposures of mare basalts on the lunar surface? (4) In Mare Insularum, had KREEP volcanism or mare volcanism lasted longer? (5) Did the early magnesian magma globally or locally invade into the feldspathic crust?/p/abstract_text