Abstract:

The crust of Moon that has undergone little to none tectonic, atmospheric, or fluvial activity, is blanketed by the ubiquitous surface soil, or regolith, and there is hardly any bedrock exposed. It is produced from billions of years of physical and chemical weathering and exposure to the solar wind. These processes tend to blend and obscure the lithology of true crustal bedrock. So it is hard to detect the characteristics of the underlying basalts using conventional remote sensing methods. The key to the determination of true crustal compositions is to look beneath the obscuring regolith. This paper analyzes the spectra of the floor and wall in craters which have the low optical maturity to study the compositions and information (depth, succession and distribution) of the underlying basalts in Chang
’E-3’s landing area. The details are as follows: (1) selecting craters and extracting spectra based on multiband remote sensing data of LISM, (2) defining the types and determining the information of the basaltic units and building the relationships between discrete craters and the continuous geological unit. The results show that there are at least six basaltic filling processes in the study area, and we can define six basaltic units from young to old age. The depth of unit 13 is reduced gradually from south to north until disappears. The unit 46 may exist in all study area, and in south region they are covered by the first three basaltic units and not exposed, while in north region they are located at the top of the underlying basalts. As to the element abundances of all basaltic units, titanium content changes a lot, from 1.26% to 6.65%, while iron content shows small change, between 16.31% and 17.57%. Finally, we found that there is a link between basaltic unit age and element abundance, that is the younger the age of basaltic units, the more enrichment in titanium and iron in it.

Key words: Chang’E-3, landing area, underlying basalts, basaltic unit classification, filling process