Abstract:

The northern land of the lunar Mare Imbrium is the second mountain ring around the Imbrium multiring basin, and the average elevation is about -1 km. Masses of the ejecta from Sinus Iridum and Crater Plato caused severely nonuniform elevation of this area, which is clearly shown by the DEM. The craters located in this area are counted and divided into four groups based on the depth/diameter ratios. The craters with less depth/diameter ratio and larger oblateness are regarded as older craters. The distributions of older craters are more close to the Mare. The mapping of lineaments in this area reveals three preferred orientations, i.e. EW, NEESWW and NW-SE direction. The style of lineament distribution is roughly matched with the Lunar Grid System and likely formed before the Imbrium event. These lineaments, including fractures and rills, had supplied tunnels for the intrusion of basaltic magma during the period of mare basalt flooding. Some intruded basaltic magma extruded onto the surface of this land in several places with lower elevations. The average content of FeO of extruded magma is close to but lower than that of mare basalt. The features of the geological structure and evolution history of this area were summarized, and it could be concluded that there do exist marelike lands on the Moon.

Key words: Lunar regional structure, Mare Imbrium, Sinus Iridum, Crater Plato, Change 1