Abstract:

The lunar landform is the result of the geological and geomorphic processes on the lunar surface. It is very important to identify the type of the lunar landforms. Geomorphology is the scientific study of the origin and evolution of topographic landforms on the planetary surface. Elevation and relief amplitude are the most commonly used geomorphic indexes in the study of geomorphological classification. Previous studies have determined the elevation classification criterion of lunar surface. In this paper, we focus on the classification criterion of the topographic relief amplitude of the lunar surface. As for the estimation of the best window to calculate the relief amplitude of the lunar surface, we used the method of change-point in the mean based on LOLA (Lunar Orbiter Laser Altimeter) DEM data and DEM that combines the LOLA and SELENE TC (Terrain Camera) merged Digital Elevation Model (SLDEM2015). According to the statistical analysis of the basic lunar landforms, the classification criterion of lunar surface relief amplitude is determined. Taking the topographic relief amplitudes of 100 m, 200 m, 300 m, 700 m, 1500 m and 2500 m as the thresholds, the lunar surface is divided into seven geomorphic types, including slightly micro-relief plains (< 100 m), slightly micro-relief platforms [100 m, 200 m), micro-relief landforms [200 m, 300 m), small relief landforms [300 m, 700 m), medium relief landforms [700 m, 1500 m), large relief landforms [1500 m, 2500 m) and extremely large relief landforms (≥ 2500 m). The slightly micro-relief plains are mainly distributed in the maria, and the floor of craters and basins that are filled with basalts, while the slightly micro-relief platforms are mainly distributed in the transition regions between the maria and highlands. The micro-relief landforms are mainly located in the regions with higher topography than the mare, such as wrinkle ridges and sinuous rilles in the mare. The small relief landforms are mainly scattered in the central peak and floor-fractured of craters. The medium relief landforms are mainly distributed in the transition regions between the rater floor and carter wall, between the crater wall and crater rim, between the basin floor and basin wall, and between the basin wall and basin rim. Large and extremely larger relief landforms are mainly scattered in the crater wall and basin wall. The determination of classification criteria of lunar surface relief amplitude in this paper can provide important references for the construction of digital geomorphology classification schemes of the lunar surface.

Key words: lunar geomorphological classification schemes, morphometric features, lunar relief amplitude, characteristics analysis, classification criteria