基于最优分割分级法的月球撞击坑分级及其演化分析

The grading and evolution analysis of lunar crater based on optimum partition and grading method

撞击坑是月球表面广泛分布的重要构造形态,占据了月球表面的大部分面积。撞击坑的直径差别很大,从几微米到数百千米,其退化程度与形成年代具有密切关系。为了研究不同地质年代形成的撞击坑直径大小及其演化规律,需采用量化分级方法对大小不同的撞击坑进行定量分级和统计分析。本文在月表撞击坑数据库LU60645GT和Lunar_Impact_Crater_Database(2011)的基础上,结合数据库中撞击坑的直径、深度和年代信息,利用最优分割分级法对撞击坑直径进行定量化分级,并根据分级结果,综合分析撞击坑几何形态特征及其演化规律。研究结果表明,撞击坑形态特征的演化与年代有密切的关系。在相同级别、相同地体下,撞击坑形成的年代越早,其形态特征的精细结构退化程度越明显,只保留了大体的几何形状;而在不同级别、相同地体、相同年代下的撞击坑形态特征则由简单逐渐变为复杂,坑物质也逐渐变得复杂。

Impact craters are the widespread units on the moon, which occupy most area of lunar surface. The diameter of craters is different from each other and varies from micrometers to hundreds of kilometers, and its degradation degree has a close relationship with age. In order to study the crater diameter and its evolution history, a quantitative grading method to classify the large variety of craters is needed. Combining with diameter, depth information of lunar crater database LU60645GT and age information of Lunar_Impact_ Crater_Database （2011） , we use optimum partition and grading method to classify the craters and make quantitative statistics of its morphological parameters. Based on the grading results, we analyze the morphological features and evolution history of crater. The results show that the evolution of crater is related to the age. At the same grade and same terrane, the earlier crater formed, the fine- scale texture of crater would be more obvious. But at different grades, same terrane and same age, the morphological characteristics of crater become complex gradually and the structure of crater also gets complicated.