顾及月表铁元素含量的次生撞击坑识别

在对月表地质单元定年时,由于月球岩石、土壤和岩心样品数量有限,能够利用这些样品做同位素定年的地质单元范围很小,因此更大范围的月球表面的绝对年龄需要采用撞击坑尺寸频率定年法(crater size-frequency distribution,CSFD)测定.然而月球表面次生撞击坑的存在会导致CSFD得到的定年结果出现偏...

Identification of Secondary Craters Based on Distribution of Iron Element on Lunar Surface

  Objectives  To determine the geologic age of the lunar surface is the foundation of the research on the formation and evolution of the Moon, and also the foundation of the inversion process of lunar geological events. Lack of lunar rock and soil samples limits the range of geological units that can be used for isotopic dating. Therefore, the dating using crater size-frequency distribution (CSFD) is employed to obtain the geologic ages of broader regions on the lunar surface. However, the presence of secondary craters will lead to a deviation in geologic age which is obtained by CSFD method. Thus, secondary craters should be eliminated to get a more accurate geologic age.  Methods  This paper presents a method to identify secondary craters based on the distribution of iron element on lunar surface. First, the method assumes that the iron content in secondary craters is close to that in lunar regolith. Then, band ratio method is utilized to acquire the iron content. Finally, secondary craters are distinguished from primary ones in terms of the difference of iron content between craters and lunar regolith.  Results  The effectiveness and robustness of the proposed method are tested by using the multispectral data obtained by multi-band imager of the Japanese Selene Mission. The experimental results show that the geologic age deviation compared with the known isotopic dated ones is less than 0.1 Ga, which shows good consistency.  Conclusions  Compared with other secondary craters identification methods, the proposed method is proven to be more effective and robust.