月球撞击坑辐射纹的形成和消失机制及可能的年代学应用

辐射纹是年轻撞击坑周缘呈辐射状分布的明亮细条纹，是月表最显著的地貌特征之一，也是月球科学领域热点研究之一。根据目前对于月球撞击坑辐射纹的形成和类型的认识，分析辐射纹消失相关的空间风化、撞击导致的物质混合等地质过程; 比较不同形成年龄撞击坑辐射纹的光学成熟度（OMAT）剖面，发现溅射物逐渐成熟过程中OMAT剖面的演变过程，撞击坑辐射纹OMAT剖面可采用幂函数描述；OMAT剖面形态参数与溅射物暴露年龄（撞击坑形成年龄）有很强的相关性。利用已知年龄且存在辐射纹的撞击坑为参考点，建立辐射纹OMAT形态参数与撞击坑形成年龄的经验关系，提出了约束撞击坑形成绝对年龄的可行方案。

Formation and Degradation of Lunar Crater Ray and Possible Geochronology Application

Crater rays are formed during a cratering event as target material is ballistically ejected to distances of many crater radii forming narrow, generally high albedo, approximately linear features extending outward from the crater. The formation and degradation of lunar crater ray is one of the hot topics in lunar science. In this paper, the current understanding of crater ray origin, their different types on lunar surface, and the processes related with degradation of lunar crater ray systems are summarized. After the formation of the crater rays, the fresh and bright ejecta materials around the crater gradually mature under the joint action of a variety of geological processes, and reflectivity gradually disappears in accordance with the background. The OMAT profiles of young craters with various ages were compared. It is found that the average OMAT profile of crater ray could be fitted with the power law function; and that the shape of the OMAT profiles is strongly dependent on the exposure time on lunar surface as well as the crater age. This suggests that by using young crater with ray and known age as the reference, an empirical equation between the shape parameter and age could be built. This study provides a new method for dating young lunar craters.