Effect of FeO content to retention time of crater ray materials
Abstract
Ejecta blanket surrounding fresh crater shows bright ray because of the immature ejecta shortly after the impact cratering. Lunar crater rays disappear over time, and it's suggested that these are the reason why space weathering, micro-meteorite bombardments, and impact gardening process. Wilhelms described that the presence of crater rays is considered as the marker to define the Copernican - Eratosthenian boundary, and the immature rays, which had been formed by impact cratering in the Copernican, disappear within about 1.1 Gyr. So, it is important to estimate the crater rays retention time for the well-understanding of lunar geologic history. The purpose of this research is to investigate crater ray retention time of lunar craters using high-resolution data from Multiband Imager (MI) and Terrain Camera (TC) onboard Kaguya. We focus on space-weathering depending on the FeO content of lunar surface which differ in lunar highland and mare. We examined the retention time of crater ray materials on a part of farside and Mare Humorum. The size-frequency distributions of the detected craters with bright ray in highland and Mare Humorum correspond to isochrones for 250 Ma, 3 Ga, respectively. This result means that the retention time of crater ray materials on mare with high FeO contents is 250 Myr, which is lower than that of previous researches. Thus, the retention time of crater ray materials depends on the FeO content.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.P53A2049H
- Keywords:
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- 5470 PLANETARY SCIENCES: SOLID SURFACE PLANETS / Surface materials and properties;
- 6250 PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS / Moon