2:30 PM - 2:45 PM
[PPS06-14] Origin of geologic unit on the central peak of Jackson Crater
In craters on the lunar surface with diameters of 30 km or more, topographic features are formed by the uplift of subsurface materials. This topography is called the central peak, and analysis of the geological units distributed there provides information about the crustal composition of the Moon. However, it is reported that a part of central peak is covered by impact melt which is originated in the shallow crust. It is crucial to understand the crustal structure of the Moon by investigating whether the material distributed in the Central Peak is of shallow or deep origin.
In this study, we focus on examining the geological features of the central peak using multiple remote sensing data to identify whether the distributed materials are impact melts or crustal materials. We used the data from the Multiband Imager (MI) on the lunar orbiter KAGUYA (SELENE: Selenological and Engineering Explorer), the Terrain Camera (TC) and Diviner (Diviner Lunar Radiometer Experiment), and the Narrow Angle Cameras (NAC) on the Lunar Reconnaissance Orbiter (LRO), to study the central peak of Jackson Crater. Jackson Crater is one of the youngest craters in the moon and has been little affected by fragmentation, mixing, or space weathering from celestial impacts, making it easy to analyze its geology.
Three remote sensing analysis methods were used in this study. The first one is a geological analysis using multi-spectral data obtained from MI, we interpret the mineral distribution qualitatively by using continuum removal method. Then, we quantified the differences in iron content by Lucey method. The second one is outcrop survey focusing on the topographic characteristic of the central peak, using topographical data and high-resolution imagery. Digital terrain model (DTM) from TC and the images from NAC were used to observe the geomorphology on the central peak. In addition, the stratigraphic relationship can be confirmed if a crater is found where the lower lithology is exposed through the upper part of the central peak. Third one is a thermal inertia analysis using thermal infrared data. In this study, we used bolometric temperature data obtained from Diviner. The temperature difference between day and night was calculated to visualize the difference in thermal inertia of the surface materials. By combining these analytical methods, we analyzed the geology on Jackson Crater’s central peak.
According to the result of our spectral data analysis, the central peak of Jackson Crater is composed of materials with high albedo at the periphery and low albedo at the central part in the 750 nm wavelength band. We verified the high albedo material as felsic and the low albedo material as mafic. By Lucey method, the mafic central part has a high Fe content, while the felsic peripheral part has a Fe content close to zero. From the results of outcrop survey by combining DTM and high-resolution images with iron content data, A boundary region of mafic material and felsic material was identified where mafic material was orthogonal to the contour line from the higher central area to the lower peripheral area. The presence of this region shows that the mafic material flowed over the felsic material. In the central part, there is a area where felsic material appears to be exposed and the layer composed of mafic material appears to be thin in thickness. We identified 3036 craters distributed in layers of mafic material, of which, 148 craters were identified where the felsic material appears to be exposed through the mafic material. However, no craters with diameters large enough to allow our multispectral data to confirm the felsic material were found. The result of thermal inertia analysis by Diviner shows that the thermal inertia of the mafic central part is less than 100, while the thermal inertia of some of the felsic peripheral area is from 100 to 200 which is slightly higher.
In conclusion the central peak of Jackson Crater is divided into a mafic region and felsic region. We found that the mafic region has a thin layer and was deposited as if it flowed over the felsic region. In other words, the mafic material is of shallow crustal origin, formed and deposited by impact, rather than deep uplift material. The estimated thermal inertia of the materials is also consistent with the interpretation that the mafic material is more brittle than the felsic material which is basement of deep crustal origin.
In this study, we focus on examining the geological features of the central peak using multiple remote sensing data to identify whether the distributed materials are impact melts or crustal materials. We used the data from the Multiband Imager (MI) on the lunar orbiter KAGUYA (SELENE: Selenological and Engineering Explorer), the Terrain Camera (TC) and Diviner (Diviner Lunar Radiometer Experiment), and the Narrow Angle Cameras (NAC) on the Lunar Reconnaissance Orbiter (LRO), to study the central peak of Jackson Crater. Jackson Crater is one of the youngest craters in the moon and has been little affected by fragmentation, mixing, or space weathering from celestial impacts, making it easy to analyze its geology.
Three remote sensing analysis methods were used in this study. The first one is a geological analysis using multi-spectral data obtained from MI, we interpret the mineral distribution qualitatively by using continuum removal method. Then, we quantified the differences in iron content by Lucey method. The second one is outcrop survey focusing on the topographic characteristic of the central peak, using topographical data and high-resolution imagery. Digital terrain model (DTM) from TC and the images from NAC were used to observe the geomorphology on the central peak. In addition, the stratigraphic relationship can be confirmed if a crater is found where the lower lithology is exposed through the upper part of the central peak. Third one is a thermal inertia analysis using thermal infrared data. In this study, we used bolometric temperature data obtained from Diviner. The temperature difference between day and night was calculated to visualize the difference in thermal inertia of the surface materials. By combining these analytical methods, we analyzed the geology on Jackson Crater’s central peak.
According to the result of our spectral data analysis, the central peak of Jackson Crater is composed of materials with high albedo at the periphery and low albedo at the central part in the 750 nm wavelength band. We verified the high albedo material as felsic and the low albedo material as mafic. By Lucey method, the mafic central part has a high Fe content, while the felsic peripheral part has a Fe content close to zero. From the results of outcrop survey by combining DTM and high-resolution images with iron content data, A boundary region of mafic material and felsic material was identified where mafic material was orthogonal to the contour line from the higher central area to the lower peripheral area. The presence of this region shows that the mafic material flowed over the felsic material. In the central part, there is a area where felsic material appears to be exposed and the layer composed of mafic material appears to be thin in thickness. We identified 3036 craters distributed in layers of mafic material, of which, 148 craters were identified where the felsic material appears to be exposed through the mafic material. However, no craters with diameters large enough to allow our multispectral data to confirm the felsic material were found. The result of thermal inertia analysis by Diviner shows that the thermal inertia of the mafic central part is less than 100, while the thermal inertia of some of the felsic peripheral area is from 100 to 200 which is slightly higher.
In conclusion the central peak of Jackson Crater is divided into a mafic region and felsic region. We found that the mafic region has a thin layer and was deposited as if it flowed over the felsic region. In other words, the mafic material is of shallow crustal origin, formed and deposited by impact, rather than deep uplift material. The estimated thermal inertia of the materials is also consistent with the interpretation that the mafic material is more brittle than the felsic material which is basement of deep crustal origin.