09:30 〜 09:45
[PPS08-03] Estimated origin of olivine bearing rocks observed at the SLIM landing site on the Moon
キーワード：小型月着陸実証機、マルチバンド分光カメラ、月マントル、カンラン石
Previous remote-sensing data obtained by the SELENE (Kaguya) Spectral Profiler (SP) found exposures with olivine-rich spectral features, globally distributed on the lunar surface [1]. Their distributions surrounding large basins, their spectral characteristics indicating olivine-rich composition suggest that these olivine-rich exposures possibly originated from the mantle that is excavated from depth by basin-forming impacts [1]. However, it has been debated if the identified olivine originated from the lunar mantle or not.
One olivine-rich exposure identified by SELENE (Kaguya) Multiband Imager (MI) (a fresh crater Shioli having 270 m diameter), situated outside the southern rim of Theophilus (11.4°S, 26.4°E) was selected as the landing site for Japanese lunar explorer, Smart Lander for Investigating Moon (SLIM) mission. In this study, we are going to investigate if the identified olivine at the SLIM landing site originated from the lunar mantle or not based on both remote sensing observation and landing in-situ spectral observation. We used remote sensing data obtained by the MI [2] (has 9 band from visible to near-infrared wavelength) and the Multi-Band Camera (MBC) [3] on the SLIM lander for geological and spectral analyses. The MBC has a telescopic optical system capable of near-infrared high-spatial-resolution observation in 10 bands. The band assignments are 750, 920, 950, 970, 1,000, 1,050, 1,100, 1,250, 1,550, and 1,650 nm, and its spatial resolution is 1.1 mm/pixel at 10 m for mineralogical-scale observation.
Based on the spectra obtained a by the MBC, we found that a rock we labeled as “Dalmatian” contained large olivine clasts up to 3 - 4 cm in diameter and a mixture of olivine and low-Ca pyroxene unit. No plagioclase grains are identified in the olivine clasts, while the olivine and low-Ca pyroxene unit contains very limited amount of plagioclase grains. The lack of plagioclase and the large size of the olivine clast in Dalmatian indicate that the origin of this unit is plutonic. Based on the observed rock texture, significantly mafic-rich mineralogy, Mg# (based on the apparently shorter absorption center wavelength around 1050 nm) consistent to the lunar mantle, and geologic setting, we interpret that the olivine clasts in Dalmatian originated from the same olivine-rich lithology observed by the MI at the central peak, indicating mantle origin.
[1] Yamamoto et al. (2010), Nature GeoSci. 3, 533-536. [2] Ohtake et al. (2009) Nature, 461, 236-241. [3] Saiki et al. (2024), 55th LPSC, abstract#1801.
One olivine-rich exposure identified by SELENE (Kaguya) Multiband Imager (MI) (a fresh crater Shioli having 270 m diameter), situated outside the southern rim of Theophilus (11.4°S, 26.4°E) was selected as the landing site for Japanese lunar explorer, Smart Lander for Investigating Moon (SLIM) mission. In this study, we are going to investigate if the identified olivine at the SLIM landing site originated from the lunar mantle or not based on both remote sensing observation and landing in-situ spectral observation. We used remote sensing data obtained by the MI [2] (has 9 band from visible to near-infrared wavelength) and the Multi-Band Camera (MBC) [3] on the SLIM lander for geological and spectral analyses. The MBC has a telescopic optical system capable of near-infrared high-spatial-resolution observation in 10 bands. The band assignments are 750, 920, 950, 970, 1,000, 1,050, 1,100, 1,250, 1,550, and 1,650 nm, and its spatial resolution is 1.1 mm/pixel at 10 m for mineralogical-scale observation.
Based on the spectra obtained a by the MBC, we found that a rock we labeled as “Dalmatian” contained large olivine clasts up to 3 - 4 cm in diameter and a mixture of olivine and low-Ca pyroxene unit. No plagioclase grains are identified in the olivine clasts, while the olivine and low-Ca pyroxene unit contains very limited amount of plagioclase grains. The lack of plagioclase and the large size of the olivine clast in Dalmatian indicate that the origin of this unit is plutonic. Based on the observed rock texture, significantly mafic-rich mineralogy, Mg# (based on the apparently shorter absorption center wavelength around 1050 nm) consistent to the lunar mantle, and geologic setting, we interpret that the olivine clasts in Dalmatian originated from the same olivine-rich lithology observed by the MI at the central peak, indicating mantle origin.
[1] Yamamoto et al. (2010), Nature GeoSci. 3, 533-536. [2] Ohtake et al. (2009) Nature, 461, 236-241. [3] Saiki et al. (2024), 55th LPSC, abstract#1801.