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Micro‐FTIR Spectroscopy of Lunar Pyroclastic and Impact Glasses as a New Diagnostic Tool to Discern Them
Author(s) -
Zeng Xiaojia,
Li Xiongyao,
Martin Dayl,
Tang Hong,
Yu Wen,
Liu Jianzhong,
Wang Shijie
Publication year - 2019
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1029/2019je006237
Subject(s) - pyroclastic rock , basalt , fourier transform infrared spectroscopy , lunar mare , breccia , geology , mineralogy , spectroscopy , volcanism , impact crater , lunar soil , volcano , analytical chemistry (journal) , materials science , geochemistry , astrobiology , chemistry , optics , physics , seismology , astronomy , chromatography , tectonics
Lunar glasses are characterized by complex origin (i.e., volcanism or impact), compositional diversity (e.g., picritic, basaltic, or feldspathic), and visible/near‐infrared spectra similarity. This makes it is problematic to distinguish different types of lunar glasses in laboratory and remote data. In this study, we present micro‐FTIR (Fourier Transform Infrared) spectroscopy spectra (550–1450 cm –1 ) of a suite of lunar volcanic origin glasses (i.e., pyroclastic glasses) and impact‐generated glasses (i.e., mare and highland impact glasses), identified in lunar breccia meteorite Northwest Africa 7948. The results show that lunar pyroclastic glasses, mare impact glasses, and highland impact glasses exhibit different FTIR spectral characteristics: (1) the Christiansen Feature positions of pyroclastic glasses are generally at a longer wavelength (i.e., >~8.3 μm equivalent to <~1,205 cm –1 ) than the spectra of mare and highland impact‐generated glasses (i.e., <~8.3 μm equivalent to >~1,205 cm –1 ); (2) a relatively strong minor peak was distinctly observed at longer wavelength (~13.5–16.5 μm equivalent to ~600–750 cm –1 ) for highland impact glasses. Therefore, new supplementary FTIR diagnostic criteria were proposed to discern different types of lunar glasses. Our studies demonstrated that midinfrared spectra could provide an effective tool to non‐destructively and quickly distinguish lunar glasses in laboratory (e.g., for the future Chang'E‐5 returned soils).