title: Luminescence Spectroscopical Properties of Plagioclase Particles from the Hayabusa Sample Return Mission: An Implication for Study of Space Weathering Processes in the Asteroid Itokawa.
abstract: We report a systematic spectroscopical investigation of three plagioclase particles (RB-QD04-0022, RA-QD02-0025-01, and RA-QD02-0025-02) returned by the Hayabusa spacecraft from the asteroid Itokawa, by means of scanning electron microscopy, cathodoluminescence microscopy/spectroscopy, and micro-Raman spectroscopy. The cathodoluminescence properties are used to evaluate the crystallization effects and the degree of space weathering processes, especially the shock-wave history of Itokawa. They provide new insights regarding spectral changes of asteroidal bodies due to space weathering processes. The cathodoluminescence spectra of the plagioclase particles from Itokawa show a defect-related broad band centered at around 450 nm, with a shoulder peak at 425 nm in the blue region, but there are no Mn- or Fe-related emission peaks. The absence of these crystal field-related activators indicates that the plagioclase was formed during thermal metamorphism at subsolidus temperature and extreme low oxygen fugacity. Luminescence characteristics of the selected samples do not show any signatures of the shock-induced microstructures or amorphization, indicating that these plagioclase samples suffered no (or low-shock pressure regime) shock metamorphism. Cathodoluminescence can play a key role as a powerful tool to determine mineralogy of fine-grained astromaterials.
authors.affiliation: 1Department of Geology,University of Johannesburg,Johannesburg,2600 Auckland Park,South Africa.
authors.forename: Arnold
authors.initials: A
authors.lastname: Gucsik
authors.affiliation: 3Department of Earth and Planetary Materials Science,Graduate School of Science,Tohoku University,Sendai 980-8578,Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: 4Laboratory Astrophysics and Cluster Physics Group at the Institute of Solid State Physics Friedrich Schiller University Jena,Helmholtzweg 3, D-07745 Jena,Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Jäger
authors.affiliation: 5Department of Applied Physics,Okayama University of Science,1-1 Ridai-cho,Kita-ku,Okayama, 700-0005,Japan.
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Ninagawa
authors.affiliation: 6Department of Biosphere-Geosphere System Science,Okayama University of Science,1-1 Ridai-cho,Okayama, 700-0005,Japan.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Nishido
authors.affiliation: 7Department of Earth and Planetary Material Sciences, Faculty of Science,Tohoku University Creative Interdisciplinary Research Division,Frontier Research Institute for Interdisciplinary Sciences,Tohoku University,Aramaki aza Aoba 6-3,Aoba-ku,Sendai 980-8578,Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kayama
authors.affiliation: 8Division of Earth and Planetary Sciences, Faculty of Science,Graduate School of Science,Kyoto University,Kitashirakawaoiwake-cho,Sakyu-ku,Kyoto-shi 606-8502,Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Tsuchiyama
authors.affiliation: 9Savaria University Center,University of West Hungary,Karolyi Gaspar ter 4,Szombathely, H-9700,Hungary.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ott
authors.affiliation: 10Astronomical Research Institute,Hungarian Academy of Sciences,Konkoly-Thege M. út 29-33,1121,Budapest,Hungary.
authors.forename: Ákos
authors.initials: Á
authors.lastname: Kereszturi
keywords: asteroid; cathodoluminescence; micro-Raman spectroscopy; mineralogy; space weathering