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Cathodoluminescence spectral study of alkali feldspar and plagioclase in Yamato Martian nakhlite meteorites M. Kayama 1, A. Gucsik 2, N. Matsuda 3, H.

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Presentation on theme: "Cathodoluminescence spectral study of alkali feldspar and plagioclase in Yamato Martian nakhlite meteorites M. Kayama 1, A. Gucsik 2, N. Matsuda 3, H."— Presentation transcript:

1 Cathodoluminescence spectral study of alkali feldspar and plagioclase in Yamato Martian nakhlite meteorites M. Kayama 1, A. Gucsik 2, N. Matsuda 3, H. Nishido 1 and K. Ninagawa 4 1 Okayama Unversity of Science, RINS, Okayama, Japan 2 Max Planck Institute for Chemistry, Mainz, Germany 3 Okayama Unversity of Science, ISEI, Tottori, Japan 4 Okayama Unversity of Science, Dept. of Applied Physics, Okayama, Japan NIPR, Tokyo, 07 June 2007

2 Introduction 1. Detection and Observation of structural defects and impurity trace elements 2. Suggestion about crystal fields responsible for a structural configuration, which is altered by shock metamorphism evaluation of shock event in Y CL measurement allows CL characterization of feldspar minerals in Y and

3 Cathodoluminescence (CL) electron irradiation Micrograph of alkali feldspar 1 mm CL image of alkali feldspar

4 Götze, 1998

5

6 CL spectral measurements were performed on natural and experimentally shocked oligoclases (An19.7 single crystal shocked between 10.5 GPa and 45 GPa) and plagioclases from the equilibrated ordinary chondrites (Dar al Gani, Tenham) (Kaus and Bischoff, 2000).

7 In a pioneering study, Sippel and Spencer (1970) observed that the shock metamorphism caused peak shifts from green peak toward the red peak, peak broadening and decrease of luminescence intensity than in the undamaged counterpart in the CL spectra of shock-metamorphosed lunar feldspars. They noted that the distortions or disorder in the crystal field results in crystal field perturbations and these local variations occur broadened distribution of excited state energies due to shock metamorphism. Terrestrial plagioclase (An 85 ) Plagioclase from lunar crystalline rocks Plagioclase from lunar breccia Maskelynite

8 Literature Review: [1] Götze et al., (2000) in: M. Pagel, V.Barbin, P. Blanc, D. Ohnenstetter (Eds.) Cathodoluminescence in Geosciences, Springer, ; [2] Petrov (1994) Amer. Miner. 79, ; [3] Marshall (1988), Unwin Hyman, Boston. 146 pp; [4] Hayward (1998), in: L.J. Cabri, D.J. Vaughan (Eds.) Modern Approaches to Ore and Environmental Mineralogy, Mineralogical Association of Canada Short Course Series, 27, pp ; [5] Götze et al., (1999) Amer. Miner. 84, ; [6] Sippel and Spencer (1970), Proc. Apollo 11 Lunar Sci.Conf. 3, ; [7] Ramseyer et al., (1992), Tectonophysics 216, ; [8] Kaus and Bischoff (2000), Meteoritics Planet. Sci. 35 A 86; [9] Boggs et al., (2001) Meteoritics Planet. Sci. 36,

9 #1 Measurement #2 Measurement

10 A schematic figure showing relationships between crystal field strength [Dq], distance of O-Mn [a], and CL emission [λ] as a function of the increasing shock pressure [P]

11 Meteorite Micrograph of Y CL image of Y Nakhlite Y (Sub. No. 1-5) minerals in mesostasis : alkali feldspar, plagioclase and silica minerals

12 Alkali feldspar and plagioclase Alkali feldspar (Or 80 ) Plagioclase (Ab 70 ) no transformation to maskelynite BSE image of alkali feldspar BSE image of plagioclase AF PL

13 Methods Luminoscope Photograph of Luminoscope 1 mm CL image of alkali feldspar Observation of CL color image Comparison with optical image

14 Methods Photograph of SEM-CLSchematic diagram of SEM-CL SEM-CL Measurement of CL spectra Observation of CL image with SEM and BSE image Accelerating voltage: 15 kV Beam current: 1.0 nA

15 CL images of alkali feldspar and plagioclase BC A Figure (A) CL color images of mesostasis (B) CL image of alkali feldspar (C) CL image of plagioclase AF PL

16 CL spectra of alkali feldspar Peak position Blue spectral peak Terrestrial Y nm 420 nm Red spectral peak Terrestrial Y nm 755 nm

17 CL spectra of plagioclase

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19 Peak position Yellow spectral peak Terrestrial Y nm 575 nm Red spectral peak Terrestrial Y nm 780 nm CL spectra of plagioclase

20 Conclusion CL emission peak of alkali feldspar and plagioclase in Y differ from that of terrestrial analogues. UV spectral peak are not observed in CL spectra of plagioclase in Y CL spectra of plagioclase in Y show slight peak shift by comparing with experimentally shocked plagioclase at 20 GPa Impact pressure shocked on nakhlite is relatively low

21 Thank you very much for your attention


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