Cathodoluminescence spectral study of

alkali feldspar and plagioclase in Yamato

Martian nakhlite meteorites

M. Kayama1, A. Gucsik2, N. Matsuda3, H. Nishido1 and K. Ninagawa4

1Okayama Unversity of Science, RINS, Okayama, Japan

2Max Planck Institute for Chemistry, Mainz, Germany

3Okayama Unversity of Science, ISEI, Tottori, Japan

4Okayama Unversity of Science, Dept. of Applied Physics, Okayama, Japan

NIPR, Tokyo, 07 June 2007

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 Y000749

CL measurement allows

CL characterization of feldspar minerals in Y000749

and

Cathodoluminescence (CL)

electron irradiation

Micrograph of alkali feldspar

1 mm 1 mm

CL image of alkali feldspar

Götze, 1998

Götze, 1998

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).

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 (An85)

Plagioclase from lunar crystalline rocks

Plagioclase from lunar breccia

Maskelynite

Literature Review:

[1] Götze et al., (2000) in: M. Pagel, V.Barbin, P. Blanc, D. Ohnenstetter (Eds.) Cathodoluminescence in Geosciences, Springer, 245-270;

[2] Petrov (1994) Amer. Miner. 79, 221-239;

[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. 269-325;

[5] Götze et al., (1999) Amer. Miner. 84, 1027-1032;

[6] Sippel and Spencer (1970), Proc. Apollo 11 Lunar Sci.Conf. 3, 2413-2426;

[7] Ramseyer et al., (1992), Tectonophysics 216, 195-204;

[8] Kaus and Bischoff (2000), Meteoritics Planet. Sci. 35 A 86;

[9] Boggs et al., (2001) Meteoritics Planet. Sci. 36, 783-793.

#1 Measurement

#2 Measurement

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]

Meteorite

Micrograph of Y000749 CL image of Y000749

Nakhlite

Y000749 (Sub. No. 1-5)

minerals in mesostasis : alkali feldspar, plagioclase and silica minerals

Alkali feldspar and plagioclase

Alkali feldspar (Or80)

Plagioclase (Ab70)

no transformation to maskelynite

BSE image of alkali feldspar BSE image of plagioclase

AFPL

Methods

Luminoscope

Photograph of Luminoscope

1 mm

CL image of alkali feldspar

Observation of CL color image

Comparison with optical image

Methods

Photograph of SEM-CL Schematic 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

CL images of alkali feldspar and plagioclase

B C

AFigure

(A) CL color images

of mesostasis

(B) CL image of

alkali feldspar

(C) CL image of

plagioclase

AF

PL

CL spectra of alkali feldspar

CL spectra of alkali feldspar

Peak position

Blue spectral peak

Terrestrial Y000749

400 nm 　 420 nm

Red spectral peak

Terrestrial Y000749

710 nm 755 nm

CL spectra of plagioclase

CL spectra of plagioclase

CL spectra of plagioclase

CL spectra of plagioclase

CL spectra of plagioclase

Peak position

Yellow spectral peak

Terrestrial Y000749

560 nm 　 575 nm

Red spectral peak

Terrestrial Y000749

750 nm 780 nm

CL spectra of plagioclase

Conclusion

CL emission peak of alkali feldspar and plagioclase in Y000749 differ from t

hat of terrestrial analogues.

UV spectral peak are not observed in CL spectra of plagioclase in Y000749

CL spectra of plagioclase in Y000749 show slight peak shift by comparing

with experimentally shocked plagioclase at 20 GPa

Impact pressure shocked on nakhlite is

relatively low

Thank you very much for your attention