Cathodoluminescence of high‐pressure feldspar minerals as a shock barometer

1,2Masahiro Kayama,3,4Toshimori Sekine,5Naotaka Tomioka,6Hirotsugu Nishido,3Yukako Kato,6Kiyotaka Ninagawa,7Takamichi Kobayashi,8,9Akira Yamaguchi
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13092]
1Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai, Japan
2Creative Interdisciplinary Research Division, Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, Japan
3Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, Higashi‐Hiroshima, Japan
4Center for High Pressure Science and Technology Advanced Research, , Shanghai, China
5Kochi Institute for Core Sample Research, Japan Agency for Marine‐Earth Science and Technology, , Nankoku City, Kochi, Japan
6Department of Biosphere‐Geosphere Science, Okayama University of Science, , Okayama, Japan
7National Institute for Materials Science, , Tsukuba, Ibaraki, Japan
8National Institute of Polar Research, Tachikawa, Tokyo, Japan
9Department of Polar Science, School of Multidisciplinary Science, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Tokyo, Japan
Published by arrangement with John Wiley & Sons

Cathodoluminescence (CL) analyses were carried out on maskelynite and lingunite in L6 chondrites of Tenham and Yamato‐790729. Under CL microscopy, bright blue emission was observed in Na‐lingunite in the shock veins. Dull blue‐emitting maskelynite is adjacent to the shock veins, and aqua blue luminescent plagioclase lies farther away. CL spectroscopy of the Na‐lingunite showed emission bands centered at ~330, 360–380, and ~590 nm. CL spectra of maskelynite consisted of emission bands at ~330 and ~380 nm. Only an emission band at 420 nm was recognized in crystalline plagioclase. Deconvolution of CL spectra from maskelynite successfully separated the UV–blue emission bands into Gaussian components at 3.88, 3.26, and 2.95 eV. For comparison, we prepared K‐lingunite and experimentally shock‐recovered feldspars at the known shock pressures of 11.1–41.2 GPa to measure CL spectra. Synthetic K‐lingunite has similar UV–blue and characteristic yellow bands at ~550, ~660, ~720, ~750, and ~770 nm. The UV–blue emissions of shock‐recovered feldspars and the diaplectic feldspar glasses show a good correlation between intensity and shock pressure after deconvolution. They may be assigned to pressure‐induced defects in Si and Al octahedra and tetrahedra. The components at 3.88 and 3.26 eV were detectable in the lingunite, both of which may be caused by the defects in Si and Al octahedra, the same as maskelynite. CL of maskelynite and lingunite may be applicable to estimate shock pressure for feldspar‐bearing meteorites, impactites, and samples returned by spacecraft mission, although we need to develop more as a reliable shock barometer.

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