Partial amorphization of experimentally shocked plagioclase: A spectroscopic study

Author(s)
Lidia Pittarello, J. Fritz, Julia Roszjar, Christoph Lenz, Chutimun Chanmuang Nasdala, Christian Koeberl
Abstract

Shock amorphization of plagioclase, from partial to complete, has been used to evaluate the degree of shock in meteorites. Important information on the shock amplitude can be derived from the measurement of the refractive index in plagioclase, either from mineral separates or in petrographic thin sections. However, this technique is time-consuming, and associated sample preparations are considered destructive and are not always possible for precious and rare meteorite samples. In addition, plagioclase amorphization is commonly inhomogeneous at the sample scale and a statistically meaningful number of grains must be considered. Here, we apply several nondestructive spectroscopic techniques, such as Raman spectroscopy, photoluminescence, and cathodoluminescence, to plagioclase experimentally shocked at 28 GPa, and thus in the transition regime between crystalline plagioclase and fully amorphous material. Most of the plagioclase was transformed into diaplectic glass at 28 GPa, yet some grains exhibit heterogeneously distributed crystalline domains. This confirms that intrinsic and extrinsic factors lead to local variations in the intensity of the shock pressure within individual plagioclase crystals of homogeneous composition. The amorphization of plagioclase can qualitatively (and potentially also quantitatively) be investigated by spectroscopic techniques, highlighting such local variations in the shock efficiency.

Organisation(s)
Department of Lithospheric Research, Department of Mineralogy and Crystallography
External organisation(s)
Naturhistorisches Museum Wien (NHM), Ghent University
Journal
Meteoritics and Planetary Science
Volume
55
Pages
669-678
No. of pages
10
ISSN
1086-9379
DOI
https://doi.org/10.1111/maps.13445
Publication date
03-2020
Peer reviewed
Yes
Austrian Fields of Science 2012
105105 Geochemistry
Keywords
ASJC Scopus subject areas
Geophysics, Space and Planetary Science
Portal url
https://ucris.univie.ac.at/portal/en/publications/partial-amorphization-of-experimentally-shocked-plagioclase-a-spectroscopic-study(d4cb85c7-f1fc-4c72-8eab-b111d1f09ca8).html