Pressure-induced amorphization in plagioclase feldspars: A time-resolved powder diffraction study during rapid compression

Autor: B. Rhymer, Zuzana Konôpková, Jesse S. Smith, Hanns-Peter Liermann, Lars Ehm, M. Sims, Eva-Regine Carl, N. Schrodt, Vivien Mohrholz, Timothy D. Glotch, Steven J. Jaret
Rok vydání: 2019
Předmět:
Zdroj: Earth and planetary science letters 507, 166-174 (2019). doi:10.1016/j.epsl.2018.11.038
ISSN: 0012-821X
DOI: 10.1016/j.epsl.2018.11.038
Popis: Earth and planetary science letters 507, 166 - 174 (2019). doi:10.1016/j.epsl.2018.11.038
The pressure-induced amorphization of the two endmembers of the plagioclase ((Na$_{1−x}$Cax)Al$_{1+x}$Si$_{3−x}$O$_8$) solid-solution, anorthite (CaAl$_2$Si$_2$O$_8$) and albite (NaAlSi$_3$O$_8$), has been studied as a function of compression rate by means of time-resolved powder diffraction. Anorthite and albite were compressed in a diamond anvil cell to 80 GPa at multiple rates from 0.05 GPa/s to 80 GPa/s. The amorphization pressure decreases with increasing compression rate. This negative strain rate sensitivity indicates a change in deformation mechanism in the plagioclase solid-solution endmembers from brittle to ductile with increasing compression rate. The presented data support the previously proposed shear deformation mechanism for the amorphization of plagioclase. Furthermore, amorphization progresses over a wide pressure range suggesting heterogeneous amorphization, similar to observations based on recovered material from shock-compression experiments of plagioclase. Our experiments support the contention that amorphization pressures for plagioclase may occur at lower pressures than usually considered.
Published by Elsevier, Amsterdam [u.a.]
Databáze: OpenAIRE
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