Formation of a metastable hollandite phase from amorphous plagioclase: A possible origin of lingunite in shocked chondritic meteorites

Tomoaki Kubo, Mari Kono, Masahiro Imamura, Takumi Kato, Seiichiro Uehara, Tadashi Kondo, Yuji Higo, Yoshinori Tange, Takumi Kikegawa

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We conducted high-pressure experiments in plagioclase with different anorthite contents at 18–27 GPa and 25–1750 °C using both a laser-heated diamond anvil cell and a Kawai-type multi-anvil apparatus to clarify the formation conditions of the hollandite phase in shocked chondritic and Martian meteorites. Lingunite (NaAlSi3O8-rich hollandite) was found first to crystallize from amorphous oligoclase as a metastable phase before decomposing into the final stable state. This process might account for the origin of lingunite found along with maskelynite in shocked chondritic meteorites. Metastable lingunite appeared at ∼20–24 GPa and ∼1100–1300 °C in laboratory tests lasting tens of minutes; however, it might also form at the higher temperatures and shorter time periods of shock events. In contrast, the hollandite phase was not observed during any stage of crystallization when using albite or labradorite as starting materials. The formation process of (Ca,Na)-hollandite in the labradorite composition found in Martian shergottites remains unresolved. The orthoclase contents of the hollandite phase both in shocked meteorites (2.4–8.2 mol%) and our oligoclase sample (3.9 mol%) are relatively high compared to the albite and labradorite samples (0.6 and 1.9 mol%, respectively). This might critically affect the crystallization kinetics of hollandite phase.

Original languageEnglish
Pages (from-to)50-57
Number of pages8
JournalPhysics of the Earth and Planetary Interiors
Volume272
DOIs
Publication statusPublished - Nov 2017

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Geophysics
  • Physics and Astronomy (miscellaneous)
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'Formation of a metastable hollandite phase from amorphous plagioclase: A possible origin of lingunite in shocked chondritic meteorites'. Together they form a unique fingerprint.

  • Cite this