^1,2,3Lixin Gu,^1,3Sen Hu,^4,5Mahesh Anand,^1,2,3Xu Tang,^1,3,6Jianglong Ji,⁷Bin Zhang,^1,3,6Nian Wang,^1,3,6Yangting Lin
American Mineralogist 107, 1018-1029 Link to Article [http://www.minsocam.org/MSA/AmMin/TOC/2022/Abstracts/AM107P1018.pdf]
¹Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
²Electron Microscopy Laboratory, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
³Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 10029, China
⁴School of Physics Sciences, The Open University, Kents Hill, Milton Keynes MK7 6AA, U.K.
⁵Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, U.K.
⁶University of Chinese Academy of Sciences, Beijing 100049, China
⁷Analytical and Testing Center of Chongqing University, Chongqing 400044, China
Copyright: The Mineralogical Society of America

We report on the discovery of two high-pressure minerals, tuite and ahrensite, located in two
small shock-induced melt pockets (SIMP 1 and 2) in the Zagami martian meteorite, coexisting with
granular and acicular stishovite and seifertite. Tuite identified in this study has two formation pathways: decomposition of apatite and transformation of merrillite under high-P-T conditions. Chlorinebearing products, presumably derived from the decomposition of apatite, are concentrated along the
grain boundaries of tuite grains. Nanocrystalline ahrensite in the pyroxene clast in SIMP 2 is likely
to be a decomposition product of pigeonite under high-P-T conditions by a solid-state transformation
mechanism. The pressure and temperature conditions estimated from the high-pressure minerals in
the shock-induced melt pockets are ~12–22 GPa and ~1100–1500 °C, respectively, although previous
estimates of peak shock pressure are higher. This discrepancy probably represents the shift of kinetic
relative to thermodynamic phase boundaries, in particular the comparatively small region that we
examine here, rather than a principal disagreement between the peak shock conditions.