Abstraact: Clinopyroxenes with excess Si have been described in run products from high-pressure experiments and inferred to have existed in nature from retrograde transformation phases. Here, we present the discovery of albitic jadeite, (Na,Ca,□1/4)(Al,Si)Si2O6 - the first natural, sodic clinopyroxene with excess Si occupying the octahedral cation site, M1, and a corresponding ¼ vacancy on the M2-site in the Ries impact structure and in a suite of L6 ordinary chondrites, EET 13014, EET 13052, NWA 1662, and TIL 08001. Garnet compositions in these samples indicate shock pressures of 18-22 GPa. Based on our survey, albitic jadeite is likely to be rather common in terrestrial and meteoritic shock-metamorphic environments. Shock-generated jadeite should be reexamined with respect to excess Si.
|Number of pages||6|
|Publication status||Published - 2022 Apr 1|
Bibliographical noteFunding Information:
We thank V. Stähle and M. Trieloff for providing material of the Ries xenolith thin section ZLN100 for this study, Chang-kun Park of Korea Polar Research Institute for providing TIL 08001, and D. Stöffler for stimulating discussions. SEM, EDS, EBSD, and EPMA analyzes were carried out at the Caltech GPS Division Analytical Facility, which is supported, in part, by NSF Grants EAR-0318518 and DMR-0080065. O.T. acknowledges support by NSF EAR-1838330. Y.L. thanks the supports by the Leader Researcher program (NRF-2018R1A3B1052042) of the Korean Ministry of Science, ICT and Planning and PE20200 funded by the Korea Polar Research Institute. GSECARS is supported through DOE Award DESC0005278, and NSF award EAR-1128799-0318518, DE-FG02-94ER14466, and DMR-0080065. The Advanced Photon Source, a DOE Office of Science User Facility, is operated by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
© 2022 Mineralogical Society of America.
All Science Journal Classification (ASJC) codes
- Geochemistry and Petrology