1,2,3Laura E. Jenkins, 1,2Roberta L. Flemming, 1,2Sam Nicholson, 4Mark Burchell, 4Kathryn Harriss, 5,6Anne H. Peslier, 5Roy G. Christoffersen, 7,8Jörg Fritz, 9Cornelia Meyer
Journal of Geophysical Research: Planets, 131, e2026JE010049
Open Access Link to Article [DOI: 10.1029/2026JE010049]
1Department of Earth Sciences, Western University, London, ON, Canada
2Institute for Earth & Space Exploration, Western University, London, ON, Canada
3Now at: Diamond Light Source, Didcot, UK
4Centre for Astrophysics and Planetary Science, School of Engineering, Mathematics and Physics, University of Kent, Canterbury, UK
5Jacobs, NASA Johnson Space Center (JSC), Houston, TX, USA
6Department of Geological Sciences, New Mexico State University, Las Cruces, NM, USA
7Saalbau Weltraum Projekt, Heppenheim, Germany
8Zentrum für Rieskrater und Impaktforschung Nördlingen (ZERIN), Nördlingen, Germany
9Horizontereignis gUG, Berlin, Germany
Published by arrangement with John Wiley & Sons
Shock metamorphism is a ubiquitous process in our solar system. Shock pressure can be related to the lattice strain (ε) of individual minerals within a shocked sample. The lattice strain can be quantified within intact samples by in situ micro-X-ray diffraction (μXRD) using the Williamson-Hall method. The Williamson-Hall lattice strain (W-H ε) method has so far only been calibrated for olivine. This work extends the W-H ε method to high-Ca clinopyroxene. We obtained three sets of experimentally shocked clinopyroxene samples and calculated ε for each sample using μXRD. We created a calibration curve that relates ε to peak shock pressure experienced. Its trend line has the equation P = 222.85ε−8.60 GPa, with an error of ±9 GPa. The calibration curve was applied to the Martian meteorites Nakhla, Zagami, and Allan Hills A77005 (ALHA 77005) to compare these results with the meteorites’ optically determined shock stages. The peak shock pressures returned by the calibration curve are: 15 ± 9 GPa for Nakhla, 35 ± 9 GPa for Zagami, and 68 ± 9 GPa for ALHA 77005. These results agree with the meteorites’ previously determined shock stages. The development of a W-H ε calibration curve for high-Ca clinopyroxene is preliminary; however, it expands this method for evaluating shock metamorphism of shocked clinopyroxene-bearing samples, such as Martian shergottites.
