^1,2Annemarie E. Pickersgill, ¹Roberta L. Flemming,^1,3Gordon R. Osinski
¹Department of Earth Sciences and Centre for Planetary Science and Exploration, University of Western Ontario, London, Ontario, Canada
²Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada
³School of Geographical & Earth Sciences, University of Glasgow, Lilybank Gardens, Glasgow, UK

Studies of shock metamorphism of feldspar typically rely on qualitative petrographic observations, which, while providing invaluable information, can be difficult to interpret. Shocked feldspars, therefore, are now being studied in greater detail by various groups using a variety of modern techniques. We apply in situ micro-X-ray diffraction (μXRD) to shocked lunar and terrestrial plagioclase feldspar to contribute to the development of a quantitative scale of shock deformation for the feldspar group. Andesine and labradorite from the Mistastin Lake impact structure, Labrador, Canada, and anorthite from Earth’s Moon, returned during the Apollo program, were examined using optical petrography and assigned to subgroups of the optical shock level classification system of Stöffler (1971). Two-dimensional μXRD patterns from the same samples revealed increased peak broadening in the chi dimension (χ), due to strain-related mosaicity, with increased optical signs of deformation. Measurement of the full width at half maximum along χ (FWHMχ) of these peaks provides a quantitative way to measure strain-related mosaicity in plagioclase feldspar as a proxy for shock level.

Reference
Pickersgill AE, Flemming RL, Osinski GR (2015) Toward quantification of strain-related mosaicity in shocked lunar and terrestrial plagioclase by in situ micro-X-ray diffraction. Meteoritics & Planetary Science (in Press)
Link to Article [DOI: 10.1111/maps.12514]
Published by arrangement with John Wiley & Sons