Systematic study of universal‐stage measurements of planar deformation features in shocked quartz: Implications for statistical significance and representation of results

By L. Ferrière, J. Morrow, T. Amgaa, C. Koeberl. 2009

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Abstract— The presence of shocked quartz is one of the key lines of evidence for the impact origin of rocks. Crystallographic orientations of planar deformation feature (PDF) sets in shocked quartz have been used to constrain the peak shock pressure that these grains have experienced. So far no systematic and comparative studies of the various orientation measurement methods and their biases are available. Therefore, three shocked‐quartz‐bearing thin sections from a meta‐greywacke clast in breccia, a biotite‐gneiss, and a sandstone, respectively, were independently analyzed by three operators (two experienced and one inexperienced) using a four‐axis universal‐stage (U‐stage), in order to evaluate the quality, precision, repeatability, and representativeness of U‐stage measurements. Based on the indexing of PDF sets using a new version of the commonly used stereographic projection template, the study of 1751 PDF set orientations in 666 quartz grains in three different shocked rocks shows that differences in abundance and orientation of various PDF sets, as measured by the three separate operators, are rather limited.

Subfields: Astronomy and Astrophysics, Atmospheric Science, Geophysics

View Paper: https://www.semanticscholar.org/paper/fc6c69e5d43c35fb3f9eaee025ad740197aae9cd