WIP: A Web-based program for indexing planar features in quartz grains and its usage.

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Losiak, A., Golebiowska, I., Ferrière, L., Wojciechowski, J., Huber, M. S. and Koeberl, C.

Meteoritics & Planetary Science
Article first published online: 4 MAR 2016
DOI: 10.1111/maps.12614

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“Planar deformation features (PDFs) in quartz are the most important diagnostic features that allow the unambiguous identification of impact structures on Earth. In order to confirm that these features (that are characterized by planar character and form along specific crystallographic planes) are indeed PDFs, they need to be properly investigated and indexed. Following universal-stage measurements, the process of indexing is usually performed manually, using a Wulff stereonet and following a strict procedure, which is time consuming and error prone. In this article, we present WIP, a new Web-based program for indexing planar deformation features in quartz. The correctness of our program is shown by its application to measurements that had previously been indexed manually. The observed minor differences, especially in the absolute frequency percentage of PDFs, are negligible and not significant enough to influence the estimation of shock pressure that could be calculated from the indexed results. Usability of this program is shown using the spatial relationships between a statistically significant number of 278 quartz grains with 409 sets of PDFs analyzed within the area (~35 mm2) of a single thin section of a meta-greywacke from the Bosumtwi impact structure. Our program is not only more accurate and faster than the manual (graphical) method but also removes the human error from the plotting process and allows control of several parameters, such as the value of estimated measurement error used in the indexing calculation or method of aggregated error handling. The program also provides information about the angles between the planes of the measured PDF sets present in a grain, which allows determination of the angles between (for example) indexed {inline image} and {inline image} sets.”

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