Data for: Quantitative Evaluation of Shock Metamorphism in Clinopyroxene Using in situ X-ray Diffraction Measurement of Lattice Strain
Description
X-ray diffraction (XRD) patterns for the study “Quantitative Evaluation of Shock Metamorphism in Clinopyroxene Using in situ X-ray Diffraction Measurement of Lattice Strain.” XRD patterns were collected from select targets in three Martian meteorites (Allan Hills (ALHA) 77005, Nakhla, and Zagami), as well as from three sets of experimentally shocked terrestrial clinopyroxene (cpx) samples (A0, A1, A2, B0, B3, and HEXP6). A0 and B0 are both unshocked, with A0 being a monomineralic cpx sample and B0 being a gabbro from the Bushveld Igneous Complex (BIC). A1 and A2 are monomineralic cpx samples that were shocked at 8 GPa and 22 GPa, respectively, with a light gas gun at the University of Kent. B3 is BIC gabbro from the shocked to 50 GPa by a flat plate accelerator (FPA) for another study (Meyer et al. 2011. Meteoritics & Planetary Sciences, 46: 701-718). HEXP6 is monomineralic diopside shocked to 20 GPa by FPA at the Experimental Impact Laboratory at the National Aeronautics and Space Administration Johnson Space Centre. XRD patterns for all samples were collected using an in situ micro X-ray diffractometer equipped with a Co kα source and an area detector from targets on intact unpowdered samples. Data was collected using General Area Detector Diffraction System (GADDS) software. They are not powder patterns. For more information regarding in situ micro XRD please see Flemming (2007. Canadian Journal of Earth Sciences, 44: 1333-1346). Data for each target is presented in four files: two .gfrm files, one .tif file, and one .raw file. The .gfrm files are two overlapping frames of 2-D XRD patterns that can be processed with the relevant software (e.g., GADDS, DIFFRACplus.EVA). The .tif file is a visual representation of the .gfrm frames. The .raw file is an integration of both .gfrm files into a traditional intensity versus 2θ plot and can be processed with the relevant software (e.g., DIFFRACplus.EVA). The .raw files can be used for mineral identification, while the .gfrm files can be used to isolate individual XRD peaks for peak width measurements. This work measured peak widths in 2θ for single peaks that matched exclusively cpx. Peak widths were measured as integral breadth. Lists of peaks measured in 2θ for each target for the study is in the attached guide.
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Steps to reproduce
Clinopyroxene samples experimentally shocked to varying peak shock pressures were acquired. These samples were both monomineralic and polymineralic, with polymineralic samples originating from a peridodite and a gabbro. These samples were shocked to known peak shock pressures at three different laboratories, with one laboratory using a light gas gun and two using flat plate accelerators. Please see dataset description and attached guide for the peak shock pressures experienced by each sample. Clinopyroxene-bearing martian meteorites were also acquired. Please see dataset description and attached guide for details regarding these meteorites. XRD patterns for targetted areas all samples were collected using an in situ micro X-ray diffractometer equipped with a Co kα source and an area detector from targets on intact unpowdered samples. Data was collected using General Area Detector Diffraction System (GADDS) software. They are not powder patterns. For more information regarding in situ micro XRD please see Flemming (2007. Canadian Journal of Earth Sciences, 44: 1333-1346). GADDS images were further processed using the DIFFRACplus.EVA, where full GADDS images were integrated into 1D intensity versus 2θ plots were made as .raw files. These .raw files were initially matched to minerals in the International Centre for Diffraction Data (ICDD) database. Single peaks that were unique to clinopyroxene were identified. Once unique clinopyroxene peaks were identified, the original GADDS images were further processed to integrate each individual peak into discontinuous 1D intensity versus 2θ plots (.raw files) to ensure no peak overlap occurred and that only complete peaks were used. Due to issues with file conversions of discontinuous patterns, these particular .raw files are not provided in this dataset, however they can be reproduced with the data provided. Please contact the authors if you desire access to these discontinuous patterns. Discontinuous patterns were then processed in DIFFRACplus.EVA. The integral breadth of each peak was measured using the create area tool.