Publication Details

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Title: Variable microstructural response of baddeleyite to shock metamorphism in young basaltic shergottite NWA 5298 and improved U‐Pb dating of Solar System events
Authors: J. R. Darling, D. E. Moser, I. R. Barker, K. T. Tait, K. R. Chamberlain, A. K. Schmitt, and B. C. Hyde
Publication: Earth Planet. Sci. Lett., v. 444, p. 1‐12.
Publish Date: 2016
DOI: 10.1016/j.epsl.2016.03.032
PDF: pdf
BibTEX Citation: Darling:2016.bib


The accurate dating of igneous and impact events is vital for the understanding of Solar System evolution, but has been hampered by limited knowledge of how shock metamorphism affects mineral and whole‐rock isotopic systems used for geochronology. Baddeleyite (monoclinic ZrO2) is a refractory mineral chronometer of great potential to date these processes due to its widespread occurrence in achondrites and robust U‐Pb isotopic systematics, but there is little understanding of shock‐effects on this phase. Here we present new nano‐structural measurements of baddeleyite grains in a thin‐section of the highly‐shocked basaltic shergottite Northwest Africa (NWA) 5298, using high‐resolution electron backscattered diffraction (EBSD) and scanning transmission electron microscopy (STEM) techniques, to investigate shock‐effects and their linkage with U‐Pb isotopic disturbance that has previously been documented by in‐situ U‐Pb isotopic analyses. The shock‐altered state of originally igneous baddeleyite grains is highly variable across the thin‐section and often within single grains. Analyzed grains range from those that preserve primary (magmatic) twinning and trace‐element zonation (baddeleyite shock Group 1), to quasi‐amorphous ZrO2