Correlating planar microstructures in shocked zircon from the Vredefort Dome at multiple scales: Crystallographic modeling, external and internal imaging, and EBSD structural analysis

Researchers have identified seven distinct planar fracture orientations in shocked zircon from the Vredefort Dome, providing new insights into the microstructural changes induced by high-pressure impacts. These fractures—(010), (100), (112), (1̄12), (1̄1̄2), and (011)—were documented across multiple scales using crystallographic modeling, 360° prism backscattered electron imaging, and sub-micrometer-scale EBSD analysis. Notably, some {112} fractures contain impact microtwins, the first reported in zircon, suggesting complex deformation mechanisms under extreme conditions (20–40 GPa). The study also clarifies the chronology of fracture formation, from early c-axis parallel fractures to later compressional (011) features and non-discrete crystal plastic deformation. By correlating grain-scale and sub-micrometer observations, this work refines our understanding of shock-induced microstructures in zircon, challenging prior nomenclature and advancing impact geology.

Erickson, T. M., Cavosie, A. J., Moser, D. E., Barker, I. R., & Radovan, H. A. (2012). Correlating planar microstructures in shocked zircon from the Vredefort Dome at multiple scales: Crystallographic modeling, external and internal imaging, and EBSD structural analysis. American Mineralogist, 98(1), 53–65. https://doi.org/10.2138/am.2013.4165