Abstract
Impact cratering ages tie the cratering process to mass extinctions, environmental changes, and potential habitability of the early Earth. However, less than a quarter of terrestrial impact craters are accurately and precisely dated, but are a ubiquitous process on Earth and other terrestrial planets. In order to test the reliability of the zircon (U-Th)/He thermochronometer in precisely dating the impact as well as post-impact hydrothermal processes, we characterized the complex intragrain microstructures and correlate the shock features to the helium diffusion kinetics. We find that deformed grains produce younger ages, complicated diffusion kinetics, and record hydrothermal system processes.