On the geometric relationship between deformation microstructures in zircon and the kinematic framework of the shear zone

These relationships are independent of zircon's grain size and shape, and reflect the strong geometric control of the macroscopic kinematic rotation axis on the crystal-plastic deformation behavior of zircon and on the geometry of its slip systems. We describe previously unknown rheological and crystallographic properties of zircon, which suggest a tool for deriving an orientation of the plastically deformed zircon crystals with respect to the associated foliation and stretching lineation. Additionally, relationships between zircon deformation microstructures and the macroscopic kinematic framework have implications for zircon geochronology. If deformation events result in zircon distortion and, as a consequence, partial or complete resetting of the zircon isotopic system, the age of deformation can be accurately dated.