Radiation damage allows identification of truly inherited zircon

Many studies have reported U-Pb dates of zircon that are older than the igneous rocks that contain them, and they are therefore thought to be inherited from older rock complexes. This study combines single zircon U-Pb dates and structural radiation damage (determined by Raman spectroscopy) from Pliocene and Cenozoic igneous rocks to differentiate between contamination and truly inherited zircon. Precambrian zircon in a Pliocene mid-ocean ridge gabbro showed significantly more radiation damage than expected for truly inherited grains, indicating contamination. Conversely, older grains in Cenozoic samples exhibited radiation damage consistent with young magmatic zircon, suggesting genuine inheritance. This approach provides a new method for identifying inherited zircon and revisiting previous findings.

Anders Bjerga, Håvard Hallås Stubseid, Leif-Erik Rydland Pedersen, Rolf Birger Pedersen