Mar 6, 2014 - Zircon (U-Th)/He dating has become a widely used thermochronologic method in the geosciences. Practitioner
Departmental Seminar Helium Diffusion in Zircon, or: How I Learned to Stop Worrying and Love the Complexity of the Zircon (U-Th)/He Thermochronometer William Guenther University of Illinois, Urbana-Champaign Zircon (U-Th)/He dating has become a widely used thermochronologic method in the geosciences. Practitioners have traditionally interpreted (U-Th)/He dates from zircons across a broad spectrum of chemical compositions with a single set of 4He diffusion kinetics derived from only a handful of crystals. However, it has become increasingly clear that a “one-size-fits-all” approach to these kinetics is inadequate, leading to erroneous conclusions and incongruent data. In this talk, I’ll focus on the radiation damage effect on He diffusion in zircon, and explain how this grain-specific effect manifests in zircon He dates. I’ll demonstrate a new damage-diffusivity model that exploits such manifestations to better constrain sample thermal histories. Finally, I’ll briefly discuss the possible importance of another grain-specific control on He diffusion in zircon, U and Th zonation.
Thursday, March 6, 2014 3:30 p.m. Room 1252, HAMP Bldg.
