Combined zircon U/Pb-(U-Th)/He-Raman dating

Double- and multi-dating approaches that combine different geo- and thermochronometric dating methods on individual grains are promising tools for tackling complex geological questions: they allow us to track the history of single mineral grains from their crystallization to their present-day temperature. This is especially useful for applications to sedimentary rocks, where every grain potentially represents a different source and post-depositional heating may partially or fully erase the signal of pre-depositional cooling histories. A popular approach for detrital applications is laser-ablation-based in-situ zircon U/Pb-(U-Th)/He double-dating that determines the crystallization age (U/Pb) of each zircon grain and its cooling through the 190–170 °C ((U-Th)/He) temperature window. In this paper, we present a new multi-dating strategy that expands this scheme by adding the zircon Raman thermochronometer. This extends the temperature-sensitivity window to the 370–330 °C and 310–260 °C ranges and allows extracting more information from detrital samples, e.g., when the (U-Th)/He system has been reset by post-depositional heating. We lay out the analytical and data-evaluation procedures for our new multi-dating scheme. For proof of concept, we apply it to two sandstones from the northern Canadian Cordillera with different post-depositional thermal histories. For both samples, the results from the different dating methods are overall consistent: the age distributions of the samples and the dating results on the individual grains follow the age sequence expected from the methods’ diffusion/annealing kinetics. Minor inconsistencies likely stem from two sources: kinetic crossover between the zircon Raman and (U-Th)/He thermochronometers and difficulties matching the volumes analyzed by the different methods. In conclusion, U/Pb-(U-Th)/He-Raman multi-dating offers the prospect of enhancing established double-dating approaches, e.g., for extracting detailed thermal histories from individual zircon grains and distinguishing sediment source regions by their thermal histories. • New multi-dating scheme combining zircon U/Pb, (U-Th)/He and Raman dating. • Extraction of formation and cooling ages from large number of individual grains. • Consistent results from two sandstones from Northern Canada. • Potential relationship between discordance and disturbance of thermochronometers.